AVR-Chat

Hi everyone.

I am trying to get an ATMEGA8 to talk to a terminal app on my PC by
RS232. I have used the compiler [WinAVR] and programmer [PONY ISP]
to compile and run other programs so I know that these parts of the
issue are OK.

Here is the source....



Any ideas?


I have an 8Mhz oscillator

Note: if anyone has simpler source with makefile please send it to
me. Thanks



* >simcom -38400 /dev/ttyS0 */

#include <avr/io.h>
#include <avr/signal.h>
#include <avr/interrupt.h>

static void putchar(unsigned char ch){
while ((inp(UCSRA) & 0x20) == 0) {};
outp(ch, UDR);
while ((inp(UCSRA) & 0x20) == 0) {};
}


SIGNAL(SIG_ADC){
static int ctr1;
static char lbyte,hbyte;
ctr1++;
lbyte = inp(ADCL);
hbyte = inp(ADCH);

if (ctr1>=1000){
putchar(lbyte);
//putchar('A');
ctr1 = 0;
}


outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
(ADPS0),ADCSR);
// Internal Vref, right adjust
// Enable ADC interrupts, Clock/128
}


SIGNAL(SIG_UART_RECV){
char ch = inp(UDR);
putchar(ch);
}

SIGNAL(SIG_OVERFLOW0){
static int ctr;
ctr++;

if (ctr>=10){
//putchar('O');
ctr = 0;
}

}

int main(){
int i,j;

outp(BV(TOIE0),TIMSK); // Enable TCNT0
outp(0x00,TCNT0); // Reset TCNT00, CLK/1024
outp(BV(CS02)|BV(CS00), TCCR0);

outp(0x00, UCSRA); // USART:
outp(0x98, UCSRB); // USART: RxIntEnable|RxEnable|TxEnable
outp(0x86, UCSRC); // USART: 8bit, no parity
outp(0x00, UBRRH); // USART: 38400 @ 8MHz
outp(12, UBRRL); // USART: 38400 @ 8MHz

/*outp(0xce, ADMUX); // Internal Vref, right adjust, read 1.22V
(Vbg)*/
outp(BV(REFS1)|BV(REFS0)|BV(MUX1),ADMUX); //ADC2

// Enable ADC interrupts, Clock/128
outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
(ADPS0),ADCSR);

putchar('M');

sei();

while (1) {

/* putchar('L'); */
for(i = 0;i<10000;i++){
j = 1+1;
}

}
}

You don't say much about your circuit.  Are you using a TTL-to-RS232 
converter chip such as the 1488-1489 or MAX232?

Some people overlook these and wonder why their RS232 equipment isn't 
decoding the TTL source.

Zack

On 9 Mar 2007, englsprogeny wrote:

> Hi everyone.
> 
> I am trying to get an ATMEGA8 to talk to a terminal app on my PC by
> RS232. I have used the compiler [WinAVR] and programmer [PONY ISP]
> to compile and run other programs so I know that these parts of the
> issue are OK.
> 
> Here is the source....
> 
> 
> 
> Any ideas?
>

Do you have RS232 level shifting hardware?

DLC

englsprogeny wrote:
> Hi everyone.
> 
> I am trying to get an ATMEGA8 to talk to a terminal app on my PC by
> RS232. I have used the compiler [WinAVR] and programmer [PONY ISP]
> to compile and run other programs so I know that these parts of the
> issue are OK.
> 
> Here is the source....
> 
> 
> 
> Any ideas?
> 
> 
> I have an 8Mhz oscillator
> 
> Note: if anyone has simpler source with makefile please send it to
> me. Thanks
> 
> 
> 
> * >simcom -38400 /dev/ttyS0 */
> 
> #include <avr/io.h>
> #include <avr/signal.h>
> #include <avr/interrupt.h>
> 
> static void putchar(unsigned char ch){
> while ((inp(UCSRA) & 0x20) == 0) {};
> outp(ch, UDR);
> while ((inp(UCSRA) & 0x20) == 0) {};
> }
> 
> 
> SIGNAL(SIG_ADC){
> static int ctr1;
> static char lbyte,hbyte;
> ctr1++;
> lbyte = inp(ADCL);
> hbyte = inp(ADCH);
> 
> if (ctr1>=1000){
> putchar(lbyte);
> //putchar('A');
> ctr1 = 0;
> }
> 
> 
> outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
> (ADPS0),ADCSR);
> // Internal Vref, right adjust
> // Enable ADC interrupts, Clock/128
> }
> 
> 
> SIGNAL(SIG_UART_RECV){
> char ch = inp(UDR);
> putchar(ch);
> }
> 
> SIGNAL(SIG_OVERFLOW0){
> static int ctr;
> ctr++;
> 
> if (ctr>=10){
> //putchar('O');
> ctr = 0;
> }
> 
> }
> 
> int main(){
> int i,j;
> 
> outp(BV(TOIE0),TIMSK); // Enable TCNT0
> outp(0x00,TCNT0); // Reset TCNT00, CLK/1024
> outp(BV(CS02)|BV(CS00), TCCR0);
> 
> outp(0x00, UCSRA); // USART:
> outp(0x98, UCSRB); // USART: RxIntEnable|RxEnable|TxEnable
> outp(0x86, UCSRC); // USART: 8bit, no parity
> outp(0x00, UBRRH); // USART: 38400 @ 8MHz
> outp(12, UBRRL); // USART: 38400 @ 8MHz
> 
> /*outp(0xce, ADMUX); // Internal Vref, right adjust, read 1.22V
> (Vbg)*/
> outp(BV(REFS1)|BV(REFS0)|BV(MUX1),ADMUX); //ADC2
> 
> // Enable ADC interrupts, Clock/128
> outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
> (ADPS0),ADCSR);
> 
> putchar('M');
> 
> sei();
> 
> while (1) {
> 
> /* putchar('L'); */
> for(i = 0;i<10000;i++){
> j = 1+1;
> }
> 
> }
> }
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 

-- 
---------------------------------------
Dennis Clark    TTT Enterprises
---------------------------------------

Some things to check - how does your library implement outp() and inp()
- do they hard code to assembler inp and outp instructions, or are they
C macros that do the right thing when the address > 0x3F? (The machine
instructions inp and outp only work on the lowest 64 bytes of the IO
space, all registers outside the lowest 64 IO space registers must be
addressed as regular RAM [even though they are still IO registers.])

outp(0x00, UCSRA); // USART:
outp(0x98, UCSRB); // USART: RxIntEnable|

RxEnable|TxEnable
outp(0x86, UCSRC); // USART: 8bit, no parity
outp(0x00, UBRRH); // USART: 38400 @ 8MHz
outp(12, UBRRL); // USART: 38400 @ 8MHz

You are enabling the transmitter and receiver and then configuring the
port. Good practice to get into on UART's is do all configuration with
the Transmitter and Receiver disabled.

If you would like some definitely working routines, take the ones out of
the ATmega8's datasheet. Initialization routines are page 139, transmit
routines are on page 140, polling receive routines are on page 143.

AVR Appnote 306 - AVR306 provides sample code for the 8515 - this
should, at most, just need some registers renamed.

Also, if you are testing un-proven hardware, you may want to setup main
to just continuously send the same character or a NULL. You can then
hook up a frequency counter, or a LED pulled up to VCC, to see if it
really is transmitting something from the MCU pin, maybe the problem is
in the circuitry and not the MCU?

John C

englsprogeny wrote:

>
> Hi everyone.
>
> I am trying to get an ATMEGA8 to talk to a terminal app on my PC by
> RS232. I have used the compiler [WinAVR] and programmer [PONY ISP]
> to compile and run other programs so I know that these parts of the
> issue are OK.
>
> Here is the source....
>
> Any ideas?
>
> I have an 8Mhz oscillator
>
> Note: if anyone has simpler source with makefile please send it to
> me. Thanks
>
> * >simcom -38400 /dev/ttyS0 */
>
> #include <avr/io.h>
> #include <avr/signal.h>
> #include <avr/interrupt.h>
>
> static void putchar(unsigned char ch){
> while ((inp(UCSRA) & 0x20) == 0) {};
> outp(ch, UDR);
> while ((inp(UCSRA) & 0x20) == 0) {};
> }
>
> SIGNAL(SIG_ADC){
> static int ctr1;
> static char lbyte,hbyte;
> ctr1++;
> lbyte = inp(ADCL);
> hbyte = inp(ADCH);
>
> if (ctr1>=1000){
> putchar(lbyte);
> //putchar('A');
> ctr1 = 0;
> }
>
> outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
> (ADPS0),ADCSR);
> // Internal Vref, right adjust
> // Enable ADC interrupts, Clock/128
> }
>
> SIGNAL(SIG_UART_RECV){
> char ch = inp(UDR);
> putchar(ch);
> }
>
> SIGNAL(SIG_OVERFLOW0){
> static int ctr;
> ctr++;
>
> if (ctr>=10){
> //putchar('O');
> ctr = 0;
> }
>
> }
>
> int main(){
> int i,j;
>
> outp(BV(TOIE0),TIMSK); // Enable TCNT0
> outp(0x00,TCNT0); // Reset TCNT00, CLK/1024
> outp(BV(CS02)|BV(CS00), TCCR0);
>
> outp(0x00, UCSRA); // USART:
> outp(0x98, UCSRB); // USART: RxIntEnable|RxEnable|TxEnable
> outp(0x86, UCSRC); // USART: 8bit, no parity
> outp(0x00, UBRRH); // USART: 38400 @ 8MHz
> outp(12, UBRRL); // USART: 38400 @ 8MHz
>
> /*outp(0xce, ADMUX); // Internal Vref, right adjust, read 1.22V
> (Vbg)*/
> outp(BV(REFS1)|BV(REFS0)|BV(MUX1),ADMUX); //ADC2
>
> // Enable ADC interrupts, Clock/128
> outp(BV(ADEN)|BV(ADSC)|BV(ADIE)|BV(ADPS2)|BV(ADPS1)|BV
> (ADPS0),ADCSR);
>
> putchar('M');
>
> sei();
>
> while (1) {
>
> /* putchar('L'); */
> for(i = 0;i<10000;i++){
> j = 1+1;
> }
>
> }
> }
>
>