ST AN2786 APPLICATION NOTE

AN2786

Application note

STEVAL-IHI001V1 demonstration board: washing machine

user interface based on the ST7LITE49M and STLED316S

Introduction

The STEVAL-IHI001V1 is a demonstration board designed to simulate the user interface of
a modern washing machine.

The board is based on the low-cost 8-bit ST7LITE49M microcontroller equipped with an I²C
bus interface, and the STLED316S serial interfaced 6-digit LED controller with key-scan.

The demonstration board is designed to work as a stand-alone application, or as a
motherboard for the STEVAL-IHI002V1 daughter board, which features the STMPE1208S
capacitive sensing device and can be plugged into the STEVAL-IHI001V1 to operate as a
capacitive single touch keyboard.

June 2008 Rev 1 1/10

www.st.com

Contents AN2786

Contents

1 STLED316S: serial interfaced LED controller with key-scan . . . . . . . . 3

2 Demonstration board application schematic . . . . . . . . . . . . . . . . . . . . . 4

3 Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 STEVAL-IHI001V1 demonstration board photos . . . . . . . . . . . . . . . . . . 7

5 References and related materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2/10

AN2786 STLED316S: serial interfaced LED controller with key-scan

1 STLED316S: serial interfaced LED controller with

key-scan

The device used for the washing machine user interface is a compact LED controller and
driver. It interfaces with the MCU through a simple 3-wire serial interface.

The STLED316S drives up to 56 LEDs connected in a common anode configuration.
Individual digits may be addressed and updated directly, without re-writing the entire display
panel.

The maximum segment current is set through a single external resistor (R

Additionally, the STLED316S includes key scanning for an 8x2 key matrix, which
automatically scans a matrix of up to 16 keys.

Figure 1. Product application diagram example

SET

).

The STLED316S is equipped with an internal display RAM memory to store the data
transmitted from the MCU through the serial interface.

The device is programmed through a variety of read/write commands that permit the user to
set the display panel and manage the keyboard.

To avoid scanning the keyboard repeatedly searching for a pressed key, an additional IRQ
signal can be connected to the MCU. An interrupt is generated whenever a key is pressed.

3/10