PICDEM2 datasheet(30/60 Pages) MICROCHIP

30 / 60 page

 2001 Microchip Technology Inc.

DS30374D-page 25

I2C/EEPROM Demo

5.2 MSSP Module

This section presents flowcharts to implement communication with Serial

EEPROM using the MSSP module in master mode. For SSP operation, refer

to Section 5.1.

5.2.1

Main Routine

The main routine is actually preceded by several register file, bit and vector

assignments (Figure 5.2). The program begins by configuring PORTB as

outputs and PORTC as inputs. The output data value will be read from

PORTB, so it is initialized to one.

The next part of the code initializes the MSSP module for master I2C mode.

The slew rate control is disabled and the clock rate is set to 100 kHz. Both the

RC3 and RC4 pins are made inputs as the MSSP module will control the data

direction.

Interrupts are not used in this program, so they are disabled. Also, the MSSP

is configured to enable I2C master mode.

The write/read loop begins with the initialization of the EEPROM address to

00h, and the device address to A0h. Then the write loop executes by writing

the output data value to each address in the EEPROM (Figure 5.3). After the

write loop, the EEPROM address and device address are re-initialized for

read. The read loop executes by reading data values for each EEPROM

address and verifying their accuracy (Figure 5.4).

After the read loop, the output data value is incremented by one and this

value displayed, via PORTB, on the LEDs. Then the write/read loop begins

again.

If an error is encountered when writing or reading the EEPROM, or if an

EEPROM value read is incorrect, the program jumps to the error loop, which

flashes the LEDs (Figure 5.5).

PICDEM2 数据表(PDF) 30 Page - Microchip Technology