mc68hc908lb8 Freescale Semiconductor, Inc, mc68hc908lb8 Datasheet - Page 95

• Manufacturer Part Number: mc68hc908lb8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

10.4.2 Frequency Dithering on the HRP
The HRP provides frequency dithering between two signals whose periods differ by one HRPCLK cycle.
When the HRP is supplied with an 8 MHz clock, the difference between the period values is 125 ns.
The HRP provides a programmable number of dithering steps, up to a maximum of 32 steps. This results
in a maximum frequency resolution of 125/32 = 3.906 ns when using an 8 MHz clock.
Figure 10-5
32 dithering steps are chosen. In this example, the Period signal is output for 25% of the time, i.e. 8 of the
32 steps, and the Period+1 signal is output for 75% of the time, i.e. 24 of the 32 steps.
Freescale Semiconductor
AVERAGE
SIGNAL
shows the relationship between the two dithering frequencies and the output frequency when
0
13 kHz
10
10 kHz
20
Figure 10-4. Dithering Waveforms
10 kHz
30
MC68HC908LB8 Data Sheet, Rev. 1
20 kHz
40
1 CYCLE
50
60
70
80
20 kHz
90
100
Functional Description
% CYCLE
t
95