PIC32MX: I2C - Revision history

Andrew Long: /* I2C Master Code */

2009-09-28T18:44:25Z

I2C Master Code

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Andrew Long: /* I2C Master Code */

2009-08-18T16:10:42Z

I2C Master Code

Andrew Long at 16:09, 18 August 2009

2009-08-18T16:09:16Z

Andrew Long at 16:08, 18 August 2009

2009-08-18T16:08:34Z

Andrew Long: /* Methodology: Single Master System */

2009-08-18T16:05:14Z

Methodology: Single Master System

Andrew Long: /* I2C Master Code */

2009-08-18T15:58:31Z

I2C Master Code

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Andrew Long: New page: Inter-Integrated Circuit, or I2C (pronounced I squared C), is used as a serial communication between other devices including other PICs. I2C can be used in the following cases: **As a sl...

2009-08-18T15:29:40Z

New page: Inter-Integrated Circuit, or I2C (pronounced I squared C), is used as a serial communication between other devices including other PICs. I2C can be used in the following cases: **As a sl...

New page

Inter-Integrated Circuit, or I2C (pronounced I squared C), is used as a serial communication between other devices including other PICs.

I2C can be used in the following cases:
**As a slave device
**As a master in a single master system
**As a master in a multi-master system

I2C for PIC32 is discussed in more detail in the [http://ww1.microchip.com/downloads/en/DeviceDoc/61116D.pdf Microchip I2C documention].

==Available Pins==

There are two sets of pins for I2C. Each consists of SDAx and SCLx where x is either 1 or 2. SDA is the data pin and SCL is the clock pin.

==Methodology: Single Master System==

This section discusses the general approach for I2C between a single master and a slave.

To begin communication, the master first transmits a start command.

Each slave has a unique address. For the PIC32, the slaves can have either 7 bit or 10 bit addresses. For communicating with 10 bit addresses, see the [http://ww1.microchip.com/downloads/en/DeviceDoc/61116D.pdf Microchip I2C documention]. The master transmits an 8 bit number. Bits 7-1 make up the slave address and bit 0 indicates whether or not the slave is expected to read or write. If bit 0 is a 1, the data transfer is output from the slave. If bit 0 is a 0, the data transfer is input to the slave.

When the master transmits the 8 bit number, the slaves compare their address to the sent address. If there is a match, the slave automatically generates an acknowledge that is sent to the master.

The slave then must read the address and R/W bit. This is done to clear the buffer.

The master then either waits for a response (output from slave) or sends up to 8 bits of data (input to slave).
If output is from the slave, after each transmission the master sends an acknowledge. The slave continues to send data until the master does not acknowledge.

The master then either sends a restart condition to send or read more data or sends a stop condition. If the master sends a restart condition, the procedure above is followed.

==I2C Master Code==

This section details the master code for I2C between two PICs. The slave has a 7 bit address in this example.

==I2C Slave Code==

This section details the master code for I2C between two PICs. The slave has a 7 bit address in this example.

@@ Line 45: / Line 45: @@
 The Baud Rate Generator is used to set the SCL clock frequency. The equations used for the BRG are shown below:
 FSCK = (PBCLK) / ((I2CxBRG+2) * 2)
 I2CBRG = (PBCLK / (2 *FSCK)) - 2

@@ Line 28: / Line 28: @@
 The master then sends a stop condition.
+==C Code ==
-==I2C Master Code==
+===I2C Master Code===
 This section details the master code for I2C between two PICs. The slave has a 7 bit address in this example. What we are going to do is send a message to the slave and then read the same message back from the slave. If the correct message is read LEDs 2 and 4 will turn on. If there is an error, LED 3 will turn on.
@@ Line 192: / Line 192: @@
    }
-==I2C Slave Code==
+===I2C Slave Code===
 This section details the master code for I2C between two PICs. The slave has a 7 bit address in this example.
+==Associated Circuitry==
+The SDAx and SCLx pins must be connected to Vdd (power) with a resistor typically 2.4k Ohm. They must also be connected from the master to the slave.

@@ Line 2: / Line 2: @@
 I2C can be used in the following cases:
-**As a slave device
+*As a slave device
-**As a master in a single master system
+*As a master in a single master system
-**As a master in a multi-master system
+*As a master in a multi-master system
 I2C for PIC32 is discussed in more detail in the [http://ww1.microchip.com/downloads/en/DeviceDoc/61116D.pdf Microchip I2C documention].

@@ Line 27: / Line 27: @@
 If output is from the slave, after each transmission the master sends an acknowledge. The slave continues to send data until the master does not acknowledge.
-The master then either sends a restart condition to send or read more data or sends a stop condition. If the master sends a restart condition, the procedure above is followed.
+The master then sends a stop condition.
 ==I2C Master Code==