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UART0 Receive Overflow [RX OVF!!]

Posted: Thu Oct 12, 2017 6:03 pm
by gailu
Hi Expressif Team,

We are communicating with server through modem connected to esp8266 over UART0. When our server sends a message [256] bytes, We get UART Rx overflow and message RX OVF!! is printed on console that is coming from uart.c

We have increased following defines in uart.h as the maximum size packet that our server can send is 768 bytes.
#define UART_TX_BUFFER_SIZE 768 //Ring buffer length of tx buffer
#define UART_RX_BUFFER_SIZE 768 //Ring buffer length of rx buffer

However this does not help to stop RX OVF!!

How can we increase the Receive buffer to avoid RX OVF!! error?

esp is communicated with modem on baud rate 115200

Does UART0 support Software Flow Control (XON/XOFF)?

Your help is appreciated.

Re: UART0 Receive Overflow [RX OVF!!]

Posted: Sat Oct 14, 2017 3:47 am
by gailu
We checked uart.c and found 100 bytes threshold set with following code

WRITE_PERI_REG(UART_CONF1(uart_no),
((100 & UART_RXFIFO_FULL_THRHD) << UART_RXFIFO_FULL_THRHD_S) |

Can you please let me know what is the maximum threshold we can set?
What is the maximum size of UART0 RXFIFO?

Re: UART0 Receive Overflow [RX OVF!!]

Posted: Sat Oct 14, 2017 8:34 pm
by blubb
I have no clue, but the first thing I'd try is to raise the CPU frequency to 160 MHz. Maybe the ESP is simply to slow to handle all data in time, so the buffer fills up faster than it can be processed.
The second thing I'd try is to lower the baud rate (in the sender and receiver of course).