DEMO9S12XEP100 Freescale Semiconductor, DEMO9S12XEP100 Datasheet - Page 709

• Manufacturer Part Number: DEMO9S12XEP100
• Description: BOARD DEMO FOR MC9S12XEP100
• Manufacturer: Freescale Semiconductor
• Type: MCUr

Specifications of DEMO9S12XEP100

• Contents: Board, Cables, CD
• Processor To Be Evaluated: MC9S12XEP100
• Data Bus Width: 16 bit
• Interface Type: RS-232
• Silicon Manufacturer: Freescale
• Core Architecture: S12
• Core Sub-architecture: S12
• Silicon Core Number: MC9S12
• Silicon Family Name: S12XE
• Rohs Compliant: Yes
• For Use With/related Products: MC9S12XEP100
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Read: Anytime
Write: Anytime
19.3.2.14 PWM Channel Duty Registers (PWMDTYx)
There is a dedicated duty register for each channel. The value in this register determines the duty of the
associated PWM channel. The duty value is compared to the counter and if it is equal to the counter value
a match occurs and the output changes state.
The duty registers for each channel are double buffered so that if they change while the channel is enabled,
the change will NOT take effect until one of the following occurs:
In this way, the output of the PWM will always be either the old duty waveform or the new duty waveform,
not some variation in between. If the channel is not enabled, then writes to the duty register will go directly
to the latches as well as the buffer.
See
To calculate the output duty cycle (high time as a% of period) for a particular channel:
Freescale Semiconductor
Module Base + 0x0014 = PWMPER0, 0x0015 = PWMPER1, 0x0016 = PWMPER2, 0x0017 = PWMPER3
Module Base + 0x0018 = PWMPER4, 0x0019 = PWMPER5, 0x001A = PWMPER6, 0x001B = PWMPER7
Because of an order from the United States International Trade Commission, BGA-packaged product lines and partnumbers
Reset
indicated here currently are not available from Freescale for import or sale in the United States prior to September 2010
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Section 19.4.2.3, “PWM Period and Duty”
W
R
The effective period ends
The counter is written (counter resets to $00)
The channel is disabled
Polarity = 0 (PPOL x =0)
Polarity = 1 (PPOLx = 1)
Duty Cycle = [(PWMPERx-PWMDTYx)/PWMPERx] * 100%
Bit 7
1
7
Reads of this register return the most recent value written. Reads do not
necessarily return the value of the currently active duty due to the double
buffering scheme.
Depending on the polarity bit, the duty registers will contain the count of
either the high time or the low time. If the polarity bit is one, the output starts
high and then goes low when the duty count is reached, so the duty registers
contain a count of the high time. If the polarity bit is zero, the output starts
low and then goes high when the duty count is reached, so the duty registers
contain a count of the low time.
Figure 19-15. PWM Channel Period Registers (PWMPERx)
1
6
6
MC9S12XE-Family Reference Manual Rev. 1.23
5
1
5
for more information.
NOTE
NOTE
1
4
4
1
3
3
Chapter 19 Pulse-Width Modulator (S12PWM8B8CV1)
2
1
2
1
1
1
Bit 0
1
0
709