Toshiba H1 Series - Manual (Page 36)

TMP92CZ26A
92CZ26A-33
(4) Runaway provision with SFR protection register
(Purpose)
Provision in runaway of program by noise mixing.
Write operation to specified SFR is prohibited so that provision program in runaway
prevents that it is in the state which is fetch impossibility by stopping of clock,
memory control register (Memory controller, MMU) is changed.
And error handling in runaway becomes easy by INTP0 interruption.
Specified SFR list
1. Memory controller
B0CSL/H, B1CSL/H, B2CSL/H, B3CSL/H, BECSL/H
MSAR0, MSAR1, MSAR2, MSAR3,
MAMR0, MAMR1, MAMR2, MAMR3, PMEMCR,
MEMCR0, CSTMGCR, WRTMGCR, RDTMGCR0
RDTMGCR1, BROMCR
2. MMU
LOCALPX/PY/PZ, LOCALLX/LY/LZ,
LOCALRX/RY/RZ, LOCALWX/WY/WZ,
LOCALESX/ESY/ESZ, LOCALEDX/EDY/EDZ,
LOCALOSX/OSY/OSZ, LOCALODX/ODY/ODZ
3. Clock gear
SYSCR0, SYSCR1, SYSCR2, EMCCR0
4. PLL
PLLCR0,PLLCR1
5. PMC
PMCCTL
(Operation explanation)
Execute and release of protection (write operation to specified SFR) becomes
possible by setting up a double key to EMCCR1 and EMCCR2 register.
(Double key)
1
st -KEY: Succession writes in 5AH at EMCCR1 and A5H at EMCCR2
2 nd -KEY: Succession writes in A5H at EMCCR1 and 5AH at EMCCR2
A state of protection can be confirmed by reading EMCCR0<PROTECT>.
By reset, protection becomes OFF.
And INTP0 interruption occurs when write operation to specified SFR was executed
with protection on state.