ColdFire/68K Microcontrollers and ProcessorsのトピックRe: understanding CF5234's UART TX Interrupt

understanding CF5234's UART TX Interrupt

sirlenzelot — Mon, 19 Mar 2007 16:04:02 GMT

Hello,

UART TRX works fine at the moment using polling, but I'd like to use interrupts.

RX interrupt is no problem but I am not sure what I have to do for TX. Maybe someone can give a hint?

status quo:

1) set interrupt vector

2) init UART

3) fill UART_TX_q

4) activate TX interrupt (UART.UISR.TXRDY = 1)

Now my ISR is called and the TX_q will be send.

When finished, I switch off TX interrupt (UART.UISR.TXRDY = 0)

I'd like to do an internal loopback test to ensure everything is okay before granting access to UART.

For testing, I activate TX interrupt. My ISR is called and in the ISR, one Byte is put to UART.UTB and TX interrupt is switched off. Due to loopback, UART.USR.RXRDY is set and the interrupt should be triggered again, but nothing happens. UART.USR.RXRDY is set but the ISR is not called. It seems, my programm does not recognize the RX interrupt.

Code:

char BUTX = 64;

char BURX = 255;

interrupt void UART0_isr(void){// RX if ((UART0.USR.R & 0x1) == 0x1) {  BURX = UART0.UTRB.B.BUF; } else// TX if ((UART0.UISR.R & 0x1) == 0x1) {  UART0.UTRB.B.BUF = BUTX;  UART0.UISR.B.TXRDY = 0; }}

void main()

 setISR();  // set interrupt and isr

 initUART();  // set local loopback mode

 UART.UISR.TXRDY = 1; // enable UART TX interrupt

// Now ISR is called

while (BUTX != BURX) // Wait for RX interrupt

 // Do nothing

please note that i have replaced the q with a single char (BUTX / BURX) for testing.

Thanks for your suggestions.

best regards (vy 73)

Sir Lenzelot

Re: understanding CF5234's UART TX Interrupt

Arev — Mon, 19 Mar 2007 16:50:37 GMT

Hello,

First, check that UART Interruptions are enabled in your UART Initialisation Code:

MCF_UART_UIMR0 = ( 0 | MCF_UART_UISR_TXRDY // Enable Interruption TxRDY
| MCF_UART_UISR_RXRDY_FU ); // EnableInterruption RxRDY

Second, to transmit chars, Enable the UART TX, this will automatically set USR0[TxEMP,TxRDY] and cause an interrupt.

MCF_UART_UCR0 = MCF_UART_UCR_TX_ENABLED;

I Hope this helps..

Bye

Re: understanding CF5234's UART TX Interrupt

sirlenzelot — Tue, 20 Mar 2007 14:42:06 GMT

Hello Arev,

thanks for your fast answer.

For enabling the transmission of data i did not switch UART TX. I switched the interrupt on and off using UART.UIMR.TXRDY. Maybe that was the mistake.

Thanks again.

best regards (vy73)

Sir Lenzelot