EM78M612
Universal Serial Bus Microcontroller Series
8.2.1.1 Operation Registers in Bank 0
The following introduces each of the Operation Registers under the Special Purpose
Registers in Bank 0. These Operation Registers are arranged according to the order of
registers’ address. Note that some registers are read only, while others are both readable
and writable.
R0 (Indirect Address Register) Default Value: (0B_0000_0000)
R0 is not a physically implemented register. Its major function is to be an indirect address
pointer. Any instruction using R0 as a pointer actually accesses the data pointed by the RAM
Select Register (R4).
R1 (Time / Clock Counter) Default Value: (0B_0000_0000)
This register TCC, is an 8-bit timer or counter. It is readable and writable as any other
register.
After Power-on reset and WatchDog reset, the initial value of this register is 0x00.
R2 (Program Counter & Stack) Default Value: (0B_0000_0000)
The EM78M612 Program Counter is an 11-bit long register that allows access to 2K bytes of
Program Memory. The Program Counter is cleared after Power-on reset or WatchDog reset.
The first instruction that is executed after a reset is located at Address 00h.
CALL
Stack 1
Stack 2
Stack 3
Stack 4
Stack 5
RET
RETL
RETI
Reset Vector
0x0000
0x0001
0x000A
Interrupt Vector
USB Interrupt Vector
Page 0
Page 1
0x03FF
0x0400
0x07FF
This specification may change without further notice.
2004/4/28 V1.1
10
ELAN [ ELAN MICROELECTRONICS CORP ]
