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Getting started with the STEVAL-ILL057V1 demonstration board

AN4460

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DocID026129 Rev 1

Getting started with the STEVAL-ILL057V1

demonstration board

This section aims to help designers to correctly power up and control the demonstration

board in a short time. It describes how the board is connected to the load and how the serial

command line and the board buttons control the light/color of the LED strings.

The STEVAL-ILL057V1 board provides 4 independent LED channels and the user can

connect up to 4 different LED chains (not included in the STEVAL-ILL057V1 package). The

board is configured to control standard LEDs with a forward voltage (VF) between 2.9

(“V_LMIN”) and 4.2 (“V_LMAX”) on each LED. The limits are defined in the firmware and

they can be changed by modifying the source code (see [#define V_LMIN] and [#define

V_LMAX] into “led.h”). Alternatively, the user can simulate the required voltage drop by

configuring, via the (ln command) an apparent incorrect number of LEDs.

The LED numbers and the current associated are configured via the serial command

defined in Section 7.3 on page 28.

The board accepts a DC input power in the range 12 V - 48 V. The user chooses the correct

input voltage depending on the LED numbers and the voltage drop. The firmware accepts

a minimum voltage of 2.8 V (“V_COM_MIN”) across the inductances when the MOSFET is

ON. If an incorrect power voltage value is set up, the LED current is not regulated correctly

but the STLUX385A prevents the external LED module from damage. The only way to

damage an external LED module is to configure a current over the maximum accepted by

the LED module or define a number of LEDs different from those used. When a new LED

module is applied to the board, it is recommended the user to start with the minimum current

(“lc x 0") and with the dimming OFF (“ll x 0). Note that the firmware stores the last serial

commands (LED number, LED current, LED dimming and adaptive voltage compensation

enable/disable) on the internal E2PROM and applies those values at power-on or reset.

First power-on procedure

The following section describes a step-by-step procedure, which guarantees a correct

power-on during the first configuration of the board.

The guide assumes that the following elements are available:



STEVAL-ILL057V1 board



USB TTL serial cable shipped with the board



Power supply



Computer running Windows operating system



LED string

It is recommended the LED string to be disconnected before the first startup.

The first power-on instructions as follows:

Connect the USB TTL serial cable to the USB port of the computer. Windows

recognizes the cable as a TTL and launches the driver installation.

Install the appropriate USB TTL serial cable drivers. The drivers are the “virtual COM

port (VCP)” and they are provided by FTDI (www.ftdichip.com). Should you need any

help install the drivers, please refer to your IT administrator. Once the drivers are

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