BAT32G1x9 user manual | Chapter 32 Security features
1117 / 1149
Rev.1.02
32.3.3
RAM parity error detection function
The IEC60730 standard requires validation of RAM data. Therefore, the BAT32G139's RAM is appended
with 1 bit of parity bits for every 8 bits. The RAM parity error detection feature appends parity bits when writing
data, checks parity bits when reading data, and can generate resets when parity errors occur.
32.3.3.1
RAM Parity Error Control Register (RPECTL).
This register controls the error confirmation bit for parity and the reset due to parity error. The RPECTL
register is set via the 8-bit memory operation instruction. After generating a reset signal, the value of this
register changes to "00H".
Figure 32-7 Ram parity error control register (RPECTL) format
Address: 40020425H
after reset:
00HR/W
symbol
RPECTL
RPERDIS
Mask flag for parity error reset
0
Enable parity error reset to occur.
1
Parity error reset is prohibited.
RPEF
Parity error status flag
0
No parity errors occurred.
1
A parity error occurred.
Note Attach parity bits when writing data, and check parity bits when reading data.
Therefore, to allow ram parity error reset (RPERDIS=0) to be generated, the "RAM region used" must be
initialized when the data is accessed and before reading the data.
Because it is running on a pipeline, the CPU performs a read-ahead, and a RAM parity error may occur due to the
uninitialized RAM area before reading the RAM area used. Therefore, to allow for a RAM parity error reset
(RPERDIS=0), it is necessary to execute instructions from the RAM region to the "RAM region used." +10 bytes"
of the region is initialized.
Note 1
The initial state is to allow parity error reset (RPERDIS=0).
2. Even if set to disable parity error reset (RPERDIS=1), the RPEF flag is set to "1" when a parity error occurs. If the
RPEF bit is set to allow parity test error reset (RPERDIS=0) in the state where the RPEF bit is "1", the RPERDIS is
cleared to "0" A parity error is generated when reset.
3. Set the RPF flag of the RUBTL register to "1" due to a RAM parity error, and reset the source by writing "0" or
resetting all the sources Flag "0". When the RPF flag is "1", the RPEF flag remains in the "1" state even if the RAM
without parity error is read.
4. The scope of RAM parity detection does not include universal registers.
7
6
5
4
3
2
1
0
RPERDIS
0
0
0
0
0
0
RPEF