MC68HC908QC16_07 Datasheet, PDF (121/274 Pages) Freescale Semiconductor, Inc – Microcontrollers

PS3-PS0
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Table 12-1. Prescaler Selection
PWU Counter Clock Source
(PWU Clock Divided by:)
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
Nominal Period
(@ 32kHz)
31.25 μs
62.5 μs
125 μs
250 μs
500 μs
1 ms
2 ms
4 ms
8 ms
16 ms
32 ms
64 ms
128 ms
256 ms
512 ms
1s
Registers
12.8.3 Periodic Wakeup Modulo Register
The PWU modulo register contains the modulo value for the counter. When the counter reaches the
modulo value, the PWU flag (PWUF) becomes set, and the counter resumes counting from $00 at the
next PWU clock. If PWUIE is set, a PWU interrupt is requested.The value in the PWUMOD register and
the selected prescaler output determine the frequency of the periodic interrupt. The frequency of the
periodic interrupt can be calculated by multiplying the prescaler period (see Table 12-1) by the value in
the modulo register.
NOTE
The PWUMOD register can only be written to when PWUON is clear.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 12-4. Periodic Wakeup Modulo Register (PWUMOD)
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 3
Freescale Semiconductor
121