JP6456649B2 - Electronic device apparatus and serial communication speed adjustment method - Google Patents

Description

  The present invention relates to an electronic apparatus device and a serial communication speed adjustment method.

Conventionally, in ATM (Automated Teller Machine), room entry management system, inventory management system, etc., there are card readers used for insertion and ejection of card-like media, data reading and writing, and the like.
For example, Patent Document 1 describes an example of a card reader for such a card-like medium.

  Here, in order for a card reader as described in Patent Document 1 to perform serial communication with a host device, it is necessary to perform communication at the same baud rate between the host device and the card reader. Generally, the card reader side is configured to compensate for the accuracy of the baud rate on the card reader side by using a highly accurate clock signal using an externally connected crystal resonator and circuit.

JP 2014-89574 A

  However, when an externally connected crystal resonator is not used and serial communication is performed with a host device using a clock incorporated in a control unit such as a CPU, communication may not be performed successfully. This is because the clock signal built in the control unit is largely fluctuated due to a temperature change or the like.

  The present invention has been made in view of such a situation, and an electronic apparatus device capable of reliably performing serial communication with a host device without using a highly accurate clock signal using a crystal resonator or the like. It is another object of the present invention to provide a serial communication speed adjustment method.

The electronic device of the present invention is connected to a host device so as to be capable of serial communication, receives a command from the host device through the serial communication, and executes processing corresponding to the command, A clock generation unit that generates a clock signal necessary for timing of storing data received by serial communication, and an inversion interval corresponding to a specific code included in the command is measured by the clock signal generated by the clock generation unit An inversion interval measuring unit that adjusts the communication speed with the host device so as to correspond to the inversion interval measured by the inversion interval measuring unit, and the communication speed is adjusted by the interval between the inversion bits. after, to anda command analyzing unit for further correcting the transmission rate by analyzing the command .
With this configuration, it is possible to reliably perform serial communication with a host device without using a highly accurate clock signal using a crystal resonator or the like.

The electronic device of the present invention includes a buffer that stores data received by the serial communication by DMA (Direct Memory Access), and the inversion interval measurement unit is configured to identify the specific data from a bit string of the data stored in the buffer. The inversion interval corresponding to the code is measured, and the command analysis execution unit calculates the count value of the clock signal corresponding to the modulation period for one bit of the serial communication from the DMA data corresponding to the entire command data. And the calculated value is used as a correction value when the next command is received .
With this configuration, data can be transferred at high speed without applying a load, received data can be reliably acquired, and the serial communication speed can be adjusted with high accuracy.

In the electronic device according to the present invention, the specific code is set so that a length of a first inverted bit string including a start bit and a length of a second inverted bit string after that is a specific ratio, and the inversion interval measurement The unit specifies the first inverted bit string and the second inverted bit string as the inverted bit string having the specific ratio, and the clock of the specified first inverted bit string and the second inverted bit string is specified. The inversion interval is measured by calculating a count value of the signal.
With this configuration, the specific code can be easily detected from the serial communication reception data.

The electronic device of the present invention is a card reader that receives the command from the host device and executes a specific process corresponding to the command on a card-like medium to be read or written. .
With this configuration, specific processing can be performed safely.

The electronic device apparatus according to the present invention is characterized in that the inversion interval measuring unit measures the inversion interval every time the command is received from the host device.
With this configuration, even if time has elapsed since the previous command was received and the clock or the like has fluctuated, it is possible to reliably adjust the speed and receive the command.

The serial communication speed adjustment method of the present invention is connected to a host device so that serial communication is possible, and is executed by an electronic device that receives a command from the host device through the serial communication and executes processing corresponding to the command. A serial communication speed adjustment method, wherein an inversion interval corresponding to a specific code included in the command is measured with a clock signal generated by a built-in clock generation unit, and corresponds to the measured inversion interval. The communication speed with the host device is adjusted, the communication speed is adjusted according to the interval of the inverted bits, and then the command is analyzed to further correct the communication speed .
With this configuration, it is possible to reliably perform serial communication with a host device without using a highly accurate clock signal using a crystal resonator or the like.

  According to the present invention, an inversion interval corresponding to a specific code included in a serial communication command is measured with a built-in clock signal, so that a high-order clock signal using a crystal resonator or the like is not used. It is possible to provide an electronic device device and a serial communication speed adjustment method that can reliably perform serial communication with the device.

It is a system configuration figure of the card control system concerning an embodiment of the invention. It is a flowchart of the command reception execution process which the card reader shown in FIG. 1 performs. FIG. 3 is a conceptual diagram of inversion interval measurement processing shown in FIG. 2. FIG. 3 is a conceptual diagram of inversion interval measurement processing shown in FIG. 2.

<Embodiment>
[Configuration of Card Control System X]
With reference to FIG. 1, the structure of the card | curd control system X which concerns on embodiment of this invention is demonstrated. The card control system X of the present embodiment is a system that uses a card-like medium 3 such as an ATM, an entry management system, an inventory management system, an entry / exit management system (hereinafter referred to as “ATM etc.”).
The card control system X of the present embodiment includes a card reader 1, a host device 2, and a card-like medium 3.

  The card reader 1 is a card reader device built in an ATM or the like. The card reader 1 is connected to the host device 2 so that transmission / reception can be performed by serial communication using, for example, a start-stop synchronization method and a half-duplex communication method. Thus, when the card-like medium 3 is inserted into the card reader 1, the card reader 1 receives a command from the host device 2 by serial communication, and performs a specific process corresponding to the command on the card-like medium 3. Execute.

  The host device 2 is a main body such as ATM. The host device 2 controls the power supply of the card reader 1. Further, the host device 2 transmits various commands to the card reader 1 by serial communication, and receives the execution results of these commands.

  The card-like medium 3 is a non-temporary recording medium such as a magnetic card, IC card, or RFID (Radio Frequency Identification) card. The card-like medium 3 is recorded with value information indicating a monetary value such as a credit card, prepaid card, or cash card, and unique information such as an ID (Identification) code.

  The card reader 1 includes a control unit 10, a main storage unit 20, an auxiliary storage unit 30, and a card reading / writing unit 40.

The control unit 10 is a control calculation means such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit).
As will be described later, the control unit 10 has a built-in clock generation circuit and can perform serial communication with the host device 2 using the generated clock.

The main storage unit 20 is a recording medium such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), or MRAM (Magnetoresistive Random Access Memory).
As will be described later, various buffers are secured in the main storage unit 20, and data is stored in the buffers.

The auxiliary storage unit 30 is a non-volatile recording medium such as a ROM (Read Only Memory) or a flash memory.
The auxiliary storage unit 30 stores a control program such as firmware of the card reader 1 and various data.

  The card reading / writing unit 40 includes a magnetic head, an electromagnetic induction coil, an IC connection interface, an RFID antenna, a driving mechanism, a sensor, a state for inserting and ejecting the card-like medium 3, and a state for reading or writing the card-like medium 3 A display unit such as an LED (Light Emitting Diode) or a liquid crystal for display is provided. Further, the card reading / writing unit 40 may include an input unit such as a dip switch, a jumper pin, or a switch for performing initial setting of the card reader 1 and various instructions.

  Note that the control unit 10, the main storage unit 20, and the auxiliary storage unit 30 may be an integrally configured microcomputer (micro controller) or the like.

More specifically, the control unit 10 includes a clock generation unit 100, an inversion interval measurement unit 110, a communication speed adjustment unit 120, a DMA unit 130 (Direct Memory Access), and a command analysis execution unit 140. Contains.
In the main storage unit 20, areas for the DMA buffer 200 (Buffer) and the command data buffer 210 are secured.
In addition, the auxiliary storage unit 30 stores baud rate setting data 310.

  The clock generation unit 100 generates a clock signal necessary for timing of storing received data. Since the clock generation unit 100 includes an oscillation circuit such as an on-chip oscillator, it is not necessary to connect an external crystal oscillator or the like. Further, the clock signal generated from the clock generation unit 100 is divided at a specific ratio in accordance with the timing required for each unit. Further, the speed of the clock signal generated by the clock generation unit 100 may vary within a specific range from a predetermined speed depending on the temperature of the control unit 10, the supplied voltage, and the like. The clock generation unit 100 can also supply clock signals necessary for various controls of the control unit 10. It is also possible to set a software timer or the like for measuring various timings based on the clock signal generated by the clock generation unit 100.

The inversion interval measurement unit 110 measures the inversion bit interval (hereinafter referred to as “inversion interval”) corresponding to the specific code included in the command, using the clock signal generated by the clock generation unit 100. Here, in the present embodiment, for the serial communication received signal, the “1” bit that is H (High) level is set to “non-inverted bit” and the “0” bit that is L (Low) level is set. This is called “inverted bit”. In the following description, the inversion interval is a count value of a clock signal generated by the clock generation unit 100 corresponding to a modulation period corresponding to one bit of serial communication received data from the host device 2.
Specifically, the inversion interval measurement unit 110 searches the bit string of the inversion bit corresponding to the specific code from the bit string of the DMA data 500 of the DMA buffer 200 stored in the main storage unit 20. The inversion interval measuring unit 110 calculates the bit string length of the inversion bits, that is, the count value of the clock signal, and uses this to determine the inversion interval.

  More specifically, the inversion interval measurement unit 110 specifies the first inversion bit string and the second inversion bit string corresponding to the specific code, and clocks the specified first inversion bit string and the second inversion bit string. The count value of the signal is calculated and the inversion interval is measured. Here, in the present embodiment, the specific code is a code for starting text in the command. The code for starting text includes a bit string having a specific ratio between the length of the first inverted bit string including the start bit and the length of the second inverted bit string thereafter. For this reason, the inversion interval measurement unit 110 searches the DMA data 500 stored in the DMA buffer 200 for a bit string in which the length of successive inversion bits has this specific ratio as a specific code, The count values of the clock signals of the first inverted bit string and the second inverted bit string of the code are calculated, and the inversion interval is measured. In the present embodiment, the inversion interval measurement unit 110 calculates the inversion interval in units of one clock signal that is one bit of the specific code.

  The inversion interval measurement unit 110 measures the inversion interval every time a command is received from the host device 2. The inversion interval measuring unit 110 measures the inversion interval every time, for example, when receiving a command immediately after power is supplied to the card reader 1 by the host device 2 or when receiving a command when returning from the standby state. .

The communication speed adjustment unit 120 is connected to the card reader 1 based on the inversion interval measured by the inversion interval measurement unit 110 in order to match the communication speed from the card reader 1 to the upper device 2 with the communication speed of the upper device 2. The communication baud rate (communication speed) to the host device 2 is adjusted.
More specifically, the communication speed adjustment unit 120 stores the inversion interval calculated by the inversion interval measurement unit 110 in the baud rate setting data 310 of the auxiliary storage unit 30 as a value corresponding to the baud rate. The count value of the clock signal corresponding to the stored baud rate is a value obtained by adjusting the communication speed corresponding to the inversion interval.

The DMA unit 130 is a built-in DMA controller that performs DMA control. The DMA unit 130 receives the periodic data of the serial signal reception line (RxD) using the DMA function in response to the transfer start signal from the higher-level device 2, and directly receives the received data as DMA data 500 as a dedicated DMA. Save to buffer 200.
The control unit 10 may be configured not to include the DMA unit 130, as will be described later. Further, a configuration in which a DMA controller is provided separately from the control unit 10 may be employed.

The command analysis execution unit 140 analyzes the command and executes specific processing corresponding to the analyzed command. The command analysis execution unit 140 analyzes a command from the DMA data 500 in the DMA buffer 200 at the speed adjusted by the communication speed adjustment unit 120. This command is used for specific processing such as initialization of the card reader 1, acquisition and display of status (status information), insertion and ejection of the card-like medium 3, reading and writing of data on the card-like medium 3, and updating of firmware. Data that includes instructions. Further, the command data 510 may include a firmware program or data of the card reader 1.
The command analysis execution unit 140 transmits the execution result of the command to the higher-level device 2 through the serial signal transmission line (TxD).

The DMA buffer 200 is a dedicated buffer in which the DMA data 500 received by the DMA unit 130 is stored. The DMA data 500 is a bit string sampled at a sampling rate based on the clock signal generated by the clock generation unit 100. The sampling speed of the DMA data 500 is a speed necessary for adjusting the baud rate of serial communication, and is, for example, a speed that is several times the specified baud rate of serial communication that can communicate with the host device 2.
The DMA data 500 may be a bit string acquired at a specific cycle by a real-time timer created by a clock signal.

The command data buffer 210 is a buffer for storing command data 510 analyzed from the DMA data 500.
The command data 510 is read from the DMA data 500 stored in the DMA buffer 200 by the command analysis execution unit 140 using the clock signal count value corresponding to the baud rate set in the baud rate setting data 310 as a sampling interval. This is the data that was issued.

  The baud rate setting data 310 is data related to the baud rate of serial communication. The baud rate setting data 310 includes the count value of the clock signal calculated corresponding to the baud rate of the higher-level device 2. The count value of the clock signal is a value corresponding to a baud rate defined by serial communication such as RS-232C, a value obtained by adjusting a communication speed corresponding to an inversion interval, a correction value when the next command is received, or the like.

  Further, the baud rate setting data 310 includes a default value of the baud rate when receiving the first command (hereinafter referred to as “first command”) transmitted from the host apparatus 2 immediately after the power is turned on. For example, the default value of the baud rate is set by firmware, or is set by reading a dip switch or jumper pin combination of the input unit. As the default value of the baud rate, a specific value defined by RS-232C, such as 9,600 bps to 115.2 Kbps, is set as an initial value at the time of factory shipment.

  The inversion interval measurement unit 110, the communication speed adjustment unit 120, and the command analysis execution unit 140 develop a stored control program (not shown) in the main storage unit 20 for the auxiliary storage unit 30, and The functions of each unit can be realized by executing the process 10. The other units are realized as circuit hardware.

[Command reception execution processing by the card reader 1]
Next, a command execution process according to the embodiment of the present invention will be described with reference to FIGS.
In the command reception execution process of this embodiment, command reception from the host device 2 is started, the serial communication speed is adjusted, the baud rate is corrected, and the command execution result is returned. Here, as described above, the host device 2 and the card reader 1 are connected by serial transmission / reception. The card reader 1 measures the inversion interval from the received data transmitted from the host device 2 and sets the baud rate when the card reader 1 itself transmits data to the host device 2 to be the same as that of the host device 2. . This correction is executed every time a serial communication command is received from the host device 2. Thereafter, the card reader 1 starts specific processing corresponding to the received command, performs final correction of the communication speed, and responds to the host device 2 with the execution result of the command.

In the command reception execution processing of this embodiment, the control unit 10 mainly executes a control program (not shown) stored in a storage medium using hardware resources in cooperation with each unit. As a result, the serial communication speed adjustment method and the serial communication speed adjustment program of this embodiment can be realized.
The details of the command reception execution process of this embodiment will be described step by step with reference to the flowchart of FIG.

(Step S101)
First, the DMA unit 130 performs serial communication start processing.
When data is transmitted from the host device 2 by serial communication, the DMA unit 130 stores the inversion interval of the RxD signal as DMA data 500 in the DMA buffer 200 using the DMA function.

(Step S102)
Next, the command analysis execution unit 140 determines whether or not the analyzed command data 510 is consistent.

  First, the command analysis execution unit 140 converts the DMA data 500 in the DMA buffer 200 into a command and stores it in the command data buffer 210. At this time, the command analysis execution unit 140 reads the baud rate setting data 310 from the auxiliary storage unit 30. The command analysis execution unit 140 reads the DMA data 500 using the count value of the clock signal set in the baud rate setting data 310 as a sampling interval, and converts it into command data 510. At this time, as a count value of the clock signal, a value corresponding to a specific default value is calculated and used when the first command is received immediately after the power is turned on. Further, after the second time, the command analysis execution unit 140 uses the value set in the baud rate setting data 310 in step S110 described later as the count value. That is, after the second time, the command analysis execution unit 140 uses the value corrected when the immediately previous command is received, “correction value when receiving the next command”, which will be described later, as the count value.

Then, the command analysis execution unit 140 checks the data consistency of the command data 510 stored in the command data buffer 210 by a parity check, a message break check, a CRC (Cyclic Redundancy Check), or the like.
The command analysis execution unit 140 determines Yes when the command data 510 is consistent. The command analysis execution unit 140 determines No in other cases.
In the case of Yes, the command analysis execution unit 140 proceeds with the process to step S108.
In No, the command analysis execution part 140 advances a process to step S103.

(Step S103)
If the command data 510 is not consistent, the command analysis execution unit 140 determines whether the command is the first command. The command analysis execution unit 140 determines Yes when the analyzed command data 510 is the first command. In other cases, that is, in the case of the second and subsequent commands, the command analysis execution unit 140 determines No.
In the case of Yes, the command analysis execution unit 140 proceeds with the process to step S104.
In No, command analysis execution part 140 advances a process to Step S107.

(Step S104)
If it is the first command, the inversion interval measurement unit 110 performs inversion interval measurement processing.
The inversion interval measurement unit 110 measures the inversion interval in which a specific code is manipulated from the DMA data 500 stored in the DMA buffer 200.

  FIG. 3A shows an example in which a bit string “0xF2” that is a code of “STX” that is a text start code of a command is used as the specific code. Serial communication data is transmitted in units of a total of 10 bits, with 1 start bit, 8 data bits, 1 stop bit, and 1 parity bit as units. At this time, the start bit is always “0” and the stop bit is always “1”. Data bits B0 to B7 are sequentially transmitted from the least significant bit (LSB) to the most significant bit (MSB).

  For this reason, when the specific code is “0xF2”, the first inverted bit string “00”, the non-inverted bit string “1”, the subsequent second inverted bit string “00”, and the subsequent non-inverted bit string “1111” ", Stop bit" 1 ", and finally a parity bit. Therefore, in this example, the length T0 of the first inverted bit string is equal to the length T2 of the second inverted bit string thereafter, that is, a specific ratio of 1: 1.

  FIG. 3B shows an example of T0: T2 = 1: 1 data in the DMA data 500 stored in the DMA buffer 200. As described above, the inversion interval measurement unit 110 searches for a bit string at a location where T0: T1 = 1: 1, and specifies the first inversion bit string and the second inversion bit string. The inversion interval measurement unit 110 calculates an inversion interval, which is a count value of the clock signal corresponding to one bit of the specific code, from the specified first inversion bit sequence and second inversion bit sequence. In the case of the example of FIG. 3B, the inversion interval measurement unit 110 calculates as inversion interval = (length of T0 + length of T2) / 4. In this example, since the length of T0 = 6 and the length of T2 = 6, the inversion interval = 3 (period) is calculated.

  The inversion interval measurement unit 110 may also use the length of T1 when calculating the inversion interval. In this case, the inversion interval measurement unit 110 can calculate the inversion interval = (T0 length × 2 + T1 length + T2 length × 2) / 5. In addition, the DMA data 500 stored in the DMA buffer 200 may actually be sampled fine enough to reduce the error.

(Step S105)
Next, the communication speed adjustment unit 120 performs communication speed adjustment processing.
The communication speed adjustment unit 120 adjusts the communication speed with the host device 2 so as to correspond to the inversion interval measured by the inversion interval measurement unit 110. Specifically, the communication speed adjustment unit 120 stores the measured inversion interval in the baud rate setting data 310 of the auxiliary storage unit 30. Thereby, it becomes possible to adjust the communication speed with the high-order apparatus 2. FIG.
In the example of FIG. 3B described above, the communication speed adjustment unit 120 sets the inversion interval to 3 (cycle), and sets this in the baud rate setting data 310 as a value adjusted for the communication speed.

  With this configuration, the communication speed adjustment unit 120 does not need to set a fixed baud rate such as 9,600 bps, 38,400 bps, 115,200 bps. Even when the speed of the clock signal fluctuates due to temperature fluctuation or the like, the same baud rate as that of the host device 2 is maintained, and a state where serial communication is possible can be maintained.

(Step S106)
Next, the command analysis execution unit 140 determines whether data demodulation is possible.
The command analysis execution unit 140 attempts to demodulate the command data 510 from the DMA data 500 stored in the DMA buffer 200 at the adjusted communication speed. That is, the command analysis execution unit 140 resamples the DMA data 500 stored in the DMA buffer 200 at the interval of the count value of the clock signal set in the baud rate setting data 310 and converts it to the command data 510 again.

The command analysis execution unit 140 checks the consistency of the converted command data 510 as in step S102 described above. In the example of FIG. 3B described above, the command analysis execution unit 140 checks the consistency when the DMA data 500 is read at 3 (cycle) and converted into the command data 510. The command analysis execution unit 140 determines Yes when there is consistency. The command analysis execution unit 140 determines No when there is no consistency.
In the case of Yes, the command analysis execution unit 140 proceeds with the process to step S108.
In the case of No, the command analysis execution unit 140 returns the process to step S101 and waits for another command transmission from the host device 2 because it cannot be demodulated.

(Step S107)
In the case of the second and subsequent commands, the command analysis execution unit 140 performs NAK response processing.
If the command is not the first command from the power supply or standby state of the card reader 1 but the command from the second time onward, there is a possibility of a communication error due to equipment failure, noise contamination, unauthorized operation, or the like.
For this reason, the command analysis execution unit 140 responds “0x15”, which is the code of the negative response code “NAK”, to the higher-level device 2 by TxD of the transmission line.
Thereafter, the command analysis execution unit 140 returns the process to step S101.

(Step S108)
If the command data 510 is consistent, the command analysis execution unit 140 performs ACK response processing.
According to FIG. 4, the command analysis execution unit 140 of the card reader 1 responds to the higher order apparatus 2 with “0x06”, which is the code of the acknowledgment code “ACK”, to the higher order apparatus 2 by TxD.

(Step S109)
Next, the command analysis execution unit 140 performs command response processing.
The command analysis execution unit 140 interprets the command data 510 stored in the command data buffer 210 and starts executing a specific process corresponding to the command. For example, the command analysis execution unit 140 instructs the card reading / writing unit 40 to insert, eject, read, or write the card-like medium 3. Further, for example, the command analysis execution unit 140 executes processing such as status reading of the card reader 1 itself or firmware update.

(Step S110)
Next, the command analysis execution unit 140 performs communication speed correction processing.
The command analysis execution unit 140 corrects the communication speed based on the DMA data 500 stored in the DMA buffer 200 stored by the DMA unit 130 when the command is received. The command analysis execution unit 140 divides the count value (length) of the clock signal corresponding to all the DMA data 500 interpreted as the command data 510 by the total number of bits of the command data 510, and outputs one bit of the command data 510. The count value of the clock signal corresponding to is calculated. That is, the command analysis execution unit 140 calculates the count value of the clock signal corresponding to the modulation period for one bit of serial communication from the DMA data 500 corresponding to the entire command data 510. The command analysis execution unit 140 sets the calculated value in the baud rate setting data 310 as a correction value when the next command is received.

  With this configuration, once the communication speed is adjusted by the inversion interval, the command is analyzed and further corrected, so that the communication speed with the host device 2 can be adjusted with higher accuracy. . As a result, when the next command is transmitted from the host device 2 in the time when the control unit 10 has a small fluctuation in heat or the like, it is possible to increase the possibility of easier analysis. Therefore, the effect of reducing the waiting time until execution of a specific process for the command can be expected.

(Step S111)
Next, the command analysis execution unit 140 performs command result response processing.
According to FIG. 4, after the command execution is completed, the command analysis execution unit 140 transmits a response (response) of the command execution result to the higher-level device 2 at the baud rate corrected with the calculated average value. .

In response to this, the host device 2 responds to the card reader 1 with an ACK response.
Thereafter, the command analysis execution unit 140 returns the process to step S101 and enters a standby state until a command is transmitted from the higher-level device 2 again.
Note that when the standby state of the card reader 1 continues longer than a specific time, the host device 2 may stop supplying power to the card reader 1.
This is the end of the description of the command reception execution process according to the embodiment of the present invention.

[Main effects of this embodiment]
With the configuration described above, the following effects can be obtained.
A card reader 1 according to an embodiment of the present invention is an electronic device that is connected to a host device 2 through serial communication, receives a command from the host device through serial communication, and executes processing corresponding to the command. The clock generation unit 100 that generates a clock signal necessary for the timing of storing data received by serial communication, and the inversion interval corresponding to the specific code included in the command are represented by the clock signal generated by the clock generation unit 100. A reversing interval measuring unit 110 for measuring and a communication speed adjusting unit 120 for adjusting a communication speed with a host device so as to correspond to the reversing interval measured by the reversing interval measuring unit 110 are provided.

That is, the card reader 1 of the present embodiment calculates a value corresponding to the baud rate from the received data of the serial signal line (RxD signal) from the host device 2 by the clock signal of the control unit 10 of the card reader 1 itself.
With this configuration, even if the clock signal of the control unit 10 of the card reader 1 fluctuates due to a temperature change of the control unit 10 or the like, serial communication can be reliably performed with the host device 2. As a result, the card reader 1 and the host device 2 can avoid using a circuit including an external crystal oscillator that generates a highly accurate clock signal in terms of circuit configuration. In addition, it is possible to use an inexpensive control unit 10 in which the accuracy of the built-in clock is not higher than that of a circuit including an external crystal oscillator. Therefore, the cost reduction effect of the whole system can be expected.

  Further, the card reader 1 does not need to communicate at a prescribed baud rate, and can communicate by setting a baud rate based on the DMA data 500 from the higher-level device 2. That is, based on the DMA data 500 from the higher-level device 2, it is possible to realize a mechanism that can set the serial communication baud rate of the card reader 1. As a result, serial communication can be reliably performed even in a configuration in which the host device 2 does not use a prescribed baud rate such as the RS-232C standard or the baud rate is changed every time a command is transmitted. Can do.

  In addition, the externally connected crystal resonator has a problem of high cost. Since the card reader 1 according to the present embodiment does not use an externally connected crystal resonator, the manufacturing cost can be reduced.

  The card reader 1 is usually built in the host device 2 and processes the card-like medium 3 that handles monetary value. Therefore, the data communication between the card reader 1 and the host device 2 can be made difficult to be decoded by executing the processing with the host device 2 after adjusting the speed in the serial communication with the host device 2. . For this reason, as a result, the possibility of skimming or hacking of card information of the card-like medium 3 can be reduced, and security can be improved.

  The card reader 1 according to the embodiment of the present invention includes a buffer for storing serial communication commands by DMA (Direct Memory Access), and the inversion interval measuring unit 110 includes a DMA stored in the DMA buffer 200. The inversion interval corresponding to the specific code is measured from the bit string of the data 500.

  With this configuration, even when the host device 2 transmits at a high baud rate of 115, 200 bps or the like, data can be transferred at high speed without imposing a load on the control unit 10, and DMA data for serial communication can be reliably transmitted. 500 can be acquired. Further, there is no limitation on the clock speed at which the control unit 10 operates, and the communication speed can be adjusted. Further, since the error in sampling the DMA data 500 is reduced compared to the case where the control unit 10 directly acquires the DMA data 500, the clock signal cycle can be calculated more reliably and the speed can be adjusted with high accuracy. And correction becomes possible.

In the card reader 1 according to the embodiment of the present invention, the specific code is set so that the length of the first inverted bit string including the start bit and the length of the subsequent second inverted bit string have a specific ratio. The inversion interval measuring unit 110 identifies the first inversion bit sequence and the second inversion bit sequence as the inversion bit sequence having a specific ratio, and the identified first inversion bit sequence and second inversion bit sequence are clocks. The counter value is measured by calculating the count value of the signal.
With this configuration, the specific code can be easily detected from the serial communication DMA data 500, the inversion interval can be reliably measured, and the communication speed can be adjusted.

The card reader 1 according to the embodiment of the present invention receives a command from the host device 2 and executes a specific process corresponding to the command on the card-like medium 3 to be read or written. And
With this configuration, the card reader 1 can reliably receive a command from the higher-level device 2, and specific processing for the card-like medium 3 can be reliably performed.

The card reader 1 according to the embodiment of the present invention is characterized in that the inversion interval measurement unit 110 measures the inversion interval every time a command is received from the host device 2.
With this configuration, the speed is adjusted each time a command is received. Therefore, even if the clock of the control unit 10 fluctuates after a lapse of time from the previous command reception, the command from the higher-level device 2 can be surely received. Data 510 can be received. Usually, several minutes to several hours pass until the card-like medium 3 is inserted into the card reader 1 and a specific process is executed, and then another card-like medium 3 is inserted. For this reason, the communication speed can be adjusted more reliably by measuring the inversion interval each time.

[Other Embodiments]
In the above-described embodiment, the adjustment of the baud rate of the serial communication between the card reader 1 and the higher-level device 2 in the card control system X based on the received data between the higher-level device 2 has been described.
However, the card reader 1 generates a software timer using the clock signal of the clock generation unit 100 of the control unit 10 and uses it for purposes such as periodic sensor state monitoring and LED blinking control. For this reason, when the communication speed from the host device 2 has already been set, it is possible to correct the time of the software timer based on the adjusted baud rate setting data 310.
As a result, the time of the software timer can be corrected regardless of fluctuations in the clock signal of the control unit 10, and operations such as sensor state monitoring and LED blinking control are ensured.

Further, in the above-described embodiment, an example in which the function of the DMA unit 130 built in the control unit 10 is used to acquire the DMA data 500 from the serial signal line (RxD signal) from the host device 2 to the card reader 1. explained.
However, for example, even if the control unit 10 having a clock speed of about 25 MHz is used, if the baud rate is about 38,400 bps, the DMA data 500 is acquired by PIO (Programmed I / O) without using this DMA. It is possible enough to do. For this reason, for example, if the card reader 1 has a communication specification with an upper limit of the baud rate of 38,400 bps, the baud rate may be automatically corrected without using the DMA function.
As a result, the control unit 10 without the DMA function can be used, and the cost can be reduced.

In the above-described embodiment, the count value of the clock signal corresponding to one bit of the command data 510 is calculated and used as the inversion interval for adjusting the communication speed.
However, it is possible to set the baud rate without directly using the count value of the clock signal. For example, a prescribed baud rate and a deviation from this prescribed baud rate may be calculated from the count value of the clock signal, and this may be used for adjusting the communication speed with the host device 2.

  In this case, the communication speed adjustment unit 120 selects a value closest to the baud rate of the fixed value of RS-232C serial communication such as 9,600 bps, 38,400 bps, 115,200 bps, and the value of “deviation” from this value. Is calculated as an offset value. For example, when the predetermined bit rate (bps) of sampling of the DMA data 500 is 338 kbps and the count value of the clock signal that is the inversion interval for 1 bit is “3”, the inversion interval time is about 8.68 μs. Therefore, the baud rate is calculated as 115,200 bps. The communication speed adjustment unit 120 stores the selected baud rate and offset value in the main storage unit 20, and uses these to adjust the communication speed with the host device 2.

  With this configuration, it is possible to easily calculate a deviation from the baud rate set in the host device 2 or the card reader 1. For this reason, it becomes easy to perform the setting of the above-mentioned software timer and the timing adjustment of each other part.

In the above-described embodiment, an example in which the speed of serial communication is adjusted for the card control system X has been described.
In contrast, any electronic device that performs serial communication with the host device 2 can perform speed adjustment in the same manner as the speed adjustment method of the present embodiment. Further, the present invention can also be applied to serial communication using a specific code other than RS-232C.
With this configuration, it is possible to reduce processing time and cost related to adjustment of serial communication of various electronic devices.

In the above-described embodiment, an example in which the specific code in which the length of the first inverted bit string and the length of the second inverted bit string thereafter is 1: 1 is described. However, a specific code whose length is 1: n (arbitrary multiple) may be used as the specific code. Further, as the specific code, data that has a specific pattern may be used to detect this pattern.
With this configuration, it is possible to reliably adjust the communication time according to the characteristics of the serial communication signal.

  Note that the configuration and operation of the above-described embodiment are examples, and it is needless to say that the configuration and operation can be appropriately changed and executed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Card reader 2 Host apparatus 3 Card-like medium 10 Control part 20 Main memory part 30 Auxiliary memory part 40 Card reading / writing part 100 Clock generation part 110 Inversion interval measurement part 120 Communication speed adjustment part 130 DMA part 140 Command analysis execution part 200 DMA buffer 210 Command data buffer 310 Baud rate setting data 500 DMA data 510 Command data X Card control system

Claims (6)

It is connected to the host device so that serial communication is possible.
An electronic device device that receives a command from the host device through the serial communication and executes processing corresponding to the command,
A clock generation unit that generates a clock signal necessary for the timing of storage of data received by the serial communication;
An inversion interval measurement unit that measures an interval of inversion bits corresponding to a specific code included in the command, using the clock signal generated by the clock generation unit;
A communication speed adjusting unit that adjusts the communication speed with the host device so as to correspond to the interval between the inverted bits measured by the inversion interval measuring unit ;
An electronic device apparatus comprising: a command analysis execution unit that analyzes the command and further corrects the communication speed after adjusting the communication speed according to the interval of the inverted bits . A buffer for storing data received by the serial communication by DMA (Direct Memory Access);
The inversion interval measurement unit measures an interval between inversion bits corresponding to the specific code from a bit string of data stored in the buffer ,
The command analysis execution unit calculates a count value of the clock signal corresponding to a modulation period for one bit of the serial communication from the DMA data corresponding to the entire data of the command, and calculates the calculated value, The electronic device apparatus according to claim 1, wherein the correction value is set when the next command is received . The specific code is set so that the length of the first inverted bit string including the start bit and the length of the second inverted bit string after that is a specific ratio,
The inversion interval measurement unit specifies the first inversion bit string and the second inversion bit string as an inversion bit string having the specific ratio, and specifies the specified first inversion bit string and the second inversion bit string. The electronic device apparatus according to claim 1, wherein a count value of the clock signal of a bit string is calculated and an interval between the inverted bits is measured. 4. The card reader according to claim 1, wherein the card reader receives the command from the host device and executes a specific process corresponding to the command on a card-like medium to be read or written. The electronic device apparatus according to 1. The electronic device apparatus according to claim 4, wherein the inversion interval measurement unit measures the inversion bit interval each time the command is received from the host device. It is connected to the host device so that serial communication is possible.
A serial communication speed adjustment method executed by an electronic device that receives a command from the host device through the serial communication and executes processing corresponding to the command,
Measure the interval of the inverted bits corresponding to the specific code included in the command with the clock signal generated by the built-in clock generator,
Adjust the communication speed with the host device so as to correspond to the measured inverted bit interval ,
A serial communication speed adjustment method, wherein the communication speed is further adjusted by analyzing the command after adjusting the communication speed according to the interval of the inverted bits .

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