ST7LITE2, PWM programming in C

[delser9]

Posted on June 27, 2003 at 07:27

ST7LITE2, PWM programming in C

[delser9]

Posted on June 26, 2003 at 11:34

Using the ST7LITE2 ARTimer in PWM mode:

1) Is there any order in writing the DCRxx, ATCSR, ATRxx and PWMCR registers?

2) My program looks like that:

PADDR=0x04; // PA2 (PWM0) = output

PAOR=0x04; // PA2 = pullup

SetBit(ATCSR,FOUR); // Counter Clk = fCPU

ClrBit(ATCSR,THREE);

ATRH=0x00;

ATRL=0x00;

DCR0H=0x05;

PWMCR=0x01; // PWM0 enable

What is wrong with that? There is no signal at the pin which is connected to a LED on the in-DART-STX Demo-board. Do I need the Overflow/Compare interrupts?

Are there any examples for ST7Lite2 PWM mode in C?

Thanks for any help!

[bleumers_j]

Posted on June 26, 2003 at 11:48

Hi,

When you write ''DCR0H=0x05;'', the 0x05 are placed into temporaly registers, not in the ''real'' PWM register.

By adding TRANCR=0x01 after the DCR0H=0x05 the data is copied into the ''real'' PWM registers. Do not forget to do this later on in your program every time a PWM value has to be changed!

Maybe you should place ''PWMCR=0x01'' before the DCR0H=0x05. But i'm not sure.

When it still doesn't work i can give a part of code you can use. Just ask.

Greets.

[delser9]

Posted on June 26, 2003 at 12:20

Hello joble

Thank you very much for your help!

Indeed, it's important to set the TRAN bit, what i didn't! (With the LITE0, that ARTimer is quite different, unfortunately I have only LITE0 examples). But even with that bit set, it still doesn't work. I tried also to toggle position between the PWMCR and the DCR0H line, but there is still no effect!

For the 'DCRxx' lines I disable the interrupts, and enable afterwards, but that doesn't help neither.

Do have any other ideas?

Thanks again, and have a nice evening!

[bleumers_j]

Posted on June 26, 2003 at 12:38

This should work, it's copied from a program that works fine. I do not see any difference with your program.

init:

PADDR=0x7F;

PAOR=0x7F;

ATCSR=0x10;

ATRH=0x00;

ATRL=0x00;

PWMCR=0x15;

in the program:

DCR0H=10;

DCR0L=128;

TRANCR=0x01;

Hope this helps...

[delser9]

Posted on June 27, 2003 at 04:32

Thank you very much for your help. You thought me about the TRAN bit. Although I have exactly the same program as you, it still doesn't work.

Even with a new uController it is still the same. Maybe there is someone out there from ST interested in helping their costumer? Up to now ST just pointed me to this forum.

[delser9]

Posted on June 27, 2003 at 07:11

Problem partially resolved!

The PWM function works well on PWM1 but not on PWM0, although they have absolutely the same configuration (Soft-and Hardware)!

Anybody an idea why it is so?

[bleumers_j]

Posted on June 27, 2003 at 07:27

Hi,

Maybe something wrong with the definition of DCR0H and DCROL? Maybe a stupid idea, but i can't find another possible reason.

Part of the IO7Flite2.h file:

@tiny volatile char DCR0H @0x17; /* PWM 0 Duty Cycle Register High */

@tiny volatile char DCR0L @0x18; /* PWM 0 Duty Cycle Register Low */

@tiny volatile char DCR1H @0x19; /* PWM 0 Duty Cycle Register High */

@tiny volatile char DCR1L @0x1A; /* PWM 0 Duty Cycle Register Low */

@tiny volatile char DCR2H @0x1B; /* PWM 0 Duty Cycle Register High */

@tiny volatile char DCR2L @0x1C; /* PWM 0 Duty Cycle Register Low */

@tiny volatile char DCR3H @0x1D; /* PWM 0 Duty Cycle Register High */

@tiny volatile char DCR3L @0x1E; /* PWM 0 Duty Cycle Register Low

Or a hardware fault (try swapping the pins).

Greets.