M68HC12B Datasheet, PDF (128/334 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pulse-Width Modulator (PWM)
11.2 PWM Register Descriptions
This section provides descriptions of the PWM registers.
11.2.1 PWM Clocks and Concatenate Register
Address: $0040
Bit 7
6
5
4
3
2
1
Bit 0
Read:
CON23
Write:
CON01
PCKA2
PCKA1
PCKA0
PCKB2
PCKB1
PCKB0
Reset: 0
0
0
0
0
0
0
0
Figure 11-4. PWM Clocks and Concatenate Register (PWCLK)
Read: Anytime
Write: Anytime
CON23 — Concatenate PWM Channels 2 and 3 Bit
When concatenated, channel 2 becomes the high-order byte and channel 3 becomes the low-order
byte. Channel 2 output pin is used as the output for this 16-bit PWM (bit 2 of port P). Channel 3
clock-select control bits determines the clock source.
0 = Channels 2 and 3 are separate 8-bit PWMs.
1 = Channels 2 and 3 are concatenated to create one 16-bit PWM channel.
CON01 — Concatenate PWM Channels 0 and 1 Bit
When concatenated, channel 0 becomes the high-order byte and channel 1 becomes the low-order
byte. Channel 0 output pin is used as the output for this 16-bit PWM (bit 0 of port P). Channel 1
clock-select control bits determine the clock source.
0 = Channels 0 and 1 are separate 8-bit PWMs.
1 = Channels 0 and 1 are concatenated to create one 16-bit PWM channel.
PCKA2–PCKA0 — Prescaler for Clock A Bits
Clock A is one of two clock sources which may be used for channels 0 and 1. These three bits
determine the rate of clock A, as shown in Table 11-1.
PCKB2–PCKB0 — Prescaler for Clock B Bits
Clock B is one of two clock sources which may be used for channels 2 and 3. These three bits
determine the rate of clock B, as shown in Table 11-1.
Table 11-1. Clock A and Clock B Prescaler
PCKA2 (PCKB2)
0
0
0
0
1
1
1
1
PCKA1 (PCKB1)
0
0
1
1
0
0
1
1
PCKA0 (PCKB0)
0
1
0
1
0
1
0
1
Value of Clock A (B)
E
E÷2
E÷4
E÷8
E ÷ 16
E ÷ 32
E ÷ 64
E ÷ 128
M68HC12B Family Data Sheet, Rev. 9.1
128
Freescale Semiconductor