ATtiny45 PWM Frequency Selection

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21

johnamon:
To achieve 32kHz, I need to divide the system 8MHz clock by 256 (prescaler of 256).

No, you don't need to a prescaler of 256, you need a prescaler of 1. If you use one of the 8-bit counter/timers with its maximum TOP value of 255 (as is usual when using it to generate a PWM signal), then the counter is already dividing by either 256 or 512 (depending on the mode you select), giving you a frequency close to 32KHz or 16kHz.

22

oK - I can see from Page 76 of the datasheet that in Fast Mode PWM the frequency pre-scaler should be 1 as the system clock is already divided by 256.....

Thank you again dc42 - this is a fair bit more complicated than I expected when I was ordering bits on the Farnell website, I couldn't have got here without you guys!