P12C508 Microchip Technology, P12C508 Datasheet - Page 13

• Manufacturer Part Number: P12C508
• Description: 8-Pin / 8-Bit CMOS Microcontroller
• Manufacturer: Microchip Technology

4.2.2
The Special Function Registers are registers used by
the CPU and peripheral functions to control the
operation of the device (Table 4-1).
TABLE 4-1:
Address
N/A
N/A
00h
01h
02h
03h
04h
04h
04h
05h
06h
Legend: Shaded boxes = unimplemented or unused, — = unimplemented, read as '0' (if applicable)
Note 1: The upper byte of the Program Counter is not directly accessible. See Section 4.5
1996 Microchip Technology Inc.
(1)
SPECIAL FUNCTION REGISTERS
x = unknown, u = unchanged, q = see the tables in Section 7.7 for possible values.
for an explanation of how to access these bits.
TRIS
OPTION
INDF
TMR0
PCL
STATUS
FSR
(12C508)
FSR
(12C509)
FSR
OSCCAL
GPIO
Name
SPECIAL FUNCTION REGISTER SUMMARY
I/O control registers
Contains control bits to configure Timer0, Timer0/WDT
prescaler, interrupt on change, and weak pull-ups
Uses contents of FSR to address data memory (not a physical
register)
8-bit real-time clock/counter
Low order 8 bits of PC
Indirect data memory address pointer
Indirect data memory address pointer
Indirect data memory address pointer
GPWUF
CAL7
Bit 7
—
CAL6
Bit 6
—
—
CAL5
Bit 5
GP5
PA0
Advance Information
CAL4
Bit 4
GP4
TO
Bit 3
GP3
PD
—
Bit 2
GP2
—
Z
The special registers can be classified into two sets.
The special function registers associated with the
“core” functions are described in this section. Those
related to the operation of the peripheral features are
described in the section for each peripheral feature.
Bit 1 Bit 0
GP1
DC
—
GP0
—
C
--11 1111
1111 1111
xxxx xxxx
xxxx xxxx
1111 1111
0001 1xxx
111x xxxx
110x xxxx
1xxx xxxx
0111 ----
--xx xxxx
Power-On
Value on
Reset
PIC12C5XX
WDT Reset
--11 1111
1111 1111
uuuu uuuu
uuuu uuuu
1111 1111
000q quuu
111u uuuu
11uu uuuu
1uuu uuuu
uuuu ----
--uu uuuu
MCLR and
Value on
DS40139A-page 13
Wake-up on
Pin Change
--11 1111
1111 1111
uuuu uuuu
uuuu uuuu
1111 1111
100q quuu
111u uuuu
11uu uuuu
1uuu uuuu
uuuu ----
--uu uuuu
Value on