PIC16C72A Microchip Technology, PIC16C72A Datasheet - Page 4

• Manufacturer Part Number: PIC16C72A
• Description: 28-Pin 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

READING PROGRAM MEMORY
The FLASH Program Memory is readable during nor-
mal operation over the entire V
addressed through Special Function Registers (SFR).
Up to 14-bit numbers can be stored in memory for use
as calibration parameters, serial numbers, packed 7-bit
ASCII, etc. Executing a program memory location con-
taining data that forms an invalid instruction results in
a NOP.
There are five SFRs used to read the program and
memory:
• PMCON1
• PMDATL
• PMDATH
• PMADRL
• PMADRH
The program memory allows word reads. Program
memory access allows for checksum calculation and
reading calibration tables.
REGISTER 1:
DS39566A-page 4
bit 7
bit 6-1
bit 0
PMCON1: PROGRAM MEMORY CONTROL REGISTER (ADDRESS: 18Ch)
Reserved: Read as ‘1’
Unimplemented: Read as ‘0’
RD: Read Control bit
1 = Initiates a FLASH read, RD is cleared in hardware. The RD bit can only be set (not cleared)
0 = Does not initiate a FLASH read
Legend:
S = Settable bit
W = Writable bit
‘1’ = Bit is set
bit 7
reserved
R-1
in software.
DD
range. It is indirectly
U-0
—
Advance Information
U-0
—
U = Unimplemented bit, read as ‘0’
R = Readable bit
‘0’ = Bit is cleared
When interfacing to the program memory block, the
PMDATH:PMDATL registers form a two-byte word that
holds 14-bit data for reads. The PMADRH:PMADRL
registers form a two-byte word that holds the 13-bit
address of the FLASH location being accessed. This
device can have up to 2K words of program FLASH,
with an address range from 0h to 07FFh. The unused
upper bits in both the PMDATH and PMADRH registers
are not implemented and read as zeroes.
PMADR
The address registers can address up to a maximum of
8K words of program FLASH.
When selecting a program address value, the MSByte
of the address is written to the PMADRH register and
the LSByte is written to the PMADRL register. The
upper MSbits of PMADRH must always be clear.
PMCON1 Register
PMCON1 is the control register for memory access.
The control bit, RD, initiates read operations. This bit
cannot be cleared, only set, in software. It is cleared in
hardware at the completion of the read operation.
U-0
—
U-x
—
 2002 Microchip Technology Inc.
U-0
—
-n = Value at POR
x = Bit is unknown
U-0
—
R/S-0
RD
bit 0