MC68HC705C9A_1 Datasheet, PDF (55/157 Pages) Freescale Semiconductor, Inc – General Release Specification

Freescale Semiconductor, Inc.
General Release Specification
MC68HC05C9A Compatible COP
5.6.1 C9A COP Reset Register
This write-only register, shown in Figure 5-4, is used to reset the COP.
$001D Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write: Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 5-4. COP Reset Register (COPRST)
The sequence required to reset the COP timer is as follows:
• Write $55 to the COP reset register
• Write $AA to the COP reset register
Both write operations must occur in the order listed, but any number of
instructions may be executed between the two write operations provided
that the COP does not time out between the two writes. The elapsed
time between software resets must not be greater than the COP timeout
period. If the COP should time out, a system reset will occur and the
device will be re-initialized in the same fashion as a power-on reset or
reset.
Reading this register does not return valid data.
MC68HC705C9A — Rev. 2.0
Resets
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