Serial port API

API Overview

The calling sequence is open>set_baudrate>read/write>fulsh_io>close

open

int esp_open(char* pDeviceName)

Open the serial port by the specified device name. This operation should be used before other operations.

Parameters
pDeviceName	char*: Device name

pDeviceName

if using the fiscal module, the device name is SERIAL_EXT. Others are as follows:

• W1/W1V2
  • SLAVE MODE: DB9
  • HOST_MODE: GS0_Q1
• Q1
  • SLAVE MODE: WIZARHANDQ1
  • HOST_MODE: Q1_USB_SERIAL or USB_SERIAL
• Q1V2
  • SLAVE MODE: USB_SLAVE_SERIAL
  • HOST_MODE: USB_HOST_SERIAL or USB_SERIAL
• Q2/K2/M2
  • SLAVE MODE: USB_SLAVE_SERIAL
  • HOST_MODE: USB_HOST_SERIAL or USB_SERIAL

Returns
int	The result code, >= 0, handle of this device; <0 error code.

close

int esp_close(int nHandle)

Close the serial port opened before. The open and close apis are pair operations. If you don’t want to use this device, you should call the close api to release this device.

Parameters
nHandle	int: Handle of this device, returned from open

Returns
int	The result code, >= 0, success; <0 error code.

set_baudrate

int esp_set_baudrate(int nHandle, unsigned int nBaudrate)

Set the baud rate of the serial port so that this device can read and write in the same baud rate. This api should be used before read and write.

Parameters
nHandle	int: Handle of this device, returned from open
nBaudrate	int: Baud rate

Returns
int	The result code, >= 0, success; <0 error code.

read

int esp_read(int nHandle, unsigned char* pDataBuffer, int nExpectedDataLength, int nTimeout_MS)

Get information from the serial port.

Parameters
nHandle	int: Handle of this device, returned from open
pDataBuffer	unsigned char*: Data buffer
nExpectedDataLength	int: Data length to read
nTimeout_MS	int: Time in milliseconds. 0 : read and return immediately; <0: read until got data.

Returns
int	The result code, >= 0, success, the data length of read; <0 error code.

write

int esp_write(int nHandle, unsigned char* pDataBuffer, int nDataLength)

Send information from the serial port.

Parameters
nHandle	int: Handle of this device, returned from open
pDataBuffer	unsigned char*: Data buffer
nDataLength	int: Data length

Returns
int	The result code, >= 0, data length of written; <0 error code.

flush_io

int esp_flush_io(int nHandle)

Flush the IO buffer of the serial port.

Parameters
nHandle	int: Handle of this device, returned from open

Returns
int	The result code, >= 0, written data length; <0 error code.