EM78P157N Datasheet, PDF (13/56 Pages) ELAN Microelectronics Corp – 8-Bit Microcontroller with OTP ROM

PC (A9 ~ A0)
EM78P157N
8-Bit Microcontroller with OTP ROM
Reset Vector
Interrupt Vector
000H
008H
Stack Level 1
Stack Level 2
Stack Level 3
Stack Level 4
Stack Level 5
On-chip Program
Memory
3FFH
Fig. 4-2 R2 (Program Counter) & Stack Organization
4.1.4 Status (R3) Register
Bit 7
GP2
Bit 6
GP1
Bit 5
GP0
Bit 4
T
Bit 3
P
Bit 2
Z
Bit 1
DC
Bit 0
C
Bit 0 (C): Carry flag
Bit 1 (DC): Auxiliary carry flag
Bit 2 (Z): Zero flag
Set to "1" if the result of an arithmetic or logic operation is zero
Bit 3 (P):
Power down bit
Set to “1” during power on or by a "WDTC" command
Reset to “0” by a "SLEP" command
Bit 4 (T):
Time-out bit
Set to “1” with the "SLEP" and "WDTC" commands, or during power up
Reset to “0” by WDT time-out
Bit 5~7 (GP0 ~ 2): General-purpose read/write bits
4.1.5 RAM Select (R4) Register
Bit 7
Bit 6
Not used (read only)
Bit 5
Bit 4
Bit 3
Bit 2
Select Registers
Bit 1
Bit 0
Z flag of R3 will set to “1” when R4 content is equal to “3F.” When R4=R4+1, R4
content will function as R0. See the data memory configuration shown in Section 4.1.
Bits 0~5: are used to select registers (Address: 00~06, 0F~3F) in indirect address
mode
Bits 6~7: are not used (read only)
Bits 6~7 are set to “1” all the time
Product Specification (V1.0) 09.22.2005
•7
(This specification is subject to change without further notice)