Philips 8-bit microcontroller with two-clock 80C51 core UM10109 Manual Do Utilizador
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 02 — 23 May 2005
51 of 133
Philips Semiconductors
UM10109
P89LPC932A1 User manual
in basic timer mode. In basic timer mode, writing a one to TCOU2 will cause the values to
be latched immediately and the value of TCOU2 will always read as zero. In PWM mode,
writing a one to TCOU2 will cause the contents of the shadow registers to be updated on
the next CCU Timer overflow. As long as the latch is pending, TCOU2 will read as one and
will return to zero when the latch takes place. TCOU2 also controls the latching of all the
Output Compare registers as well as the Timer Overflow Reload registers - TOR2.
be latched immediately and the value of TCOU2 will always read as zero. In PWM mode,
writing a one to TCOU2 will cause the contents of the shadow registers to be updated on
the next CCU Timer overflow. As long as the latch is pending, TCOU2 will read as one and
will return to zero when the latch takes place. TCOU2 also controls the latching of all the
Output Compare registers as well as the Timer Overflow Reload registers - TOR2.
9.5 Input capture
Input capture is always enabled. Each time a capture event occurs on one of the two input
capture pins, the contents of the timer is transferred to the corresponding 16-bit input
capture register ICRAH:ICRAL or ICRBH:ICRBL. The capture event is defined by the
Input Capture Edge Select – ICESx bit (x being A or B) in the CCCRx register. The user
will have to configure the associated I/O pin as an input in order for an external event to
trigger a capture.
capture pins, the contents of the timer is transferred to the corresponding 16-bit input
capture register ICRAH:ICRAL or ICRBH:ICRBL. The capture event is defined by the
Input Capture Edge Select – ICESx bit (x being A or B) in the CCCRx register. The user
will have to configure the associated I/O pin as an input in order for an external event to
trigger a capture.
A simple noise filter can be enabled on the input capture input. When the Input Capture
Noise Filter ICNFx bit is set, the capture logic needs to see four consecutive samples of
the same value in order to recognize an edge as a capture event. The inputs are sampled
every two CCLK periods regardless of the speed of the timer.
Noise Filter ICNFx bit is set, the capture logic needs to see four consecutive samples of
the same value in order to recognize an edge as a capture event. The inputs are sampled
every two CCLK periods regardless of the speed of the timer.
An event counter can be set to delay a capture by a number of capture events. The three
bits ICECx2, ICECx1 and ICECx0 in the CCCRx register determine the number of edges
the capture logic has to see before an input capture occurs.
bits ICECx2, ICECx1 and ICECx0 in the CCCRx register determine the number of edges
the capture logic has to see before an input capture occurs.
When a capture event is detected, the Timer Input Capture x (x is A or B) Interrupt Flag –
TICF2x (TIFR2.1 or TIFR2.0) is set. If EA and the Timer Input Capture x Enable bit –
TICIE2x (TICR2.1 or TICR2.0) is set as well as the ECCU (IEN1.4) bit is set, the program
counter will be vectored to the corresponding interrupt. The interrupt flag must be cleared
manually by writing a logic 0 to it.
TICF2x (TIFR2.1 or TIFR2.0) is set. If EA and the Timer Input Capture x Enable bit –
TICIE2x (TICR2.1 or TICR2.0) is set as well as the ECCU (IEN1.4) bit is set, the program
counter will be vectored to the corresponding interrupt. The interrupt flag must be cleared
manually by writing a logic 0 to it.
When reading the input capture register, ICRxL must be read first. When ICRxL is read,
the contents of the capture register high byte are transferred to a shadow register. When
ICRxH is read, the contents of the shadow register are read instead. (If a read from ICRxL
is followed by another read from ICRxL without ICRxH being read in between, the new
value of the capture register high byte (from the last ICRxL read) will be in the shadow
register).
the contents of the capture register high byte are transferred to a shadow register. When
ICRxH is read, the contents of the shadow register are read instead. (If a read from ICRxL
is followed by another read from ICRxL without ICRxH being read in between, the new
value of the capture register high byte (from the last ICRxL read) will be in the shadow
register).
Table 36:
Event delay counter for input capture
ICECx2
ICECx1
ICECx0
Delay (numbers of edges)
0
0
0
0
0
0
1
1
0
1
0
2
0
1
1
3
1
0
0
4
1
0
1
5
1
1
0
7
1
1
1
15