PFS122
8bit MTP MCU with 12-bit R-Type ADC
5.7.2 Using the Timer2 to generate 8-bit PWM waveform
If 8-bit PWM mode is selected, it should set tm2c[1]=1 and tm2s[7]=0, the frequency and duty cycle of
output waveform can be summarized as below:
Frequency of Output = Y ÷ [256 × S1 × (S2+1) ]
Duty of Output = [( K＋1 ) ÷ 256]×100%
Where, Y = tm2c[7:4] : frequency of selected clock source
K = tm2b[7:0] : bound register in decimal
S1= tm2s[6:5] : pre-scalar (S1= 1, 4, 16, 64)
S2 = tm2s[4:0] : scalar register in decimal (S2= 0 ~ 31)
Example 1:
tm2c = 0b0001_1010, Y=8MHz
tm2b = 0b0111_1111, K=127
tm2s = 0b0_00_00000, S1=1, S2=0
frequency of output = 8MHz ÷ ( 256 × 1 × (0+1) ) = 31.25KHz
duty of output = [(127+1) ÷ 256] × 100% = 50%
Example 2:
tm2c = 0b0001_1010, Y=8MHz
tm2b = 0b0111_1111, K=127
tm2s = 0b0_11_11111, S1=64, S2=31
frequency of output = 8MHz ÷ ( 256 × 64 × (31+1) ) = 15.25Hz
duty of output = [(127+1) ÷ 256] × 100% = 50%
Example 3:
tm2c = 0b0001_1010, Y=8MHz
tm2b = 0b1111_1111, K=255
tm2s = 0b0_00_00000, S1=1, S2=0
PWM output keep high
duty of output = [(255+1) ÷ 256] × 100% = 100%
Example 4:
tm2c = 0b0001_1010, Y=8MHz
tm2b = 0b0000_1001, K = 9
tm2s = 0b0_00_00000, S1=1, S2=0
frequency of output = 8MHz ÷ ( 256 × 1 × (0+1) ) = 31.25KHz
duty of output = [(9+1) ÷ 256] × 100% = 3.9%
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PDK-DS-PFS122-EN_V000-May 28, 2020
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