Tutorial 5b - indicator LED on IOE

This tutorial will show you how to add LEDs to an I/O expander.

It is assumed the reader is familiar with LEDs from tutorial_5a_LED_on_uC.md and familiar with I/O expanders from tutorial_4c_split_keyboard_with_IOE.md.

Adding LEDs to the basic breadboard keyboard

The breadboard keyboard modifies the split breadboard keyboard described in tutorial_4c_split_keyboard_with_IOE.md

Add components to the breadboard as shown in the picture.

The two clear plastic cylinders are red and yellow LEDs. Each LED is in series with a 4.7k Ohm current limiting resistor. LED anodes (the longer lead) are powered by pins GPA5 and GPB4. LED cathodes (the shorter lead) are connected to a grounded terminal strip.

keybrd sketch with LEDs on IOE

The keybrd_5b_LED_on_IOE.ino sketch will run on the above breadboard keyboard.

The sketch demonstrates:

• multiple layers
• split keyboard
• LED on controller
• LED on IOE write port
• LED on IOE read port