View detail for Atmel AT04022: DALI Slave with XMEGA E Hardware User Guide

APPLICATION NOTE
Atmel AT04022: DALI Slave with XMEGA E Hardware User Guide
Atmel AVR XMEGA E
Features
•
•
Atmel® AVR® ATxmega32E5 microcontroller
DALI (Digital Addressable Lighting Interface) Slave Physical Interface
• Optocoupler translate signals between the DALI physical layer and the MCU
• Voltage conversion from DALI voltage level to MCU voltage level
•
Lighting Control
•
•
•
•
•
•
Buck converter
Up to 300mA LED current with External N-CH MOSFETS
1kHz PWM Input with Dimming Duty Cycle
Removable LED board to facilitate customer’s LED load connection
One dual LED is controlled by user
PDI Program/Debug interface
Description
The reference design of DALI Slave based on ATxmega32E5 is developed to
demonstrate DALI protocol functions. The reference hardware includes three
parts, DALI physical layer interface, MCU, and LED drive circuit. The LED string
is controlled by the DALI commands through the ATxmega32E5.
For this reference design, the hardware design files (schematic, BOM and PCB
Gerber) and software source code can be downloaded from Atmel website. The
provided hardware documentation can be used with no limitations to manufacture
the reference hardware solution for the design.
Figure 1.
DALI Slave with ATxmega32E5
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Table of Contents
1. Related items ..................................................................................... 3
2. Overview ............................................................................................ 4
2.1
2.2
2.3
2.4
Components for set up ...................................................................................... 4
Preprogramming firmware ................................................................................. 5
Power supply..................................................................................................... 5
Programming the kit .......................................................................................... 5
3. Connectors ........................................................................................ 6
3.1
3.2
3.3
3.4
PDI header ........................................................................................................ 6
Power Jack ....................................................................................................... 6
DALI BUS connector ......................................................................................... 6
LED Load and Temperature Sensor header ..................................................... 7
4. Peripherals ......................................................................................... 8
4.1
4.2
4.3
4.4
4.5
DALI physical layer interface............................................................................. 8
Buck LED Driver.............................................................................................. 10
LED Load ........................................................................................................ 11
LED Indicator .................................................................................................. 11
Temperature Sensor ....................................................................................... 11
5. Code examples ................................................................................ 13
6. Revision history................................................................................ 14
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1.
Related items
The following list contains links to the most relevant documents for the DALI Slave
•
ATxmega32E5/ ATxmega16E5/ ATxmega8E5 Preliminary Datasheet
ATxmega32E5 is the microcontroller used in this solution.
•
Atmel AVR XMEGA MANUAL
The document contains complete and detailed description of all modules included in the Atmel AVR
XMEGA E microcontroller family.
•
IEC 62386-101, IEC 62386-102, IEC 62386-207
The Digital Addressable Lighting Interface (DALI) was defined in IEC 62386.
•
AVR1612: PDI programming driver
The Program and Debug Interface (PDI) is an Atmel® proprietary interface for external programming and
on-chip debugging of the device. This application note describes how to implement PDI programming.
•
Atmel Studio 6
Atmel Studio 6 is a free Atmel IDE for development of C/C++ and assembler code for Atmel
microcontrollers.
•
Atmel JTAGICE3
JTAGICE3 is a mid-range development tool for Atmel 8- and 32-bit AVR microcontrollers with on-chip
debugging for source level symbolic debugging, Nano Trace (if supported by the device) and device
programming.
Atmel AT04022: DALI Slave with XMEGA E Hardware User Guide [APPLICATION NOTE]
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2.
Overview
The Atmel AVR DALI Slave based on ATmega32E5 kit is intended to demonstrate the Atmel AVR ATXmega32E5
microcontroller which is used to communicate with DALI master and light source. Figure 2-1 shows the available
features on the board.
Figure 2-1. Overview of DALI Slave kit with ATxmega32E5
2.1
Components for set up
The components in Table 2-1 are necessary for perform all functions of the reference design.
Table 2-1.
Components for kit setup
Component
Function
Reference hardware Kit
The main board and LED load
Power Supply
Power for the kit
Programming Tool with PDI interface
Debug and Programming
DALI Master
Control the Kit for simulate a normal lamp behavior
DALI BUS Power Supply
Provide Power Supply for DALI BUS
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2.2
Preprogramming firmware
The ATxmega32E5 on the kit is programmed with the default firmware. The detailed description of the firmware is
available in the AT03922 DALI Slave with XMEGA E – Software User’s Guide.
2.3
Power supply
The kit needs an external power supply which can deliver 12V and up to 500mA. The actual current requirement for
the board is much less than 500mA but in order to be able to power optional expansion boards this margin is
recommended.
The 12V is regulated down to 3.3V with an onboard LDO regulator, which provides power to the entire main board.
Please note that the 32MHz CPU clock frequency is used in this application, thus the VCC of the MCU must be
greater than 2.7V. Please refer to the datasheet of the ATxmega32E5 for more details.
The 12V voltage is converted to proper voltage and supply LED string.
2.4
Programming the kit
The kit can be programmed from an external programming tool through the PDI interface.
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3.
Connectors
The DALI Slave kit based on ATxmega32E5 has PDI header J3, Power Jack J4, DALI BUS connector J12 and LED
header J14. They are shown in Table 3-1
Table 3-1.
3.1
Connector and functions
Connector
Function
J3
PDI interface for programming and debug
J4
12VDC Power Jack
J12
DALI BUS connector
J14
LED Load and Temperature Sensor connector
PDI header
The AVR ATxmega32E5 can be programmed and debugged via PDI header. Any tools which carry the PDI
interface can program and debug the kit. JTAGICE3 is recommended here for programming. The definition of the
PDI interface can be found in Table 3-2.
Table 3-2.
3.2
AVR ATxmega32E5 programming and debugging interface - PDI
Pin on programming header
PDI
1
DATA
2
VCC
3
-
4
-
5
CLK
6
GND
Power Jack
The diameter of the Power Jack pin is 2mm, which is connected to DC+ of the power jack plug. The Jack spring is
connected to DC- of the power jack plug.
Table 3-3.
3.3
Power Jack
Pin on power jack
Name on the Power Jack
1
DC-
2
DC-
3
DC+
DALI BUS connector
The J12 is the DALI bus connector. It connects to the DALI bus directly. According to the DALI protocol, these pins
have no polarity requirement.
Table 3-4.
DALI BUS Connector
Pin on DALI BUS Connector
Name on the DALI BUS
1
DALI BUS
2
DALI BUS
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3.4
LED Load and Temperature Sensor header
The connector J14 provides a connection for the LED string and Temperature Sensor. The header is polarity
sensitive.
Table 3-5.
LED Load and Temperature Sensor header
Pin on LED Load header
Name on the LED Load header
1
V+
2
V-
3
VCC
4
NTC
5
GND
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4.
Peripherals
Figure 4-1 shows the DALI Slave system block diagram based on Atmel ATxmega32E5 device.
Figure 4-1. DALI Slave system block diagram
DALI RX
DALI bus
4.1
DALI
physical layer
Interface
PWM
ATxmega32E5
DALI TX
STATE
LED driver
DALI physical layer interface
The DALI physical layer interface bridges the voltage level between DALI bus and microcontroller ATxmega32E5
device. According to the DALI protocol, the HIGH level is from 9.5V to 22.5V, and the LOW level is from -6.5V to
6.5V. The logic level should be converted to the logic which MCU can accept. For the MCU ATxmega32E5 used in
this kit, the interface logic should be 0 to 3.3V. Figure 4-2 shows the diagram of the DALI physical layer interface.
Figure 4-2. DALI Physical Layer Interface
Current
Source
Optocoupler
MCU Rx
Comparator
DALI
Bus
Rectify
Bridge
Optocoupler
MCU Tx
Two optocouplers are used to isolate the voltage level between the DALI bus and microcontroller.
Using the comparator in above circuit has advantage over other simplified design in
•
Suitable for all working temperature range
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•
•
Trim the input waveform of signal for MCU
Big tolerance for the difference of components for mass production
The peripheral modules on ATxmega32E5 reduce the overhead of the firmware.
•
The USART module is connected to XMEGA Custom Logic (XCL) module and serial frame length can be
extended up to 256 bit. The combination of ATxmega32E5 LUT and USART can implement encoding and
decoding. The combination can receive and transfer data with Manchester code directly without external
firmware consumption.
For Manchester encoding, USART needs to operate in synchronous mode. SCK of USART is used as
Manchester clock signal. Transmit data from shift register is used as Manchester data. To encode the data,
XCL linked to USART is used to execute XOR logic. The logic output from XCL is connected to USART
TXD pin.
Figure 4-3. Manchester encoding
For Manchester decoding, since there is no synchronous input clock signal. USART runs in asynchronous
mode for data reception and PLC of LUT controls the variable length of data bits stream. The maximum
length of the stream is limited to 256 by PLC. EDMA can be used to receive data from USART receiver
register.
Figure 4-4. Manchester decoding
Atmel AT04022: DALI Slave with XMEGA E Hardware User Guide [APPLICATION NOTE]
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The connection from the DALI physical layer interface to the MCU is shown in Table 4-1.
Table 4-1.
4.2
The connection from the DALI physical layer interface to the MCU
Pin on AVR ATxmega32E5
DALI physical layer interface
PD2
DALI_INPUT
PD3
DALI_OUTPUT
Buck LED Driver
Buck converter and linear driver are used to drive LED string. Figure 4-5 shows the diagram of the BUCK LED
driver.
Figure 4-5. Diagram of BUCK LED driver
In the Buck converter, the MCU ATxmega32E5 generates the fixed 1MHz PWM to drive Q1 MOSFET, and the Buck
converter output proper voltage for LED string. When MCU detected the voltage at the Drain of the Q2 more than
1V, the MCU will immediately turn off the PWM signal, and then turn off the Q1 MOSFET. So the voltage of the C
will turn down until the voltage at the Drain of the Q2 less than 1V and then turn on Q1 MOSFET to provide power
for LED. This process is immediately achieved by on-chip hardware modules - linking the Event System Controller
module to the Fault Extension module in the ATxmega32E5.
In the Buck Converter circuit, the response speed of the Q1 MOSFET should be as fast as possible, and delay time
should be as short as possible between the PWM output of the MCU and the drive of the Q1 MOSFET. So the
accelerating circuit is needed in the BUCK Converter.
The linear driver is used to drive LED string. The MCU ATxmega32E5 generates the fixed 1kHz PWM to drive
external N-Ch MOSFET. And Change the duty cycle of the PWM for dimming at the user’s request. The transistor
Q3 and sample resistance Rs compose the constant-current circuit for LED. Figure 4-6 shows the current waveform
of the LED.
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Figure 4-6. Current Waveform of the LED
Table 4-2.
Pin on AVR ATxmega32E5
Buck Circuit PWM
PC5
PWM1_V
Table 4-3.
4.3
Buck Circuit PWM connection
Linear Driver of the LED connection
Pin on AVR ATxmega32E5
Linear Driver of the LED
PC6
PWM2_L
PA0
ILED_AC_IN+
LED Load
Pay attention that DO NOT look at the LEDs directly when they are lit. Otherwise LEDs may potentially harm the
user’s eyes.
4.4
LED Indicator
There is a dual LED (Red and Green) available on the board that can be used to indicate the working condition of
the kit. The green LED and the red LED can be individually activated by driving the connected I/O line to VCC. The
dual LED can also emit orange light when both red and green LEDs are activated.
Table 4-4.
4.5
LED connections.
Pin on AVR ATxmega32E5
LED
PD4
Green LED
PD5
Red LED
Temperature Sensor
The temperature sensor circuit uses a NTC resistor to sense the temperature of the LED load.
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Table 4-5.
Temperature Sensor connection.
Pin on AVR ATxmega32E5
Temperature Sensor
PA3
NTC
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5.
Code examples
The example application is based on the Atmel Software Framework that is included in Atmel Studio 6. The Atmel
Software Framework can also be found as a separate package online at:
http://www.atmel.com/tools/avrsoftwareframework.aspx.
For more information about the code example, see the application note AT03922: DALI Slave with XMEGA E –
Software User’s Guide.
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6.
Revision history
Doc. Rev.
Date
Comments
42174A
08/2013
Initial document revision
Atmel AT04022: DALI Slave with XMEGA E Hardware User Guide [APPLICATION NOTE] 14
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