PIC16C74B-20I/L Microchip Technology Inc., PIC16C74B-20I/L Datasheet - Page 27

• Manufacturer Part Number: PIC16C74B-20I/L
• Description: 44 PIN, 7 KB OTP, 192 RAM, 33 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16C74B-20I/L

• A/d Inputs: 8-Channel, 8-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 33
• Interface: I2C/SPI/USART
• Memory Type: OTP
• Number Of Bits: 8
• Package Type: 44-pin PLCC
• Programmable Memory: 7K Bytes
• Ram Size: 192 Bytes
• Speed: 4 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2.5-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

4.5
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF reg-
ister. Any instruction using the INDF register actually
accesses the register pointed to by the File Select Reg-
ister, FSR. Reading the INDF register itself indirectly
(FSR = ’0’) will read 00h. Writing to the INDF register
indirectly results in a no-operation (although status bits
may be affected). An effective 9-bit address is obtained
by concatenating the 8-bit FSR register and the IRP bit
(STATUS<7>), as shown in Figure 4-4.
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 4-2.
FIGURE 4-4:
Note 1: For register file map detail, see Figure 4-2.
2000 Microchip Technology Inc.
RP1:RP0
bank select
0
2: Shaded portions are not implemented; maintain the IRP and RP1 bits clear.
Indirect Addressing, INDF and
FSR Registers
location select
6
Direct Addressing
Data
Memory
DIRECT/INDIRECT ADDRESSING
from opcode
00h
7Fh
Bank 0
00
0
80h
FFh
Bank 1
01
PIC16C63A/65B/73B/74B
100h
17Fh
Bank 2
10
not used
EXAMPLE 4-2:
NEXT
CONTINUE
Note:
180h
1FFh
Bank 3
11
Maintain the IRP and RP1 bits clear.
IRP
movlw
movwf
clrf
incf
btfss
goto
:
0
bank select
7
0x20
FSR
INDF
FSR,F
FSR,4
NEXT
Indirect Addressing
INDIRECT ADDRESSING
;initialize pointer
;to RAM
;clear INDF register
;inc pointer
;all done?
;no clear next
;yes continue
FSR register
DS30605C-page 27
location select
0