PIC16CE62X
The code for these functions is not yet determined, but
will be available on our web site (www.microchip.com)
when it is completed. The code will be accessed by
either including the source code FLASH62X.INC or by
linking FLASH62X.ASM.
6.0
EEPROM PERIPHERAL
OPERATION
The PIC16CE623/624/625 each have 128 bytes of
EEPROM data memory. The EEPROM data memory
supports a bi-directional 2-wire bus and data transmis-
sion protocol. These two-wires are serial data (SDA)
and serial clock (SCL), that are mapped to bit1 and bit2,
respectively, of the EEINTF register (SFR 90h). In
addition, the power to the EEPROM can be controlled
using bit0 (EEVDD) of the EEINTF register. For most
applications, all that is required is calls to the following
functions:
6.0.1
SERIAL DATA
SDA is a bi-directional pin used to transfer addresses
and data into and data out of the memory.
For normal data transfer SDA is allowed to change only
during SCL low. Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.
; Byte_Write: Byte write routine
;
;
;
Inputs:EEPROM Address
EEPROM Data
EEADDR
EEDATA
6.0.2
SERIAL CLOCK
Outputs:
Return 01 in W if OK, else
return 00 in W
This SCL input is used to synchronize the data transfer
from and to the memory.
;
; Read_Current: Read EEPROM at address
currently held by EE device.
6.0.3
EEINTF REGISTER
;
;
;
Inputs:NONE
Outputs:
The EEINTF register (SFR 90h) controls the access to
the EEPROM. Figure 6.1 details the function of each
bit. User code must generate the clock and data sig-
nals.
EEPROM Data
EEDATA
Return 01 in W if OK, else
return 00 in W
;
; Read_Random: Read EEPROM byte at supplied
address
;
;
;
Inputs:EEPROM Address
Outputs: EEPROM Data
EEADDR
EEDATA
Return 01 in W if OK,
else return 00 in W
FIGURE 6-1: EEINFT REGISTER (ADDRESS 90h)
U-0
-
U-0
-
U-0
-
U-0
-
U-0
-
R/W-1
R/W-1
R/W-1
EESCL
EESDA
EEVDD
R
W
U
= Readable bit
= Writable bit
= Unimplemented bit,
read as ‘0’
bit7
bit0
- n = Value at POR reset
bit 7-3: Unimplemented: Read as '0'
bit 2:
EESCL: Clock line to the EEPROM
1 = Clock high
0 = Clock low
bit 1:
EESDA: Data line to EEPROM
1 = Data line is high (pin is tri-stated, line is pulled high by a pull-up resistor)
0 = Data line is low
bit 0:
EEVDD: VDD control bit for EEPROM
1 = VDD is turned on EEPROM
0 = VDD is turned off EEPROM (all pins are tri-stated and the EEPROM is powered down)
Note: EESDA, EESCL and EEVDD will read ‘0’ if EEVDD is turned off
1998 Microchip Technology Inc.
Preliminary
DS40182A-page 29
MICROCHIP [ MICROCHIP ]
