t6020m ATMEL Corporation, t6020m Datasheet - Page 7

• Manufacturer Part Number: t6020m
• Description: Low-current Microcontroller For Watchdog Function
• Manufacturer: ATMEL Corporation

2.2.3
The MARC4 controller has seven programmable
registers and one condition code register. They are shown
in the following programming model.
Program Counter (PC)
The program counter (PC) is a 12-bit register which
contains the address of the next instruction to be fetched
Rev. A3, 02-Apr-01
Registers
PC
SP
RP
X
Y
FCh
11
04h
00h
Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Ï Ï Ï Ï
Ï Ï Ï Ï Ï Ï Ï
Ï Ï Ï Ï
Ï Ï Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï
Autosleep
RP
SP
X
Y
TOS–1
(192 x 4-bit)
RAM
7
7
7
7
Ï Ï Ï
Ï Ï Ï
TOS
CCR
Figure 6. Programming model
FFh
07h
03h
Expression
stack
C
Figure 5. RAM map
3
3
Return
stack
–– B
Global
variables
v
Global
variables
0
from the ROM. Instructions currently being executed are
decoded in the instruction decoder to determine the
internal micro-operations. For linear code (no calls or
branches) the program counter is incremented with every
instruction cycle. If a branch-, call-, return-instruction or
an interrupt is executed, the program counter is loaded
with a new address. The program counter is also used with
the TABLE instruction to fetch 8-bit wide ROM
constants.
I
0
0
0
0
0
0
0
0
Ï Ï Ï Ï Ï Ï
Ï Ï Ï Ï Ï Ï
Expression stack
11
Ï Ï Ï
Ï Ï Ï
Program counter
Return stack pointer
Expression stack pointer
RAM address register (Y)
Top of stack register
Condition code register
Interrupt enable
Branch
Reserved
Carry / borrow
RAM address register (X)
Return stack
3
TOS–1
TOS–2
4-bit
TOS
12-bit
0
SP
0
RP
T6020M
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