RL78/G1P
CHAPTER 17 RESET FUNCTION
R01UH0895EJ0100 Rev.1.00
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Nov 29, 2019
17.2 Register for Confirming Reset Source
17.2.1 Reset control flag register (RESF)
Many internal reset generation sources exist in the RL78/G1P. The reset control flag register (RESF) is used to store
which source has generated the reset request.
The RESF register can be read by an 8-bit memory manipulation instruction.
RESET input, reset by power-on-reset (POR) circuit, and reading the RESF register clear TRAP, WDTRF, RPERF,
IAWRF, and LVIRF flags.
Figure 17-4. Format of Reset Control Flag Register (RESF)
Address: FFFA8H After reset: 00H
Note 1
R
Symbol
7 6 5 4 3 2 1 0
RESF TRAP
0
0 WDTRF 0 RPERF
IAWRF LVIRF
TRAP
Internal reset request by execution of illegal instruction
Note 2
0
Internal reset request is not generated, or the RESF register is cleared.
1
Internal reset request is generated.
WDTRF
Internal reset request by watchdog timer (WDT)
0
Internal reset request is not generated, or the RESF register is cleared.
1
Internal reset request is generated.
RPERF
Internal reset request by RAM parity
0
Internal reset request is not generated, or the RESF register is cleared.
1
Internal reset request is generated.
IAWRF
Internal reset request by illegal-memory access
0
Internal reset request is not generated, or the RESF register is cleared.
1
Internal reset request is generated.
LVIRF
Internal reset request by voltage detector (LVD)
0
Internal reset request is not generated, or the RESF register is cleared.
1
Internal reset request is generated.
Notes 1.
The value after reset varies depending on the reset source. See
Table 17-3
.
2.
The illegal instruction is generated when instruction code FFH is executed.
Reset by the illegal instruction execution not issued by emulation with the in-circuit emulator or on-chip
debug emulator.
Cautions 1. Do not read data by a 1-bit memory manipulation instruction.
2.
When enabling RAM parity error resets (RPERDIS = 0), be sure to initialize the used RAM area at
data access or the used RAM area + 10 bytes at execution of instruction from the RAM area.
Reset generation enables RAM parity error resets (RPERDIS = 0). For details, see 20.5 RAM
parity error detection function.