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This library allows you to use any available timer to produce a PWM output. The design intent is to control the pulse width and PWM period, with a maximum range of supported frequencies. It uses the Fast PWM method, but this may change to include the Phase correct PWM method.
ATtiny85 BUG - ATtiny85 datasheet errata (section 27.2.3, page 213) PWM output OC1B does not work correctly unless COM1A1 and COM1A0 are set to the same value as COM1B1 and COM1B0 respectively.
This is handle internally by the PWM library when you set the 1B register settings. e.g. pwm.set(1,'b',60000,2); // internally it sets [COM1A1 COM1A0] to [COM1B1 COM1B0]
| Chip | Timer0 | Timer1 | Timer2 | Timer3 | Timer4 | |
|---|---|---|---|---|---|---|
| 8b PS | 8b ePS | -- | -- | -- | ||
| ATtiny85 | A | D0 | D1 | -- | -- | -- |
| B | D1 | D3 | -- | -- | -- | |
| 8b PS | 16b PS | 8b PS | -- | -- | ||
| ATmega328p | A | D6# | D9 | D12* | -- | -- |
| B | D5 | D10 | D3 | -- | -- | |
| 8b PS | 8b PS | -- | 16b PS | 8b ePS | ||
| ATmega32u4 | A | D11 | D9 | -- | D5 | D13 |
| B | D3 | D10 | -- | -- | D10 | |
| C | -- | D11 | -- | -- | -- | |
| D | -- | -- | -- | -- | D6 |
8b/16b : 8 bit or 16 bit timer
PS/ePS : Regular prescalar, Extended prescalar selection
PS = [0,1,8,64,256,1024]
ePS = [0,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384]
# toggled output. The frequency is half the set frequency, the duty cycle is fixed at 50%
* same as #, but software PWM. It is implemented through the respective TIMERx_OVF_vect ISR
- I can be smarter when setting the PeriodRegister. I plan to use the ISR as a counter to implement a static correction table to add +0 or +1 to the ICRx or OCRx register.
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