platform_i2c_test_for_efm8_ioexpander

Platform - I2C Test for EFM8 IOExpander

Overview

This project provides a test tool for EFM8 IOExpander. The example uses the I2C module for communication, a GPIO pin and a built-in LED to detect and signal the interrupts of EFM8 IOExpander. The command line interface also contains simple command interpreters to read and write registers of EFM8 IOExpander. Furthermore, some additional commands are added to make the example as a basic automated test tool. See AN1304: GPIO Expander Based on EFM8MCU Product Family for more information.

Gecko SDK version

• GSDK v4.4.3

Hardware Required

• EFM32MG12 Wireless Starter Kit (WSTK) Board

• EFM8BB52 8-bit MCU Pro Kit - BRD5206B

NOTE: Tested boards for working with this example:

Board ID	Description
BRD4161A	EFM32MG12 Wireless Starter Kit (WSTK) Board

Connections Required

The following picture shows the system view of how it works.

Setup

To test this application, you can either create a project based on an example project or start with an "Empty C Project" project based on your hardware.

Create a project based on an example project

1. Make sure that this repository is added to Preferences > Simplicity Studio > External Repos.

2. From the Launcher Home, add your hardware to My Products, click on it, and click on the EXAMPLE PROJECTS & DEMOS tab. Find the example project by filtering "ioexpander".

3. Click the Create button on the Platform - I2C Test For EFM8 IOexpander (IOEXP) example. Example project creation dialog pops up -> click Create and Finish and Project should be generated.

4. Build and flash this example to the board.

Start with an "Empty C Project" project

1. Create an Empty C Project project for your hardware using Simplicity Studio 5.

2. Copy the all attached files in the src and inc folders into your project (overwriting existing).

3. Open the .slcp file. Select the SOFTWARE COMPONENTS tab and install the software components:

   • [Third Party] → [Tiny printf]

   • [Platform] → [Driver] → [LED] → [Simple LED] → default instance name: led0

   • [Services] → [Command Line Interface] → [CLI Instance(s)] → default instance name: inst.

   • [Platform] → [Radio] → [RAIL Utility] → default instance name: inst.

   • [Driver] → [GPIOINT]

   • [Services] → [IO Stream] → [IO Stream: EUSART] → default instance name: vcom and configure as bellow:

   • [Platform] → [Board] → [Board Control] → enable: Virtual COM UART.

   • [Platform] → [Driver] → [I2C] → [I2CSPM] → add instance name: ioexp and configure as follows:

4. Build and flash the project to your device.

Run EFM8BB52 IOExpander project on EFM8 Board

1. From the Launcher Home, add your hardware to My Products, click on it, and click on the EXAMPLE PROJECTS & DEMOS tab. Find the example project by filtering "ioexpander".

2. Click the Create button on the EFM8BB52 IOExpander example. Example project creation dialog pops up -> click Create and Finish and Project should be generated.

3. Build and flash this example to the board.

How It Works

The EFM32MG12 plays the role of an I2C central device. The EFM8BB52 Pro Kit plays the role of an I2C peripheral device. They are connected via their expansion header, see Connections Required.

After resetting or powering on, the central device tries to identify the connected device. Therefore, it is necessary to power on the peripheral device first. When initialization is finished, the program is ready to execute commands through the serial console. This console can be the built-in tool of Simplicity Studio v5 or a third-party tool such as Putty, MobaXterm, etc. Type help to see the available commands:

COMMAND	DESCRIPTION
loop	Execute commands repeatedly
addr	Get/Set I2C slave address
read	Read register from IOEXP
write	Write register of IOEXP
mod	Read Modify Write a register of IOEXP
sleep	Set a waiting time period (msec)
time	Get current system time
ver	Get build information

Note:

• Most of the commands are self-explaining except mod and loop commands.

• A common limitation of commands is that they can use a maximum of 20 parameters.

The mod command realizes a read-modify-write process where the modification can be an arithmetic or bitwise operation. The function behind mod command: REG OP= VAL (i.e. mod 0x05 + 0x10 -> 0x05 += 0x10).

Loop command realizes repeated execution of a command or sequence of commands. The first parameter of the loop command is the loop counter. If the loop counter is zero, the result is an infinite execution of the command sequence. The infinite execution can break by pressing CTRL-C. As a loop command parameter, it is possible to use only the starting letter of other commands.

The application relies mostly on the command line interface part. However, a callback is registered to the PA09 (pin 10 on the Expansion Header of the central device). The GPIO pin interrupts to signal when the connected device generates an interrupt. The LED0 shows the current state. With the reading of available ports, IOExpander can acknowledge the interrupt.

The application is organized along with functionality. The command interpreter functions are placed in the cli_cmd_function.c file. while the gpio.c file includes the previously mentioned callback function (gpio_callback()). The ioexp_drv.c file is a simplification of the bsp_stk_ioexp.c on the one hand. Because the unused parts (such as functions, and configuration dependencies) are removed. On the other hand, it is extended as well. The get and set I2C address of the peripheral device and the multiple register reading or writing are new parts.