AT89C51RB2/RC2
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 Mod-
ule (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
(see Figure 13).
Figure 13. PCA Capture Mode
CCON
CCF4 CCF3 CCF2 CCF1 CCF0
CF
CR
0xD8
PCA IT
PCA Counter/Timer
Cex. n
CH
CL
Capture
CCAPnH
CCAPnL
CCAPMn, n = 0 to 4
0xDA to 0xDE
ECOMnCAPPn CAPNn MATn TOGn PWMn ECCFn
39
4180E–8051–10/06
ATMEL [ ATMEL ]
