Modular Input/Output Subsystem (MIOS14)
MPC561/MPC563 Reference Manual, Rev. 1.2
17-36
Freescale Semiconductor
Figure 17-20. Single Shot Output Transition Example
17.9.3.5.3
Output Port Bit Operation
The output port bit operation is selected by leaving both channels disabled, (i.e., by writing to neither
register A nor B). The EDPOL bit alone controls the output value. The same result can be achieved by
keeping EDPOL at zero and using the FORCA and FORCB bits to obtain the desired output level.
17.9.3.6
Output Pulse Width Modulation (OPWM) Mode
OPWM mode is selected by setting MODE[0:3] to 1xxx. The MODE[1:3] bits allow some of the
comparator bits to be masked.
This mode allows pulse width modulated output waveforms to be generated, with eight selectable
frequencies. Frequencies are only relevant as such if the counter bus is driven by a counter as a time
reference. Both channels (A and B) are used to generate one PWM output signal on the MDASM signal.
Channel B is accessed via register B1. Register B2 is not accessible. Channels A and B define respectively
the leading and trailing edges of the PWM output pulse. The value in register B1 is transferred to register
B2 each time a match occurs on either channel A or B.
NOTE
A FORCA or FORCB does not cause a transfer from B1 to B2.
The value loaded in register A is compared with the value on the 16-bit counter bus each time the counter
bus is updated. When a match on A occurs, the FLAG line is activated and the output flip-flop is set. The
value loaded in register B2 is compared with the value on the 16-bit counter bus each time the counter bus
is updated. When a match occurs on B, the output flip-flop is reset.
F LAG reset
by software
Mode selection; MODE0 = 1
Output signal
FLAG bit
0x1000
0x1000
0xxxxx
0xxxxx
Register B1
Register B2
0xxxxx
0xxxxx
0x1000
0x1000
0xxxxx
0x1100
0xxxxx
0x1000
0x1100
0x1000
0x1100
0xxxxx
0x0500
0x1000
0x1100
0x1000
0x1100
0x1000
Register A
0xxxxx
0xxxxx
Internal Register, not accessible to software
A Event
B Event
Write to A
Write to B
FLAG reset
by software
Reoccurences of the timer count do
not trigger a response unless registers
A or B have been written again.
Counter Bus
16-bit
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...