ML51/ML54/ML56
Sep. 01, 2020
Page
320
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Rev 2.00
ML
51
/ML
54
/ML
5
6 S
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TECHNI
CA
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RE
F
E
R
E
NC
E
M
A
NU
A
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ML51/M
L54
/M
L56
Series
Tec
hnical Reference
Manual
CHPCON
– Chip Control (TA Protected)
Register
SFR Address
Reset Value
CHPCON
9FH, Page 0, TA protected
Software 0000_00U0 b
Others 0000_00C0 b
7
6
5
4
3
2
1
0
SWRST
IAPFF
-
-
-
-
BS
[1]
IAPEN
W
R/W
-
-
-
-
R/W
R/W
Address: 9FH, Page 0
Reset value: Software: 0000 00U0b / others: 0000 00C0b
Bit
Name
Description
[1]
BS
Boot Select
This bit defines from which block that MCU re-boots after all resets.
0 = MCU will re-boot from APROM after all resets.
1 = MCU will re-boot from LDROM after all resets.
[1]
BS is initialized by being loaded from the inverted value of CBS bit in CONFIG0.7 after resets except software
reset. It keeps unchanged after software reset.
After the MCU is released from reset state, the hardware will always check the BS bit instead of
the CBS bit to determine from which block that the device reboots.
Reset State
6.2.3.7
The reset state besides power-on reset does not affect the on-chip RAM. The data in the RAM will be
preserved during the reset. After the power-on reset the RAM contents will be indeterminate.
After a reset, most of SFR go to their initial values except bits, which are affected by different reset
events.. The Program Counter is forced to 0000H and held as long as the reset condition is applied.
Note that the Stack Pointer is also reset to 07H and thus the stack contents may be effectively lost
during the reset event even though the RAM contents are not altered.
After a reset, all peripherals and interrupts are disabled. The I/O port latches resumes FFH and I/O
mode input-only.