EM78P156EL
OTP ROM
4. FUNCTION DESCRIPTION
OSCO
/RESET
OSCI
WDT timer
Oscillator/Timing
Control
TCC
/INT
Prescaler
IOCA
ROM
R2
Stack
RAM
Interrupt
Controller
Instruction
Register
R3
ALU
R4
R1(TCC)
Instruction
Decoder
ACC
DATA & CONTROL BUS
P60//INT
P61
P62
P63
P64
P65
P66
P67
IOC6
R6
I/O
PORT 6
IOC5
R5
I/O
PORT 5
P50
P51
P52
P53
Fig. 2 Function Block Diagram
4.1 Operational Registers
1. R0 (Indirect Addressing Register)
R0 is not a physically implemented register. Its major function is to perform as an indirect addressing
pointer. Any instruction using R0 as a pointer actually accesses data pointed by the RAM Select
Register (R4).
2. R1 (Time Clock /Counter)
• Increased by an external signal edge, which is defined by TE bit (CONT-4) through the TCC pin, or
by the instruction cycle clock.
• Writable and readable as any other registers.
• Defined by resetting PAB(CONT-3).
• The prescaler is assigned to TCC, if the PAB bit (CONT-3) is reset.
• The contents of the prescaler counter will be cleared only when TCC register is written with a value.
This specification is subject to change without prior notice.
8
07.29.2004 (V1.3)
EMC [ ELAN MICROELECTRONICS CORP ]
