Posted on May 17, 2011 at 13:41[Q] How are you determining a loss of characters? The code doesn't handle 'zero' bytes.
[Q] Is the data being extracted at a single point?
[A] I receive a fixed length message from UART2 and send it to
USART1. USART2 push bytes interrupt mode, the pop to USART2 is into
while (program control). The flow is something like this (simplified):
// interrupt routine
void USART2_IRQHandler(void) {
uint8_t c;
if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET) {
c = (uint8_t)USART_ReceiveData(USART2);
QueuePush(c);
}
}
// main.c
while(1)
{
...
while(QueueCheck())
{
Data = QueuePop();
USART_SendData(USART1, Data);
while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);
}
...
}
[Q] Does a count of received characters match those transmitted?
[A] The missing data get in from interrupt routine but they get lost
somewhere after: if I put a counter variable counting the number of
times USART2_IRQHandleri is called, I see that all data getting in.
[Q] Are any characters being lost to overrun or framing errors?
[A] I get all data from USART RX, is there chances to miss due to TX
overrun? Since I wait for FLAG_TC reset I think it could not be the
problem. What about framing error? Signal integrity is very good.
[Q] Are you writing the data into flash? This stalls the processor and result in overruns.
[A] No just echoing USART2 to USART1
[Q] Are you using flow control?
[A] No
[Q] Does increasing the CPU speed, or decreasing the baud rate improve the situation?
[A] I'm checking these. As first shot it seems not.
Thanks very much.
Fil
