PXD20RM Datasheet, PDF (730/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

EDSEL = 1
EDPOL = x
Edge detect
Edge detect
Edge detect
input signal¹
selected counter bus 0x001000 0x001001 0x001102 0x001103 0x001104 0x001105 0x001106 0x001107 0x001108
FLAG set event
FLAG pin/register
FLAG clear
A2 (captured) value² 0xxxxxxx 0x001000
0x001103
0x001108
Notes: 1. After input filter
2. CADR[n] <= A2
Figure 18-18. Single Action Input Capture with both edges triggering example
18.7.1.1.3 Single Action Output Compare (SAOC) Mode
In SAOC mode (MODE[0:6]=0000011) a match value is loaded in register A2 and then immediately
transferred to register A1 to be compared with the selected time base. When a match occurs, the EDSEL
bit selects whether the output flip-flop is toggled or the value in EDPOL is transferred to it. Along with
the match the FLAG bit is set to indicate that the output compare match has occurred. Writing to CADR[n]
stores the value in register A2 and reading to CADR[n] returns the value of register A1.
An output compare match can be simulated in software by setting the FORCMA bit in CCR[n]. In this
case, the FLAG bit is not set.
When SAOC mode is entered coming out from GPIO mode the output flip-flop is set to the complement
of the EDPOL bit in CCR[n].
Counter bus can be either internal or external and is selected through BSL[0:1] bits.
Figure 18-19 and Figure 18-20 show how the Unified Channel can be used to perform a single output
compare with EDPOL value being transferred to the output flip-flop and toggling the output flip-flop at
each match, respectively. Note that once in SAOC mode the matches are enabled thus the desired match
value on register A1 must be written before the mode is entered. A1 register can be updated at any time
thus modifying the match value which will reflect in the output signal generated by the channel.
Subsequent matches are enabled with no need of further writes to CADR[n]. The FLAG is set at the same
time a match occurs.
NOTE
The channel internal counter in SAOC mode is free-running. It starts
counting as soon as the SAOC mode is entered.
18-28
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor