Re: [Simulavr-devel] UART Interrupt and Timer problem

[Klaus Rudolph]

Hi Jakob,

great that we have found such a good tester!

> Similar problem,
I don´t believe :-)

> different interrupt. UART_DATA_READY is according to
> the data-sheet meant to stay on until switched off.
Yes! Thats seems to be your problem :-)

> However in my
> sample code (attached below) it seems that the interrupt code body
> doesn't even get called when an interrupt is raised,
the irq vector is called! Look at your timestamp: 16058 
you are running in code with symbol __vector_31 which is your INTERRUPT
routine. That is correct.


> as a few cycles
> later another one is raised again. (and so on).
That seems to be OK. The first thing you do is to enable the interrupt
again -> SEI instruction, the UDR is still set and also UDRIE is set.
This three points mean-> start a interrupt. And this is done.

I think you should not write

INTERRUPT(SIG_UART1_DATA)
please use
SIGNAL(SIG_UART1_DATA)
instead. This will not activate the interrupts before ending your 
interrupt handler.


> Also the program
> generates a "Not allowed to write to Pin! Read-Only!" error. Don't
> know where that comes from. Here is the trace:
> 

Thats really simple :-) You are running a interrupt routine and the
actual PC is saved on stack. After entering the ISR (Interrupt Service
Routine) you enable the next interrupt but not leave the ISR. You 
pushing a lot of PCs to stack and the lower RAM address space is
the io register bank. And one of the registers you are writing
is one of the pin registers. This will throw the message.
After that you are also crashing the registers and so on. 

Seems that there is only a bug in the test :-). If the behaviour is
not like the real hardware please send again a mail. But I think
your testcode is wrong.

But writing to an reserved register has crashed my simulator!
Thanks for this, I found a very stupied bug which to fix needs updating
nearly all files. I will do this the next days and put it together 
with the last changes to CVS. Thanks for that hint!

Thanks
    Klaus




>     15996 ../avrtest/avrtest.elf 0x012a: __vector_31+0x2              
>  IRQ DETECTED: VectorAddr: 62../avrtest/avrtest.elf IrqSystem:
> IrqHandlerStarted Vec: 31
> IRAM[0x10fc,,__bss_end,_end+0xfe8]=0x95 SP=0x10fb
> IRAM[0x10fb,,__bss_end,_end+0xfe7]=0x00 SP=0x10fa
>     16058 ../avrtest/avrtest.elf 0x007c: __SREG__,__SP_H__+0x1f       
>  CPU-waitstate
>     16120 ../avrtest/avrtest.elf 0x007c: __SREG__,__SP_H__+0x1f       
>  CPU-waitstate
>     16182 ../avrtest/avrtest.elf 0x007c: __SREG__,__SP_H__+0x1f       
>  CPU-waitstate
>     16244 ../avrtest/avrtest.elf 0x007c: __SREG__,__SP_H__+0x1f       
>  JMP 128f0 __stack+0x8bf9
>     16306 ../avrtest/avrtest.elf 0x0126: __vector_31                  
>  CPU-waitstate
>     16368 ../avrtest/avrtest.elf 0x0126: __vector_31                  
>  CPU-waitstate
>     16430 ../avrtest/avrtest.elf 0x0126: __vector_31                  
>  SEI SREG=[I-------]
>     16492 ../avrtest/avrtest.elf 0x0128: __vector_31+0x1              
>  PUSH R1 IRAM[0x10fa,,__bss_end,_end+0xfe6]=0x00 SP=0x10f9
>     16554 ../avrtest/avrtest.elf 0x012a: __vector_31+0x2              
>  CPU-waitstate
>     16616 ../avrtest/avrtest.elf 0x012a: __vector_31+0x2              
>  IRQ DETECTED: VectorAddr: 62../avrtest/avrtest.elf IrqSystem:
> IrqHandlerStarted Vec: 31
> IRAM[0x10f9,,__bss_end,_end+0xfe5]=0x95 SP=0x10f8
> IRAM[0x10f8,,__bss_end,_end+0xfe4]=0x00 SP=0x10f7
> [...]
> 
> and the code that produced it:
> 
> //----- Include Files
> ---------------------------------------------------------
> #include <avr/io.h>
> #include <avr/signal.h>
> #include <avr/interrupt.h>
> 
> #define F_CPU 16000000
> #define UART1_BAUD  19200
> 
> typedef unsigned char  u08;
> 
> //----- Begin Code
> ------------------------------------------------------------
> 
> void io_init(void);
> void uart1_send(char *s, int size);
> 
> int main(void)
> {
>       io_init();
> 
>       while(1) {
> 
>               char *s = "this is a test";
>               uart1_send( s, 3 );
> 
>               // delay
>               int m = 20000;
>               while( m-- );
>       }
> 
>       return 0;
> }
> 
> void io_init() {
>       // set LED pins for output
>     DDRA = _BV(DDA2) | _BV(DDA4);     
> 
>       // set BAUD rate for UART1
>       UBRR1L = ((F_CPU+(UART1_BAUD * 8L))/(UART1_BAUD * 16L)-1);
>       UBRR1H = 0;
> 
>       // init UART1
>       UCSR1B = _BV(TXEN); 
> 
>       // enable all interupts
>       sei();
> }
> 
> char *tx_buf;
> u08 tx_index;
> u08 tx_size;
> 
> void uart1_send(char *s, int size) {
>       tx_size = size;
>       tx_buf=s;
>       tx_index=0;
> 
>       // enable UART data ready interrupt
>       UCSR1B |= _BV(UDRIE); 
> }
> 
> INTERRUPT(SIG_UART1_DATA)      
> {
>       // disable data ready interrupt
>       UCSR1B ^= _BV(UDRIE);
>        
>       // check for more data
>       if( tx_index < tx_size ) {
>               // enable data ready interrupt
>               UDR1 = tx_buf[tx_index++];      
>               UCSR1B |= _BV(UDRIE); 
>       } 
> }
> 

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