Datasheet

114
7734Q–AVR–02/12
AT90PWM81/161
The waveform frequency is defined by the following equation:
12.7.2.2 Enhanced Mode
The Enhanced Mode uses the previously described method to generate a high resolution fre-
quency. Figure 12-13 gives an example of FWM with PBFMn1:0 = 00.
Figure 12-13. Enhanced mode, timing diagram.
The supplementary step in counting to generate f
b2
is added on the PSCn0 signal while needed
in the frame according to the fractional divider. See Table 12-6 on page 113.
The waveform frequency is defined by the following equations:
d is the fractional divider factor.
The FWM can be applied on different locations within the PSC output waveforms as defined per
Table 12-15 on page 138.
12.8 PSC Inputs
Part A or B of PSC has its own system to take into account one PSC n internal input. Each part
A or B is configured by the PSC n Input A/B Control Register (“PFRCnA - PSC n Input A Control
Register” on page 141 and “PFRCnB - PSC n Input B Control Register” on page 141) and the
PSC n Extended Configuration Register (see Section “PCNF2 - PSC 2 Configuration Register”,
page 136).
The PSC input module A is shown in Table 12-14 on page 115.
f
PSCn
1
PSCnCycle
------------------------------=
f
CLK_PSCn
OT0 OT1 DT0 DT1+++()
---------------------------------------------------------------------=
PSCOUTn0
T1
Period
PSCOUTn1
OT0
OT1
DT1
DT0
T2
OT0
OT1+1
DT1
DT0
DT0
f1
PSCn
1
T
1
-----
f
CLK_PSCn
OT0 OT1 DT0 DT1+++()
---------------------------------------------------------------------==
f2
PSCn
1
T
2
-----
f
CLK_PSCn
OT0 OT1 DT0 DT11++++()
------------------------------------------------------------------------------==
f
AVERAGE
d
16
------
f1
PSCn
×
16 d–
16
---------------
f2
PSCn
×+=