Help by coding a PWM_WRITE procedure

[pascalbythree]

https://wiki.freepascal.org/AVR_Embedded_Tutorial_-_Analog_Write

Code: Pascal  [Select][+][-]

1.   var
2.    i : integer;  // Loop counter
3.  begin
4.    // Configure PD5 and PD6 as outputs
5.    DDRD := %01100000;
6.  
7.    // Configure PD5 and PD6 in PWM mode
8.    TCCR0A := (%10 shl COM0A) or (%10 shl COM0B) or (1 shl WGM0);
9.  
10.    // Enable timer 0, clock / 1024
11.    TCCR0B := TCCR0B or %101;
12.  
13.    // Main loop that continuously makes the LEDs brighter and darker
14.    repeat
15.      for i := 0 to 255 do
16.        begin
17.          OCR0A := i;
18.          OCR0B := 255 - i;
19.          sleep;
20.      end;
21.  
22.      for i := 0 to 255 do
23.        begin
24.          OCR0A := 255 - i;
25.          OCR0B := i;
26.          sleep;
27.        end;
28.    until False;
29.  end.

Can somebody help me out with this procedure, i have to cat it over to this:

Code: Pascal  [Select][+][-]

1. procedure SETPWM(Port:Char; PIN:byte; Value:integer);
2. begin
3.  // ???
4. end;

I Want to use PB2 to PWM output. For the Attiny2313A. Great thanks...

Its to control the FAN Speed in this project. See Photo!

[ccrause]

Can somebody help me out with this procedure, i have to cat it over to this:

Code: Pascal  [Select][+][-]

1. procedure SETPWM(Port:Char; PIN:byte; Value:integer);
2. begin
3.  // ???
4. end;

I Want to use PB2 to PWM output. For the Attiny2313A. Great thanks...

One way of doing this is to check for valid port & pin combinations, then configure the appropriate timer attached to that pin:

Code: Pascal  [Select][+][-]

1. procedure SETPWM(Port: Char; pin: byte; value: uint16);
2. begin
3.   if (Port = 'B') and (pin = 2) then
4.   begin
5.   // configure timer 0, channel A
6.     TCCR0A := TCCR0A or (%10 shl COM0A) or (1 shl WGM0);
7.     TCCR0B := TCCR0B or %101;
8.     OCR0A := byte(value);
9.   end
10.   else if (Port = 'A') and (pin = 5) then
11.   begin
12.   // configure timer 0, channel B
13.   end
14.   else if (Port = 'B') and (pin = 3) then
15.   begin
16.   // configure timer 1, channel A
17.   end
18.   else if (Port = 'B') and (pin = 4) then
19.   begin
20.   // configure timer 1, channel B
21.   end
22.   else
23.     // Do nothing, or output some error
24. end;

This is an outline of one possible method of coding the SETPWM function.  This is the bare minimum functionality, more code would be required to make this robust.

While a SETPWM procedure may seem helpful, it will always generate code to configure all four PWM pins, even if you only use a single PWM pin. Also note that you will end up with some repeated code in the different if branches.

Note that timer0 is 8 bit, while timer1 is 16 bit.  This means that this generic SETPWM function has to range check the value parameter depending on which timer is used.  Perhaps an unsigned type for value is more useful since the timer only works with positive or zero values.

While Arduino has made this kind of abstraction popular, it comes at the cost of larger code size and slower execution because of the extra code required for the mapping.  Just think about the complication of switching off PWM on a pin.  Do you just disable the OCn output to the pin, but keep the timer running? Or do you check if both OCnA and OCnB are disabled before disabling the timer?  All of this logic requires extra code, which is not required if you know you only use fixed PWM pins in your project.

A general recommendation on the AVRfreaks forum is that you typically use fixed pins in a project, so just configure those pins specifically and be done.

[pascalbythree]

Tank you very much! it already got to work ! Now i am going to work on the speeds...

What number to change for higher PWM speeds? It seems that i need a higher speed to PWM to my mosfet driver IC. You can hear it a little in the noise of the fan.

Wait got it already, no FASTPWM is needed  value: uint16 is not a byte :-) Woops 

[pascalbythree]

Code: Pascal  [Select][+][-]

1.   // configure timer 0, channel A
2.     TCCR0A := TCCR0A or (%10 shl COM0A) or (1 shl WGM0);
3.     TCCR0B := TCCR0B or %101;
4.     OCR0A := byte(value);

Can anybody help me out changing this code for the PB1 pin on a Atmega328P ?

To: OC1A

Greets, PascalByThree

[pascalbythree]

Yay! It got to work already!

Code: Pascal  [Select][+][-]

1.    // Configure PD5 and PD6 in PWM mode
2.    TCCR1A := (%10 shl COM1A) or (%10 shl COM1B) or (1 shl WGM1);
3.  
4.    // Enable timer 0, clock / 1024
5.    TCCR1B := TCCR1B or %101;
6.  
7.    OCR1A := 125;

Stil thank you...