Serial port API

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Functions

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 Device name

Returns

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 Handle of this device, returned from open

Returns

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 Handle of this device, returned from open
nBaudrate Baud rate

Returns

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

Returns

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

write

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

Send information from the serial port.


Parameters

nHandle Handle of this device, returned from open
pDataBuffer Data buffer
nDataLength Data length

Returns

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

flush_io

 int esp_flush_io(int nHandle)

Flush the IO buffer of the serial port.


Parameters

nHandle Handle of this device, returned from open

Returns

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