Pwm on tiny13

naseerak · Joined: 08 Nov 2008 Posts: 138

Hi
I want to generate 20khz of pwm on the pwm outputs of tiny but with a 10ms gape between the two signals, Is it possible with interrupt or the only option is WAITMS command.

$regfile = "attiny13.dat"
$crystal = 9600000
$hwstack = 16
$swstack = 16
$framesize = 16

'----------------------------------------------------------------------------
Config Portb = Output

Config Timer0 = Timer , Prescale = 1 , Clear_timer = 1 , Compare_a = Toggle , Compare_b = Toggle

Config Adc = Single , Prescaler = Auto , Reference = Internal

'-----------------------------------------------------------------------------
Do

Compare0a = 64
Compare0b = 0

Waitms 10

Compare0b = 64

Loop

End

(BASCOM-AVR version : 2.0.7.7 )

naseerak · Joined: 08 Nov 2008 Posts: 138

$regfile = "attiny13.dat"
$crystal = 9600000
$hwstack = 16
$swstack = 16
$framesize = 16

Config Portb = Output

Config Timer0 = Pwm , Prescale = 1 , Compare A Pwm = Clear Down , Compare B Pwm = Clear Down

Do

Gosub Halfcycle_1

Loop
End

Halfcycle_1:
Pwm0b = 0

Pwm0a = 128
Waitms 1
Pwm0a = 202
Waitms 1
Pwm0a = 249
Waitms 1
Pwm0a = 249
Waitms 1
Pwm0a = 202
Waitms 1
Pwm0a = 128
Waitms 1
Pwm0a = 53
Waitms 1
Pwm0a = 6
Waitms 1
Pwm0a = 6
Waitms 1
Pwm0a = 53
Waitms 1
Pwm0a = 128
Gosub Halfcycle_2
Return

Halfcycle_2:
Pwm0a = 0

Pwm0b = 128
Waitms 1
Pwm0b = 202
Waitms 1
Pwm0b = 249
Waitms 1
Pwm0b = 249
Waitms 1
Pwm0b = 202
Waitms 1
Pwm0b = 128
Waitms 1
Pwm0b = 53
Waitms 1
Pwm0b = 6
Waitms 1
Pwm0b = 6
Waitms 1
Pwm0b = 53
Waitms 1
Pwm0b = 128
Return

This is my new code with 10 element table as tiny13 has no other timer to interrupt and pick a value from the table this is why I am doing it with waitms command dividing the 10ms time for each half cycle equally in 10 segments. but I am not getting sine wave on my Proteus Oscilloscope I suspect I am missing a suitable filter on the out put but then what should be the values of filter elements to filter out the unwanted harmonics.

kimmi · Joined: 24 Feb 2006 Posts: 1922 Location: Denmark

hi
you can try with rc filter Res 10K and cap 0.1uF on both pwm output
use channel A and B in proteus
on A channel select A+B then you see if its more like sinus

naseerak · Joined: 08 Nov 2008 Posts: 138

Yes it worked!
BTW is there any better way of generating spwm on Tiny13?