esp8266 serial (UART0) tx/rx
The esp8266 SDK manual and examples are pretty poor. There an example uart.c knocking around, but the receive code is incomplete. I built this out a bit so I could read serial data from the circular buffer. You can download my update files here: uart.c,
uart.h
, uart_register.h. Only uart.c has been changed significantly. (update, I’ve put a tarball which a complete echo example here. UART data can then be received as follows:
int c = uart0_rx_one_char();
if(c != -1) {
char out[30];
os_sprintf(out,"received %c",c);
debug(out);
}
Or if you just want to echo received characters:
int c = uart0_rx_one_char();
if(c != -1) {
uart_tx_one_char(c);
}
I’ve only built out reading a single character, but it should be easy to build more general functions on top of that. You can still use the old function to transmit:
uart0_tx_buffer(data,strlen(data));
As always you need to init the UART in user_init with something like:
uart_init(BIT_RATE_9600,BIT_RATE_9600);
Or the UART will be configured with 74KBPS (which is a pretty odd value).
Update: You may also want to take a look at my notes on messaging system in the esp8266 SDK, and how it can potentially be used for this application.
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