Peripheral Pin Multiplexing (PPM) Module
MPC561/MPC563 Reference Manual, Rev. 1.2
18-24
Freescale Semiconductor
18.4.12
Scale Transmit Clock Register (SCALE_TCLK_REG)
SCALE_TCLK_REG is used to set the rate of the PPM_TCLK that provides the timing for data transfer
into and out of the PPM module. The PPM_TCLK frequency is derived from the system clock, F
SYSCLK
.
PPM_TCLK is software programmable using the following formula:
F
PPM_TCLK
= F
SYSCLK
/ (2 * SCT[6:0])
The range of PPM_TCLK frequencies available is:
Data transmitted
0x3034
0b 0011 0000 0011 0100
Example 3
SHORT_CH_REG
0x00FF
SHORT_CH[7:0] = 1, therefore bits (TX_DATA[1, 3, 5,
7, 9, 11, 13, 15] are enabled for re-transmission.
TX_DATA[0:15]
0x1234
0b 0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
Underlines show bits to be re-transmitted
Data transmitted
0x303C
0b 0011 0000 0011 1100
Table 18-12. SCALE_TCLK Frequencies
Minimum
Maximum
F
SYSCLK
/256
F
SYSCLK
/2
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
Field
RESERVED
SCT[6:0]
SRESET
0000_0000_0000_0000
Addr
0x30 5C2A
Figure 18-27. Scale Transmit Clock Register (SCALE_TCLK_REG)
Table 18-13. SCALE_TCLK_REG Bit Descriptions
Bits
Name
Description
0:8
—
Reserved
9:15
SCT[6:0]
Determines the frequency of PPM_TCLK.
• SCT[6:0] = 0 F
SYSCLK
/256
• SCT[6:0] = 1 to 127 F
SYSCLK
/ (2 * SCT[6:0])
Writing to SCT[6:0] while the PPM is enabled will cause an irregular PPM cycle to
occur.
Table 18-11. Examples of the SHORT_CH Bits (continued)
Register Name
Register
Contents
Comments
Summary of Contents for MPC561
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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...
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Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
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