166
4317I–AVR–01/08
AT90PWM2/3/2B/3B
• Bit 7:6 – PPRE01:0 : PSC 0 Prescaler Select
This two bits select the PSC input clock division factor. All generated waveform will be modified
by this factor.
• Bit 5 – PBFM0 : Balance Flank Width Modulation
When this bit is clear, Flank Width Modulation operates on On-Time 1 only.
When this bit is set, Flank Width Modulation operates on On-Time 0 and On-Time 1.
• Bit 4 – PAOC0B : PSC 0 Asynchronous Output Control B
When this bit is set, Fault input selected to block B can act directly to PSCOUT01 output. See
Section “PSC Input Configuration”, page 147.
• Bit 3 – PAOC0A : PSC 0 Asynchronous Output Control A
When this bit is set, Fault input selected to block A can act directly to PSCOUT00 output. See
Section “PSC Input Configuration”, page 147.
• Bit 2 – PARUN0 : PSC 0 Autorun
When this bit is set, the PSC 0 starts with PSC2. That means that PSC 0 starts :
•
when PRUN2 bit in PCTL2 is set,
•
or when PARUN2 bit in PCTL2 is set and PRUN1 bit in PCTL1 register is set.
Thanks to this bit, 2 or 3 PSCs can be synchronized (motor control for example)
• Bit 1 – PCCYC0 : PSC 0 Complete Cycle
When this bit is set, the PSC 0 completes the entire waveform cycle before halt operation
requested by clearing PRUN0. This bit is not relevant in slave mode (PARUN0 = 1).
• Bit 0 – PRUN0 : PSC 0 Run
Writing this bit to one starts the PSC 0.
When set, this bit prevails over PARUN0 bit.
16.25.12 PSC 1 Control Register – PCTL1
Table 16-14. PSC 0 Prescaler Selection
PPRE01
PPRE00
Description PWM2/3
Description PWM2B/3B
0
0
No divider on PSC input clock
No divider on PSC input clock
0
1
Divide the PSC input clock by 4
Divide the PSC input clock by 4
1
0
Divide the PSC input clock by 16
Divide the PSC input clock by 32
1
1
Divide the PSC clock by 64
Divide the PSC clock by 256
Bit
7
6
5
4
3
2
1
0
PPRE11
PPRE10
PBFM1
PAOC1B
PAOC1A
PARUN1
PCCYC1
PRUN1
PCTL1
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
