Hardware manual

Rev. 3.0, 09/98, page 184 of 361

Table 9.3 PWM Timer Parameters for 10MHz System Clock

Internal Clock Frequency Resolution PWM Period PWM Frequency

φ/2 200ns 50µs 20kHz

φ/8 800ns 200µs 5kHz

φ/32 3.2µs 800µs 1.25kHz

φ/128 12.8µs 3.2ms 312.5Hz

φ/256 25.6µs 6.4ms 156.3Hz

φ/1024 102.4µs 25.6ms 39.1Hz

φ/2048 204.8µs 51.2ms 19.5Hz

φ/4096 409.6µs 102.4ms 9.8Hz

9.3 Operation

9.3.1 Timer Incrementation

The PWM clock source is created from the system clock (φ) by a prescaler. The timer counter

increments on a TCNT clock pulse generated from the falling edge of the prescaler output as

shown in figure 9.2.

N - 1

N + 1

Prescaler

output

TCNT clock

pulse

TCNT

Figure 9.2 TCNT Increment Timing