8-bit PWM (0–255)
| Value | Duty | Avg @ 5 V | Avg @ 3.3 V |
|---|---|---|---|
| 0 | 0 % | 0 V | 0 V |
| 32 | 12.5 % | 0.625 V | 0.41 V |
| 64 | 25 % | 1.25 V | 0.83 V |
| 96 | 37.5 % | 1.875 V | 1.24 V |
| 128 | 50 % | 2.5 V | 1.65 V |
| 160 | 62.5 % | 3.125 V | 2.06 V |
| 192 | 75 % | 3.75 V | 2.48 V |
| 224 | 87.5 % | 4.375 V | 2.89 V |
| 255 | 100 % | 5.0 V | 3.3 V |
10-bit PWM (0–1023)
| Value | Duty | Notes |
|---|---|---|
| 0 | 0 % | |
| 102 | 10 % | |
| 256 | 25 % | |
| 512 | 50 % | |
| 768 | 75 % | |
| 1023 | 100 % | Full on |
Formulas
| Duty D | = value / max_count |
|---|---|
| Avg voltage | = D · (V_high − V_low) + V_low |
| Top count (timer) | = F_clk / (prescaler × F_pwm) |
| Usable bits | = log₂(top_count + 1) |
Notes
- At very low duty (< 1% of top), minor clocking errors dominate — use a higher-resolution timer.
- Motor / LED drivers often have a minimum on-time — below it the output stays off.
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