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R01UH0336EJ0102 Rev.1.02
Page 328 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 9 Safety Functions
(10)
LRAMSTBYCTL – On-Chip RAM Resumption–Standby Control Register
This register prohibits access to and protects the on-chip RAM. This register
can be set so that the data in on-chip RAM are retained after a reset.
This register is initialized when the power supply is turned on or the power
supply voltage for the internal regulator (VDD) falls below the detection voltage
indicated for the POF.
Access
This register can be read/written in 8-bit units.
Address
FF83 F080
H
Initial value
00
H
Caution
Write to the register while access to the on-chip RAM is not in progress.
Operation is not guaranteed when a changeover is attempted during access to
the on-chip RAM. This register is initialized when the power supply is turned on
or the power supply voltage for the internal regulator (VDD) falls below the
detection voltage indicated for the POF. Therefore, if the LRAMSTBYCTL0 bit
is set to 1, the state of the on-chip RAM is retained after release from the reset
state. Change to normal mode before access to the on-chip RAM.
This function does not support data retention if the voltage goes out of the
guaranteed range.
Executing self-diagnosis (BIST) leads to the execution of memory BIST
regardless of the setting of the LRAMSTBYCTL register. In such cases, the
values in on-chip RAM are not guaranteed.
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
LRAM
STBYCTL0
R
R
R
R
R
R
R
R/W
Table 9-18
Contents of the LRAMSTBYCTL Register
Bit Position
Bit Name
Function
0
LRAMSTBYCTL0
Enables/disables access to the on-chip RAM
0: The on-chip RAM operates normally.
1: Access to the on-chip RAM is disabled (RAM is protected).