EM78P312N
8-Bit Microcontroller
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. Set to "1" if the result of an arithmetic or logic operation is zero.
Bit 1 (DC) : Auxiliary carry flag
Bit 0 (C) : Carry flag
R4 (RAM Select Register)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
GRBS1
RBS0
RSR5
RSR4
RSR3
RSR2
RSR1
RSR0
Bit 7: 6 ( GRBS1: GRBS0 ): determine which general purpose banks are activated
among the two banks. Use BANK instruction (e.g. BABK 1) to change bank.
GRBS1
GRBS0
General Purpose Register Bank (Address 20H ~ 3FH)
0
0
0
1
Bank 0
Bank 1
Bit 5: 0 ( RSR5 : RSR0 ): used to select the registers (Address: 00h~3Fh) in indirect
addressing mode. If no indirect addressing is used, the RSR can be used as
an 8-bit general-purpose read/write register. See the data memory
configuration in Fig. 5-2.
R5 (System Control Register)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
PS1
PS0
0
1
SIS
REM
Bits 5~4 (PS1~PS0): ROM Page select bits. User can use PAGE instruction (e.g.
PAGE 1) or set PS1~PS0 bits to change the ROM page. When executing a
"JMP", "CALL", or other instructions which cause the program counter to
change (e.g. MOV R2, A), PS1~PS0 are loaded into the 12th to11th bits of the
program counter and select one of the available program memory pages. Note
that RET (RETL, RETI) instruction does not change the PS1~PS0 bits. That
is, return will always be to the page from where the subroutine was called,
regardless of the PS1~PS0 bits current setting.
PS1
0
PS0
Program Memory Page [Address]
Page 0 [0000~03FF]
0
1
0
1
0
Page 1 [0400~07FF]
1
Page 2 [0800~0BFF]
1
Page 3 [0C00~0FFF]
Bit 1 ( SIS ) : Sleep and Idle mode select
SIS = “0” : Idle mode
SIS = “1” : Sleep mode
Bit 0 ( REM ) : Release method for sleep mode
REM = “0” : /SLEEP pin input rising edge released
REM = “1” : /SLEEP pin input “H” level released
Product Specification (V1.0) 10.03.2006
(This specification is subject to change without further notice)
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ELAN [ ELAN MICROELECTRONICS CORP ]
