System Interface Unit (SIU)
MPC5553/MPC5554 Microcontroller Reference Manual,
Rev. 5
6-102
Freescale Semiconductor
6.3.1.19
External Clock Control Register (SIU_ECCR)
The SIU_ECCR controls the timing relationship between the system clock and the external clocks
ENGCLK and CLKOUT. All bits and fields in the SIU_ECCR are read/write and are reset by the
synchronous reset signal.
Address: Base + 0x0984
Access: Read / write[18:23, 28, 30:31]
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Address: Base + 0x0984
Access: Read / write[18:23, 28, 30:31]
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
0
0
ENGDIV
0
0
0
0
EBTS
0
EBDF
W
Reset
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
Figure 6-136. External Clock Control Register (SIU_ECCR)
Table 6-52. SIU_ECCR Field Descriptions
Name
Description
0–17
Reserved.
18–23
ENGDIV
[0:5]
Engineering clock division factor. Specifies the frequency ratio between the system clock
and ENGCLK. The ENGCLK frequency is divided by the system clock frequency according
to the equation:
Note: Clearing ENGDIV to 0 is reserved. Synchronization between ENGCLK and
CLKOUT cannot be guaranteed.
24–27
Reserved.
28
EBTS
External bus tap select. Changes the phase relationship between the system clock and
CLKOUT. Changing the phase relationship so that CLKOUT is advanced in relation to the
system clock increases the output hold time of the external bus signals to a non-zero value.
It also increases the output delay times, increases the input hold times to non-zero values,
and decreases the input setup times. Refer to the Electrical Specifications for how the
EBTS bit affects the external bus timing.
0 External bus signals have zero output hold times.
1 External bus signals have non-zero output hold times.
Note: The EBTS bit must not be modified while an external bus transaction is in progress.
Engineering clock frequency
System clock frequency
ENGDIV
2
---------------------------------------------------------------
=
Summary of Contents for MPC5553
Page 5: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 2 Freescale Semiconductor...
Page 21: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 xvi Freescale Semiconductor...
Page 47: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 1 26 Freescale Semiconductor...
Page 163: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 4 20 Freescale Semiconductor...
Page 179: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 5 16 Freescale Semiconductor...
Page 561: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 13 38 Freescale Semiconductor...
Page 615: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 14 54 Freescale Semiconductor...
Page 707: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 17 68 Freescale Semiconductor...
Page 755: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 18 48 Freescale Semiconductor...
Page 873: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 19 118 Freescale Semiconductor...
Page 984: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 Freescale Semiconductor 21 41...
Page 985: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 21 42 Freescale Semiconductor...
Page 1019: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 22 34 Freescale Semiconductor...
Page 1129: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 25 90 Freescale Semiconductor...
