EM78468AQ EMC [ELAN Microelectronics Corp], EM78468AQ Datasheet - Page 16

• Manufacturer Part Number: EM78468AQ
• Description: 8-BIT Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

EM78468
8-BIT Microcontroller
12 •
4.1.4 R3/SR (Status Register)
4.1.5
Bit 7: Not used
Bit 6, 5 (PS1 ~ PS0): Page select bits
PS0~PS1 are used to select a ROM page. User can use PAGE instruction (e.g. PAGE 1)
or set PS1~PS0 bits to change ROM page. When executing a "JMP", "CALL", or other
instructions which causes the program counter to be changed (e.g. MOV R2, A),
PS0~PS1 are loaded into the 11th and 12th bits of the program counter where it selects
one of the available program memory pages. Note that RET (RETL, RETI) instruction
does not change the PS0~PS1 bits. That is, the return will always be to the page from
where the subroutine was called, regardless of the current setting of PS0~PS1 bits.
Bit 4 (T): Time-out bit. Set to 1 by the "SLEP" and "WDTC" commands or during power
up and reset to 0 by WDT timeout.
WDT wake up from sleep mode
WDT time out (not sleep mode)
/RESET wake up from sleep
Power up
Low pulse on /RESET
Bit 3 (P): Power down bit. Set to 1 during power on or by a "WDTC" command and reset
to 0 by a "SLEP" command.
Bit 2 (Z): Zero flag
Bit 1 (DC): Auxiliary carry flag.
Bit 0 (C): Carry flag
Bits 7 ~ 6 (RBS1 ~ RBS0) determine which bank is activated among the 4 banks. See
the configuration of the data memory in Fig.4. Use BANK instruction (e.g. BABK 1) to
change bank.
RBS1
Bit 7
Bit 7
--
(Address: 03h)
PS1
R4/RSR (RAM Select Register)
(Address: 04h)
0
0
1
1
RBS0
Bit 6
Bit 6
EVENT
PS1
PS0
0
1
0
1
RSR5
Bit 5
Bit 5
PS0
RSR4
Bit 4
Bit 4
Page 3 (C00H ~ FFFH)
Page 2 (800H ~ BFFH)
Page 0 (000H ~ 3FFH)
Page 1 (400H ~ 7FFH)
ROM Page (Address)
(This specification is subject to change without further notice)
T
T
0
0
1
1
1
RSR3
Bit 3
Bit 3
Product Specification (V1.1) 04.11.2005
P
P
1
0
1
0
1
RSR2
Bit 2
Bit 2
Z
X: don't care
REMARK
RSR1
Bit 1
Bit 1
DC
RSR0
Bit 0
Bit 0
C