AT80C51RA2 データシートの表示（PDF） - Atmel Corporation
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AT80C51RA2 Datasheet PDF : 86 Pages
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AT/TS8xC51Rx2
There are two additional registers associated with each of the PCA modules. They are CCAPnH
and CCAPnL and these are the registers that store the 16-bit count when a capture occurs or a
compare should occur. When a module is used in the PWM mode these registers are used to
control the duty cycle of the output (See Table 6-8 & Table 6-9)
Table 6-8. CCAPnH: PCA Modules Capture/Compare Registers High
CCAPnH Address
n=0-4
CCAP0H=0FAH
CCAP1H=0FBH
CCAP2H=0FCH
CCAP3H=0FDH
CCAP4H=0FEH
7
6
5
4
3
2
1
0
Reset value
0
0
0
0
0
0
0
0
Table 6-9. CCAPnL: PCA Modules Capture/Compare Registers Low
CCAPnL Address
n=0-4
CCAP0L=0EAH
CCAP1L=0EBH
CCAP2L=0ECH
CCAP3L=0EDH
CCAP4L=0EEH
7
6
5
4
3
2
1
0
Reset value
0
0
0
0
0
0
0
0
Table 6-10. CH: PCA Counter High
CH
Address 0F9H
7
6
5
4
3
2
1
0
Reset value
0
0
0
0
0
0
0
0
Table 6-11. CL: PCA Counter Low
CL
Address 0E9H
7
6
5
4
3
2
1
0
Reset value
0
0
0
0
0
0
0
0
6.3.1
PCA Capture Mode
To use one of the PCA modules in the capture mode either one or both of the CCAPM bits
CAPN and CAPP for that module must be set. The external CEX input for the module (on port 1)
is sampled for a transition. When a valid transition occurs the PCA hardware loads the value of
the PCA counter registers (CH and CL) into the module's capture registers (CCAPnL and
CCAPnH). If the CCFn bit for the module in the CCON SFR and the ECCFn bit in the CCAPMn
SFR are set then an interrupt will be generated (Refer to Figure 6-6).
29
4188F–8051–01/08
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