1. Finite State Machine & PIC-C I2C Communication

2. I2C Basics I2C is a Bus. Serial is point-to-point
Master and Slave pair
Master must start the communication
Slave can only respond
Slave has a 8-bit address
Bit 0 is reserved for direction control

3. Basic I2C Bus Setup SDA SCL MASTER SLAVE 1 SLAVE 2 5V
Pull-up Resistors
SDA
SCL

4. i2C Commands in PIC-C Master Only Slave Only Master & Slave
I2c_start()
I2c_stop()
Slave Only
I2c_isr_state()
Master & Slave
I2c_read()
I2c_write()

5. Communication example
MASTER
SLAVE
I2c_start()
I2c_write(slave addr | 0)
I2c_write(data)
I2c_stop()
i2c_read()
Data = i2c_read()
interrupt state = 0
interrupt state = 1

6. A slave->master read example
I2c_start()
I2c_write(slave addr | 0)
I2c_write(command)
I2c_write(slave addr | 1)
Data1 = I2c_read()
Data2 = I2c_read(0)
I2c_stop()
i2c_read()
Cmd = i2c_read()
I2c_read()
I2c_write(data1)
I2c_write(data2)
interrupt state = 0
interrupt state = 1
No i2c_stop()
interrupt state = 0x80
No Interrupt
interrupt state = 0x81

7. Data flow and slave ISR state
Data Transmission (Green = Slave -> Master)
0xB0
0x01
0xB1
0x11
0x22
Slave ISR State 1
0x80
0x81

8. Download examples via SVN from

9. Finite State Machine

10. Finite State Machine 2

11. Dual-I2C PIC I2c 1 Serial I2c 2 Sensor 1 Sensor 2 (Software Based)
GoGo Board
I2c 1
(Software Based)
Serial
I2c 2
(Hardware Based)

12. Creating dual i2c ports // i2c1 - Master
#use i2c(MASTER, SDA=PIN_B1, SCL=PIN_B2, stream=i2c_sensor)
// i2c 2 - SLAVE
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0xB0, FORCE_HW, stream=i2c_gogo)
// Example of use
I2c_start(i2c_sensor);
I2c_read(i2c_gogo); …