ST STM32F-1 User manual

February 2014 DocID025866 Rev 1 1/31
UM1728
User manual
STM32F1xx DALI slave interface
Introduction
This document describes the implementation of the digital addressable lighting interface
(DALI) into the STM32F1xx 32-bit microcontroller family.
The DALI slave library for STM32F1xx microcontrollers simplifies integration of the DALI
slave interface into customer applications. The implementation of DALI into STM32,
together with the various STM32 features (peripherals, computation power, communication
interfaces), is mainly used in light control applications (example, electronic ballast control).
The STM32 DALI slave library was tested according to the DALI specification.
The DALI slave library comes with a simple application example (DALI slave device). The
example was designed (and tested) for use with the following evaluation boards:
•STM32VLDISCOVERY
•DALI transceiver board (see UM1032: STEVAL-ILM001V1 hardware module)
The application example controls the light of the on-board LED diode. Light intensity is
controlled by the PWM method using a built-in timer. The external DALI master device must
control this application example (which is the DALI slave device). The DALI master devices
were tested using the ST7DALI evaluation kit (master device board and PC software).
Useful information and links about DALI interface can be found on http://www.dali-ag.org.
www.st.com

Contents UM1728
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Contents
1 DALI information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 DALI standard overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.1 DALI purpose and properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.2 DALI physical layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.3 DALI stack layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 STM32 DALI slave library overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Structure of final user application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 User application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 I/O pin driver layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Function description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 I/O pin driver layer functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.1.1 STM32F10x_it.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.2 DALIslave.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 DALI stack layer functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 dali.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.2 dali_cmd.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.3 dali_pub.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2.4 dali_reg.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.5 eeprom.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.6 lite_timer_8bit.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2.7 dali_config.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4 Application setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5 Application description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6 Running the PC software for DALI-STM32 . . . . . . . . . . . . . . . . . . . . . . 26
6.1 Basic commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.2 Light level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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List of figures
Figure 1. Example of DALI device connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 2. Voltage and currents on the DALI bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 3. Structure of DALI stack layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 4. Structure of I/O pin driver layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 5. Hardware for testing DALI: STM32 discovery kit with DALI transceiver board and
ST7 DALI master board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 6. Bottom side connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 7. Schematic of connector J2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 8. STM32-discovery board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 9. Slave device setup (STEVAL-ILM001V1 and STM32-discovery board). . . . . . . . . . . . . . . 23
Figure 10. Master device setup (ST7 DALI master board) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 11. Complete DALI setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 12. Main window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 13. Search for ballast window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 14. Screen overview after a quick search. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 15. Light level window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 16. Ballasts window after clicking on update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 17. Light level window during fading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

DALI information UM1728
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1 DALI information
1.1 DALI standard overview
DALI is an international standard (IEC 62386) lighting control system that provides a single
interface for electronic control gears (light sources) and devices (lighting controllers).
The DALI standard enables dimmable ballasts, transformers, relay modules, emergency
fittings and controllers from different manufacturers to be mixed and matched into a single
control system. A DALI system provides designers, installers, building owners, facility
managers and end-users a powerful and flexible digital lighting system with security of
supply from many sources.
The DALI standard is overseen by the “AG-DALI” activity group which comprises engineers,
manufacturers, and institutions working in the field of digital lamp/ lighting control.
More information about the DALI standard can be found in the following documents:
•IEC 62386
•NEMA standard 243-2004
The following sections provide an overview of the DALI standard. They describe the basic
principles of the DALI interface.
Note: To better understand the STM32 DALIF1xx slave library, a knowledge of the DALI interface
specification is essential. This application note does not provide a description of this
specification.
1.1.1 DALI purpose and properties
The DALI protocol was designed to control modern light sources using a computer.
Functions include:
•Dimming
•ON/ OFF switching
•Grouping lights to a common control
•Scene storage and selection
The DALI design properties include:
•Simple wiring using standard electrical installation cables
•No special wiring topology (as with power electrical cables)
•Simple installation giving cable polarity independence
•Automated light source addressing
•Use of low cost microcontrollers on the light source side to minimize cost of light source
•Use of a simple protocol to control light dimming and switching.
1.1.2 DALI physical layer
The DALI interface consists of a physical layer from two wires. This is a simple installation
for which the polarity is independent.

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The protocol used on these cables is a standard serial protocol.There is 1 start bit, 8 data
bits and 2 stop bits.The communication speed is fixed at 1200 Bd.Manchester coding is
used for better resynchronization: rising edge is logical 1 and falling edge is logical 0.
Bytes are grouped into frames. One frame usually consists of 1 or 2 bytes which is either
data only (answer from the device) or address + data (command to device).
Voltage levels present on DALI communication wires are higher than the transistor-
transistor logic (TTL) levels that are usually used. This is due to better noise immunity
because of higher interference present on nearby power installation cables. Voltage levels
are defined as follows:
•Low level state
– -4.5 to 4.5 V (transmitter)
– -6.5 to 6.5 V (receiver)
•High level state
– 11.5 to 20.5 V (transmitter)
– 9.5 to 22.5 V (receiver)
Low level state is dominant on the DALI bus. The device can force this level to the DALI bus
by shortening the DALI wires. Consequently, current levels are defined for devices used on
the DALI bus. There are two device types:
1. DALI master or DALI slave communication devices. In these devices the current is
sunk from the DALI bus. They consume a maximum of 2 mA to receive high level state
and sink a minimum of 250 mA to transmit low level state.
2. DALI power supply. These devices power the DALI bus and are the source current for
it. Supply is limited to a maximum of 250 mA.
The maximum length of the DALI bus depends on the cables used for the DALI
communication wires (for example, a 1.5 mm2 cable (which is typically used in light
installation cables) allows a maximum bus length of up to 300 m.). The length is linearly
dependent on the cross section of the conductor.
Collisions between several DALI masters on the DALI bus are solved on the basis of timing
priorities. When a collision is detected (the DALI master should check the sent data),
communication is muted for a period of time according to the assigned master priority. There
are five defined priority levels: 12 ms, 13 ms, 14 ms, 15 ms, and 16 ms. The longest waiting
time has less priority.

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Figure 1. Example of DALI device connections
Figure 2. Voltage and currents on the DALI bus
1.1.3 DALI stack layer
The DALI stack is the higher DALI layer which implements DALI commands, DALI
structures, timing management, and error management according to the DALI specification.
The most important feature of the DALI stack layer is the DALI commands. These
commands are used for:
•Direct light control such as dimming, on/off switching, and scene selection.
•Device configuration to set DALI variables, read device properties, address
assignments, and query device status.
The DALI stack layer is fully implemented in microcontroller software.

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1.2 STM32 DALI slave library overview
The STM32F1xx DALI slave library contains instructions for implementing software of the
DALI protocol into STM32 microcontrollers.
The DALI slave library consists of two layers:
•Upper layer (DALI stack layer)
•Hardware layer (I/O pin driver layer)
The upper layer of the DALI slave library (also known as the DALI stack layer), consists of
routines for processing the required DALI commands and other necessary control functions
(including timing control, error management, memory management, and light control). The
hardware layer (also known as the direct I/O pin driver layer), contains the physical layer
implementation. This is necessary because STM32 microcontrollers do not support DALI
communication peripherals.

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2 Structure of final user application
The final user application uses the DALI slave library and so, consists of the following three
layers:
•Main user application
•DALI stack layer
•I/O pin driver layer
2.1 User application
The structure of the user application is comprised completely of IAR project files. The
application code is in one source file, “main.c”, in which the whole user ballast control is
implemented. This code calls the DALI slave library functions.
The user application example included in the DALI slave library package is designed to work
with the “STM32 discovery kit” and “STEVAL_ILM001V1 (DALI transceiver board)”. The
STM32 discovery kit is a small printed circuit board (PCB) with an integrated
STM32F100RBT6 device which demonstrates STM32 capabilities. The DALI transceiver
board is connected to the STM32 discovery kit as a physical layer extension. It provides
voltage level conversion and optical isolation between the DALI bus and the STM32
discovery kit (according to the DALI specification requirements).
The main task of the user application is to initialize the DALI stack and to implement the light
intensity control function (callback function). This function is ballast dependent. The user
application also periodically controls some event flags. If the DALI slave library sets an
event flag and it indicates a pending event, the user application must call the appropriate
service routines (from the DALI slave library) to execute the necessary commands.
The user application example uses timer 3 to control the light intensity of the LED diode
present on the STM32 discovery kit. Timer 3 generates the pulse-width modulation (PWM)
for the LED diode (using the callback function). The main program loop checks event flags,
executes actions for active flags, and provides power management (Low power state if the
DALI bus is quiet) and error management (reports hardware errors). For all these purposes
the user application calls functions from the DALI slave library.

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Figure 3. Structure of DALI stack layer
The DALI stack is hardware independent. It calls the I/O pin driver for low level hardware
dependent functions. After initialization of the DALI stack layer (after calling initialization
functions), most of the tasks run automatically. Tasks include receiving commands and
running timer tasks (light dimming, timeouts).
Note: To get the complete source code of DALI STACK library, please contact nearest sales office.
2.2 I/O pin driver layer
The I/O pin driver layer of the DALI slave library implements physical and link layers of the
DALI interface. The DALI protocol requires two pins for communication. The I/O pin driver
layer implements reception and transmission through direct control of two arbitrary GPIO
pins. It also controls the required DALI speed and correct bit timing, solves DALI bus error
recovery, and collects received bits into DALI frames (using address and command bytes).
Figure 4 displays the structure of the DALI I/O pin driver layer
Figure 4. Structure of I/O pin driver layer
The I/O pin driver layer occupies one timer (systick timer), one GPIO interrupt, one timer
interrupt, and direct control of two GPIO pins (assignment of which is software selectable).

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Timing events are invoked inside the timer interrupt service routine. Such events control the
I/O pin driver layer behavior by calling callback functions from the DALI stack layer at given
1 ms intervals (timer ticks).
Figure 5. Hardware for testing DALI: STM32 discovery kit with DALI transceiver board
and ST7 DALI master board