mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 138

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Pulse-Width Modulator (PWM)
11.2.15 Port P Data Direction Register
Read: Anytime
Write: Anytime
DDRP determines pin direction of port P when used for general-purpose I/O. When cleared, I/O pin is
configured for input. When set, I/O pin is configured for output.
11.3 PWM Boundary Cases
The boundary conditions for the PWM channel duty registers and the PWM channel period registers
cause the results shown in
11.4 Using the Output Compare 7 Feature to Generate a PWM
This timer exercise is intended to utilize the output compare function along with the output compare 7 new
feature to generate a PWM waveform. It must allow for the duty used to drive a DC motor on the UDLP1
board. The registers must be initialized accordingly TC7 = period and TC5 = high time (duty cycle). See
Figure
138
11-28.
Address: $0057
To verify program is working the DC motor must turn, the frequency, high
time, and duty cycle must displayed on the LCD.
Reset:
Read:
Write:
DDP7
Bit 7
Figure 11-27. Port P Data Direction Register (DDRP)
0
≥PWPERx
≥PWPERx
PWDTYx
Table
$FF
$FF
—
—
Table 11-2. PWM Boundary Conditions
DDP6
11-2.
6
0
Figure 11-28. Example Waveform
M68HC12B Family Data Sheet, Rev. 9.1
PERIOD
DDP5
PWPERx
5
0
>$00
>$00
$00
$00
HIGH TIME
—
—
NOTE
DDP4
4
0
HIGH TIME = DUTY CYCLE
PPOLx
DDP3
1
0
1
0
1
0
3
0
DDP2
2
0
Output
High
High
High
Low
Low
Low
DDP1
1
0
Freescale Semiconductor
DDP0
Bit 0
0