在 atmega32 中使用 8 位的 32khz pwm

Question

I'm learning coding in a robotics team . My seniors give me tasks and I complete it .We code on ATMEGA32 microcontroller using atmel studio (c language).Recent task was to generate a 32khz frequency pwm .I did the task using 16 bit timers as I thought its not possible with 8 bit as there weren't any suitable prescalers (in fast mode you get 62 khz with no prescalers and the next prescalers is f/8 !!) . But my senior says it is possible in 8 bit using any mode !! Please tell me how to obtain 32khz with 8 bit timer because I don't see how it is possible unless I change the clock frequency itself (which isn't allowed). Fast mode is preferable. Do I have to do something with the TCNT0 register??

Answer 1

you can generate an 32kHz with an 8 bit timer on 16MHz by using the compare register twice per cycle, to get 32kHz you can use the clock divider to /8 and count to from 0 62 (which gives you about 32.2kHz) so, first you set the compare register OCR0 to your pwm value which should be between 0 to 61, and after you get a compare interrupt on OCF0 you change OCR to 62 and wait the next interrupt on OCF0. There, you clear the TCNT0 to start the process again (or maybe set this second interrupt to use the CTC mode but you still need to get inside the interrupt to set the next interrupt on normal mode)...

basically there's no way to setup the waveform generator to do a 32KHz PWM signal automatically on the ATmega32 on 16MHz, but you can still use the timer module with it's compare register to generate the signal you need...