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PXD20RM Datasheet, PDF (731/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller
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EDSEL = 0
EDPOL = 1
Update to A1 A1 match
A1 match
A1 match
output flip-flop
selected counter bus
0x000500
0x001000
0x001100
0x001000
0x001100
0x001000
FLAG pin/register
A1 value1 0xxxxxxx 0x001000
0x001000
0x001000
0x001000
Notes: 1. CADR[n] = A2
A2 = A1 according to OU[n] bit
Figure 18-19. SAOC example with EDPOL value being transferred to the output flip-flop
EDSEL = 1
EDPOL = x
Update to A1 A1 match
A1 match
output flip-flop
selected counter bus
0x000500
0x001000
0x001100
0x001000
0x001100
FLAG pin/register
A1 value1 0xxxxxxx 0x001000 0x001000
0x001000
Notes: 1. CADR[n] = A2
A2 = A1 according to OU[n] bit
Figure 18-20. SAOC example toggling the output flip-flop
A1 match
0x001000
0x001000
EDSEL = 1
EDPOL = x
output flip-flop
selected counter bus
0x0
0x1
0x2
0x0
0x1
0x2
0x0
0x1
0x2
System Clock
A1 match
FLAG set event
FLAG pin/register
FLAG clear
A2 value1 0x1
Note: 1. CADR[n] <= A2
18.7.1.1.4 Modulus Counter Buffered (MCB) Mode
The MCB mode provides a time base which can be shared with other channels through the internal counter
buses. Register A1 is double buffered thus allowing smooth transitions between cycles when changing A2
register value on the fly. A1 register is updated at the cycle boundary, which is defined as when the internal
counter transitions to 0x1.
The internal counter values operates within a range from 0x1 up to register A1 value. If when entering
MCB mode coming out from GPIO mode the internal counter value is not within that range then the A
match will not occur causing the channel internal counter to wrap at the maximum counter value which is
0xff_ffff for a 24-bit counter. After the counter wrap occurs it returns to 0x1 and resume normal MCB
mode operation. Thus in order to avoid the counter wrap condition make sure its value is within the 0x1
to A1 register value range when the MCB mode is entered.
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
18-29
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