unexpected ustart1 isr

[denis]

Posted on September 05, 2013 at 16:06

Attached is the pic showing the ustart1 registers. I do not see why i get usart1 irq, but it is ... What am I missing? My isr is stuck because something needs to be cleared.

void serial_port::isr_x() {     if (USART_GetITStatus(m_usart, USART_IT_RXNE) != RESET)     {        uint8_t b= USART_ReceiveData(m_usart);       // . . .     }     if(USART_GetITStatus(m_usart, USART_IT_TXE) != RESET)     {         if (have data ...)           USART_SendData(m_usart, outByte);       else         // Disable the USART Transmit interrupt         disableTxInterrupt();     } }

[Tesla DeLorean]

Posted on September 05, 2013 at 16:59

Consider if the debugger is interfering with the peripheral, ie reading USART1->DR changes USART1->SR.

Don't park a debugger watch over the peripheral if you want to know what's going on inside. Add your own instrumentation, and understand the side-effects. Consider using the SWV channel. Interrupts can also be cleared explicitly USART_ClearITPendingBit(USART1, USART_IT_RXNE);    /* Clear the USART RXNE interrupt */