MM912H634DM1AER2 Freescale Semiconductor, MM912H634DM1AER2 Datasheet - Page 105

• Manufacturer Part Number: MM912H634DM1AER2
• Description: 16-bit Microcontrollers - MCU 64KS12 LIN2XLS/HS ISENSE
• Manufacturer: Freescale Semiconductor

Specifications of MM912H634DM1AER2

• Rohs: yes
• Core: HCS12
• Processor Series: MM912F634
• Data Bus Width: 16 bit
• Maximum Clock Frequency: 20 MHz
• Program Memory Size: 32 KB
• Data Ram Size: 2 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 5.5 V to 18 V
• Operating Temperature Range: - 40 C to + 105 C
• Package / Case: LQFP-48
• Mounting Style: SMD/SMT
• A/d Bit Size: 10 bit
• A/d Channels Available: 15
• Interface Type: SPI
• Maximum Operating Temperature: + 105 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 15
• Number Of Timers: 1
• Program Memory Type: Flash
• Supply Voltage - Max: 18 V
• Supply Voltage - Min: 5.5 V

Functional Description and Application Information
The output waveform generated is shown in
4.13.4.2.6
For a center aligned output mode selection, set the CAEx bit (CAEx = 1) in the PWMCTL register, and the corresponding PWM
output will be center aligned.
The 8-bit counter operates as an up/down counter in this mode, and is set to up whenever the counter is equal to $00. The counter
compares to two registers, a duty register and a period register, as shown in the block diagram in
counter matches the duty register, the output flip-flop changes state, causing the PWM waveform to also change state. A match
between the PWM counter and the period register changes the counter direction from an up-count to a down-count. When the
PWM counter decrements and matches the duty register again, the output flip-flop changes state, causing the PWM output to
also change state. When the PWM counter decrements and reaches zero, the counter direction changes from a down-count back
to an up-count, and a load from the double buffer period and duty registers to the associated registers is performed, as described
in
down to 0. Thus the effective period is PWMPERx*2.
To calculate the output frequency in center aligned output mode for a particular channel, take the selected clock source frequency
for the channel (A, B, SA, or SB) and divide it by twice the value in the period register for that channel.
Freescale Semiconductor
Section 4.13.4.2.3, “PWM Period and
•
•
PWMx Frequency = Clock (A, B, SA, or SB) / (2*PWMPERx)
PWMx Duty Cycle (high time as a% of period):
— Polarity = 0 (PPOLx = 0)
Duty Cycle = [(PWMPERx-PWMDTYx)/PWMPERx] * 100%
— Polarity = 1 (PPOLx = 1)
Duty Cycle = [PWMDTYx / PWMPERx] * 100%
PPOLx = 0
PPOLx = 1
Center Aligned Outputs
Changing the PWM output mode from left aligned to center aligned output (or vice versa)
while channels are operating can cause irregularities in the PWM output. It is recommended
to program the output mode before enabling the PWM channel.
E = 100 µs
Figure 28. PWM Left Aligned Output Example Waveform
PWMDTYx
Figure 29. PWM Center Aligned Output Waveform
Duty"”. The counter counts from 0 up to the value in the period register and then back
Figure
PWMPERx
Period = 400 µs
28.
Period = PWMPERx*2
Duty Cycle = 75%
NOTE
PWMPERx
PWM Control Module (PWM8B2C)
PWMDTYx
Figure
26. When the PWM
MM912F634
105