MPC555
/
MPC556
TIME PROCESSOR UNIT 3
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
17-8
solve down to the TPU3 IMB clock divided by eight.
illustrates the TCR2
pre-divider and pre-scaler control.
Figure 17-4 TCR2 Prescaler Control
is a summary of prescaler output (assuming a divide-by-one value for the
pre-divider prescaler.
17.4 Programming Model
The TPU3 memory map contains three groups of registers:
• System configuration registers
• Channel control and status registers
• Development support and test verification registers
All registers except the channel interrupt status register (CISR) must be read or written
by means of half-word (16-bit) or word (32-bit) accesses. The address space of the
TPU3 memory map occupies 512 bytes. Unused registers within the 512-byte address
space return zeros when read.
shows the TPU3 address map.
Table 17-4 TCR2 Prescaler Control
TCR2 Value
Internal Clock Divide Ratio
External Clock Divide Ratio
TCR2PSCK2 = 0
TCR2PSCK2 = 1
TCR2PSCK2 = 0
TCR2PSCK2 = 1
0b00
8
8
1
1
0b01
16
24
2
3
0b10
32
56
4
7
0b11
64
120
8
15
TCR2
PRESCALER
TCR2
1,2,4,8
TCR2PSCK2
Pre-divider
Clock
Source
MUX
Control
TCR2
Pin
CLOCK
DIV8
Prescaler
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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