Client of Master Channel Tutorial

This document describes a simple implementation of an IIC client +using the master channel functionality.

Purpose

This tutorial explains how to use the IIC platform service API +as a master and to communicate with a peripheral using half-duplex.

Intended Audience

Device driver writers.

Required Background

Before you start, you must:

Have installed +the platform specific implementation of IIC channels that is required +to support the IIC platform service API.
Include the IIC.dll in the kernel.iby file.
Include the iic.h and iic_channel.h header files.

The code example fragments are for synchronous operation. +For asynchronous operation, the buffers must be allocated on the heap.

Implementing +the IIC platform service

The Following tasks will be covered +in this tutorial:

Performing read/write +operations.

Basic Procedure

The implementation +on which the following code examples are based is implemented IIC +via a SPI bus. On hardware with dedicated IIC ports, the IIC port +would be specified and the header data type would be TConfigIICV01.

The high level steps to performing read/write operations are +shown here:

First set the +bus type, the channel number and the slave address.

An example +of this is :
// Configure the port. + busId.SetBusType(DIicBusChannel::ESpi); // Specify which multi-wire bus is to be used. in this example, SPI. + busId.SetChanNum(0); // Set the channel number. + busId.SetSlaveAddr(13); // Set the slave address.
Configure the +channel.

An example of which, is :
// create header - this configures a SPI port. + const TConfigSpiV01 TestHeader = + { + ESpiWordWidth_8, // Set the word width. In this example, 8 bits. + 260000, // Set the clock speed of the port. In this example, 260KHz. + ESpiPolarityLowRisingEdge, // Set the clock mode value. In this example, Active high, odd edges. + 500, // Set the timeout period. In this example, 500msec. + EBigEndian, // Set which endian is to be used. In this example, BigEndian is used. + EMsbFirst, // Set which bit order is to be used. In this example, the Msb is first. + 0, // Set the number of transaction wait cycles. In this example, 0. + ESpiCSPinActiveLow // Set the Chip select active mode. In this example, chip select is active low. + };
Make linked +lists of the transfers that are to be carried out.

An example +of this is :
// Set the transaction header. + TPckgBuf<TConfigSpiV01> header(TestHeader); + + // Set up a transmit transaction. + // This txTransfer buffer acts as the start of the transaction linked list. + TIicBusTransfer txTransfer(TIicBusTransfer::EMasterWrite, 8, &txTransferBuf); + + // Set up a receive transaction. + TIicBusTransfer rxTransfer(TIicBusTransfer::EMasterRead, 8, &rxTransferBuf); + + // Add to the receive transaction to the transaction linked list. + txTransfer.LinkAfter(&rxTransfer); + + // Create a transaction using header and the transaction linked list. + TIicBusTransaction transaction(&header, &txTransfer);
Use the IicBus::QueueTransaction() method, specifying the configuration +of the port and the start location of the transaction linked lists. +This queues the transactions on to the selected IIC channel.

An example of this is :
// Queue the transaction. + // Once this command has been executed, the value of r should be KErrNone. + r = IicBus::QueueTransaction(busId.GetConfig(), &transaction);