I/O Expander

Configure an I/O Expander device

• SDK directory: apps/sensors/io_expander

API Features Demonstrated

• Event Handling API
  • zn_event_register_periodic
• Peripherals/IO Expander API
  • io_expander_dir_set_all
  • io_expander_pol_set
  • io_expander_val_get
  • io_expander_val_set

Requirements and Prerequisites

This app requires a ZentriOS device, such as an AMWx06-E03 (Moray), connected via the I2C interface to a TCA6416A I/O expander.

Description

This app demonstrates control and monitoring of the I/O Expander, which adds additional Input/Output to a ZentriOS device.

The app configures an input port on the IO Expander to control the value of an output port on the I/O Expander.

If the input pin is wired to a button, and the output pin is wired to a LED, pressing the button turns the LED on, and releasing the button turns the LED off.

Usage Instructions

Open a ZentriOS serial terminal to the device. See Getting Started, Opening a ZentriOS Terminal.

Build, download and run the app. The app displays the following on the ZentriOS terminal:

> Initializing ap

Implementation

zn_app_init

• logs the Initializing ap message
• Calls configure_pins

configure_pins

• calls io_expander_dir_set_all to set the direction of the button input.
• calls io_expander_pol_set to set the polarity of the LED output.
• calls zn_event_register_periodic to set up an event handler update_led to poll the value of the button input.

update_led

• calls io_expander_val_get to get the value of the button input.
• depending on the value of the button input, sets the value of the LED output with io_expander_val_set

Source

See:

• io_expander.c
• platform.c
• platform.h