RL78/G1H CHAPTER 24 SAFETY FUNCTIONS
R01UH0575EJ0120 Rev. 1.20 Page 786 of 920
Dec 22, 2016
24.3.5 SFR guard function
In order to guarantee safety during operation, the IEC61508 standard mandates that important SFRs be
protected from being overwritten, even if the CPU freezes.
This SFR guard function is used to protect data in the control registers used by the port function, interrupt
function, clock control function, voltage detection function, and RAM parity error detection function.
If the SFR guard function is specified, writing to the specified SFRs is disabled, but reading from the SFRs can
be carried out as usual.
24.3.5.1 Invalid memory access detection control register (IAWCTL)
This register is used to control the detection of invalid memory access and RAM/SFR guard function.
GPORT, GINT and GCSC bits are used in SFR guard function.
The IAWCTL register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 24 - 10 Format of Invalid memory access detection control register (IAWCTL)
Note Pxx (Port register) is not guarded.
Address: F0078H After reset: 00H R/W
Symbol76543210
IAWCTL IAWEN 0 GRAM1 GRAM0 0 GPORT GINT GCSC
GPORT Control registers of port function guard
0 Disabled. Control registers of port function can be read or written to.
1
Enabled. Writing to control registers of port function is disabled. Reading is enabled.
[Guarded SFR] PMxx, PUxx, PIMxx, POMxx, PMCxx, ADPC, PIORx
Note
GINT Registers of interrupt function guard
0 Disabled. Registers of interrupt function can be read or written to.
1
Enabled. Writing to registers of interrupt function is disabled. Reading is enabled.
[Guarded SFR] IFxx, MKxx, PRxx, EGPx, EGNx
GCSC
Control registers of clock control function, voltage detector, and RAM parity error detection function guard
0
Disabled. Control registers of clock control function, voltage detector and RAM parity error detection
function can be read or written to.
1
Enabled. Writing to control registers of clock control function, voltage detector and RAM parity error
detection function is disabled. Reading is enabled.
[Guarded SFR] CMC, CSC, OSTS, CKC, PERx, OSMC, LVIM, LVIS, RPECTL
To Next Page
Loading...
Need help?
General
