PIC17C756A-33/L Microchip Technology Inc., PIC17C756A-33/L Datasheet - Page 55

• Manufacturer Part Number: PIC17C756A-33/L
• Description: 68 PIN, 32 KB OTP, 902 RAM, 50 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC17C756A-33/L

• A/d Inputs: 12-Channel, 10-Bit
• Cpu Speed: 8.25 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 52
• Interface: I2C/SPI/USART
• Memory Type: OTP
• Number Of Bits: 8
• Package Type: 68-pin PLCC
• Programmable Memory: 32K Bytes
• Ram Size: 902 Bytes
• Speed: 16 MHz
• Timers: 2-8-bit, 2-16-bit
• Voltage, Range: 3-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part

7.4.2
The indirect addressing capability has been enhanced
over that of the PIC16CXX family. There are two control
bits associated with each FSR register. These two bits
configure the FSR register to:
• Auto-decrement the value (address) in the FSR
• Auto-increment the value (address) in the FSR
• No change to the value (address) in the FSR after
These control bits are located in the ALUSTA register.
The FSR1 register is controlled by the FS3:FS2 bits
and FSR0 is controlled by the FS1:FS0 bits.
When using the auto-increment or auto-decrement fea-
tures, the effect on the FSR is not reflected in the
ALUSTA register. For example, if the indirect address
causes the FSR to equal '0', the Z bit will not be set.
If the FSR register contains a value of 0h, an indirect
read will read 0h (Zero bit is set) while an indirect write
will be equivalent to a NOP (status bits are not affected).
Indirect addressing allows single cycle data transfers
within the entire data space. This is possible with the
use of the MOVPF and MOVFP instructions, where either
'p' or 'f' is specified as INDF0 (or INDF1).
If the source or destination of the indirect address is in
banked memory, the location accessed will be deter-
mined by the value in the BSR.
A simple program to clear RAM from 20h - FFh is
shown in Example 7-1.
EXAMPLE 7-1:
LP
after an indirect access
after an indirect access
an indirect access
2000 Microchip Technology Inc.
MOVLW
MOVWF
BCF
BSF
BCF
MOVLW
CLRF
CPFSEQ FSR0
GOTO
:
:
INDIRECT ADDRESSING
OPERATION
0x20
FSR0
ALUSTA, FS1
ALUSTA, FS0
ALUSTA, C
END_RAM + 1
INDF0, F
LP
INDIRECT ADDRESSING
; FSR0 = END_RAM+1?
;
; FSR0 = 20h
; Increment FSR
; after access
; C = 0
;
; Addr(FSR) = 0
; NO, clear next
; YES, All RAM is
; cleared
7.5
File registers TBLPTRL and TBLPTRH form a 16-bit
pointer to address the 64K program memory space.
The table pointer is used by instructions TABLWT and
TABLRD.
The TABLRD and the TABLWT instructions allow trans-
fer of data between program and data space. The table
pointer serves as the 16-bit address of the data word
within the program memory. For a more complete
description of these registers and the operation of
Table Reads and Table Writes, see Section 8.0.
7.6
The table latch (TBLAT) is a 16-bit register, with
TBLATH and TBLATL referring to the high and low
bytes of the register. It is not mapped into data or pro-
gram memory. The table latch is used as a temporary
holding latch during data transfer between program
and data memory (see TABLRD, TABLWT, TLRD and
TLWT instruction descriptions). For a more complete
description of these registers and the operation of
Table Reads and Table Writes, see Section 8.0.
Table Pointer (TBLPTRL and
TBLPTRH)
Table Latch (TBLATH, TBLATL)
PIC17C7XX
DS30289B-page 55