Serial port API
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.