Microchip Technology AC164139 Data Sheet

 2010 Microchip Technology Inc.

DS39969B-page 223

The Inter-Integrated Circuit™ (I

2

C™) module is a serial

interface useful for communicating with other periph-
eral or microcontroller devices. These peripheral
devices may be serial EEPROMs, display drivers, A/D
Converters, etc.
The I

2

C module supports these features:

• Independent master and slave logic
• 7-bit and 10-bit device addresses
• General call address, as defined in the I

2

C protocol

• Clock stretching to provide delays for the 

processor to respond to a slave data request

• Both 100 kHz and 400 kHz bus specifications
• Configurable address masking
• Multi-Master modes to prevent loss of messages 

in arbitration

• Bus Repeater mode, allowing the acceptance of 

all messages as a slave regardless of the address

• Automatic SCL 
A block diagram of the module is shown in Figure 16-1.

The details of sending a message in Master mode
depends on the communications protocol for the device
being communicated with. Typically, the sequence of
events is as follows:
1.

Assert a Start condition on SDAx and SCLx.

2.

Send the I

2

C device address byte to the slave

with a write indication.

3.

Wait for and verify an Acknowledge from the
slave.

4.

Send the first data byte (sometimes known as
the command) to the slave.

5.

Wait for and verify an Acknowledge from the
slave.

6.

Send the serial memory address low byte to the
slave.

7.

Repeat steps 4 and 5 until all data bytes are
sent.

8.

Assert a Repeated Start condition on SDAx and
SCLx.

9.

Send the device address byte to the slave with
a read indication.

10. Wait for and verify an Acknowledge from the

slave.

11. Enable master reception to receive serial

memory data.

12. Generate an ACK or NACK condition at the end

of a received byte of data.

13. Generate a Stop condition on SDAx and SCLx.

This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to the
“PIC24F Family Reference Manual”,
Section 24. “Inter-Integrated Circuit™
(I

C™)” (DS39702). The information in

this data sheet supersedes the information
in the FRM.