Renesas RL78/G1P Hardware User Manual page 670

RL78/G1P
20.6 RAM guard function
In order to guarantee safety during operation, the IEC61508 standard mandates that important data stored in the RAM
be protected, even if the CPU freezes.
This RAM guard function is used to protect data in the specified memory space.
If the RAM guard function is specified, writing to the specified RAM space is disabled, but reading from the space can
be carried out as usual.
20.6.1 Invalid memory access detection control register (IAWCTL)
This register is used to control the detection of invalid memory access and RAM/SFR guard function.
GRAM1 and GRAM0 bits are used in RAM guard function.
The IAWCTL register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 20-9. Format of Invalid Memory Access Detection Control Register (IAWCTL)
Address: F0078H After reset: 00H
Symbol 7
IAWCTL IAWEN
GRAM1
0
0
1
1
R01UH0895EJ0100 Rev.1.00
Nov 29, 2019
R/W
6 5
0 GRAM1
GRAM0
0 Disabled. RAM can be written to.
1 The 128 bytes starting at the lower RAM address
0 The 256 bytes starting at the lower RAM address
1 The 512 bytes starting at the lower RAM address
CHAPTER 20 SAFETY FUNCTIONS
4 3
GRAM0 0
RAM guard space
2 1
GPORT GINT
0
GCSC
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