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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Timer 2 with
Additional 4-channel PCA
Timer 2 with
Additional 4-channel PCA
Capture Modes
Timer 2 has two capture modes, the Capture on Edge Mode, known as Capture Mode 0, and the
Capture on Write Mode, known as Capture Mode 1. The required mode is selected using the
COCAHn and COCALn bits in the CCEN register. The accompanying diagram illustrates the basic
operational blocks.
CCn
CRCH
CRCL
TH�
TL�
I3FR bit
COCAHn
COCALn
11
01
W�ite to CCLn(CRCL)
Capt��e Mode 1
Capt��e Mode 0
Note:
1. n=0~3
�. CC1~CC3 capt��e inp�t b� �ising edge
3. CC0 capt��e inp�t b� �ising o� falling edge selected b� the I3FR bit
4. W�ite to CCLn is fo� CC1~CC3 and W�ite to CRCL is fo� CC0
Capture Modes Block Diagram
Capture On Edge Mode
To select this mode, bits COCAHn and COCALn in the CCEN register, should be set to “01”
respectively. In this mode, Modules 1~3 will capture the Timer 2 counter on the rising edge of an
external signal applied on the CC1~CC3 pins. Module 0 will capture the Timer 2 counter contents
on a rising or falling edge applied on the CC0 pin. The rising or falling edge trigger is controlled by
the I3FR bit in the T2CON register.
Capture On Write Mode
To select this mode, bits COCAHn and COCALn in the CCEN register, should be set to “11”
respectively. In this mode a Timer 2 Capture is generated by any write operation into the capture
register low byte. The value written to capture register is irrelevant for this function. The Timer 2
contents will be latched into the appropriate capture registers.