Reset Source Hold Circuit; Figure 3.12-1 Block Diagram Of Reset Source Hold Circuit - Fujitsu MB91F109 FR30 Hardware Manual

3.12 Reset Source Hold Circuit

The reset source hold circuit holds the source of previous resetting. Reading the
circuit clears all flags to 0. Once a source flag is set, it is not cleared unless the circuit
is read.
Block Diagram of Reset Source Hold Circuit
Figure 3.12.1 is a block diagram of the reset source hold circuit.
From power-on cell
Setting for Reset Source Holding
No special settings are required to use the reset source hold function. Provide an instruction to
read the reset source register and an instruction to branch to the appropriate program, at the
beginning of the program to be placed at the reset entry address.

Figure 3.12-1 Block Diagram of Reset Source Hold Circuit

Internal bus
RSTX pin
RSTX
input circuit
PONR PONR
WDOG WDOG
ERST ERST
SRST SRST
clr
SRST
State = RST
STCR
3.12 Reset Source Hold Circuit
Initialized
by reading
Decoder
State
transi-
tion
.or.
circuit
101