em78p156n ELAN Microelectronics Corp, em78p156n Datasheet - Page 33

• Manufacturer Part Number: em78p156n
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

Each instruction in the instruction set is a 13-bit word divided into an OP code and one or more operands.
Normally, all instructions are executed within one single instruction cycle (one instruction consists of 2
oscillator periods), unless the program counter is changed by instruction "MOV R2,A", "ADD R2,A", or by
instructions of arithmetic or logic operation on R2 (e.g. "SUB R2,A", "BS(C) R2,6", "CLR R2",
the execution takes two instruction cycles.
If for some reasons, the specification of the instruction cycle is not suitable for certain applications, try
modifying the instruction as follows:
Case (A) is selected by the CODE Option bit, called CLK. One instruction cycle consists of two oscillator clocks
if CLK is low, and four oscillator clocks if CLK is high.
Note that once the 4 oscillator periods within one instruction cycle is selected as in Case (A), the internal clock
source to TCC should be CLK=Fosc/4, instead of Fosc/ 2 as indicated in Fig. 5.
In addition, the instruction set has the following features:
This specification is subject to change without prior notice.
4.12 Instruction Set
(A) Change one instruction cycle to consist of 4 oscillator periods.
(B) "JMP", "CALL", "RET", "RETL", "RETI", or the conditional skip ("JBS", "JBC", "JZ", "JZA", "DJZ",
(1) Every bit of any register can be set, cleared, or tested directly.
"DJZA") commands which were tested to be true, are executed within two instruction cycles.
The instructions that are written to the program counter also take two instruction cycles.
Fig. 16 Circuit 2 for the Residue Voltage Protection
EM78P156N
/ RESET
Vdd
33
40K
Q1
R1
R2
EM78P156N
Vdd
OTP ROM
07.29.2004 (V1.2)
). In this case,