APPLICATION NOTE
Atmel AT01244: DALI Slave Reference Design
Atmel 8-bit Microcontrollers
Features
•
•
•
Compliant with international standard IEC62386-101, 102, 207
Reference firmware design includes application, service and drivers
Reference hardware made of three main parts:
• DALI interface, which bridges the voltage between DALI bus and microcontroller
• Microcontroller, which communicates with DALI master and controls the LEDs
• LED driver, which drives the LED controlled by microcontroller
Description
DALI (Digital Addressable Lighting Interface) is an international standard created for
lighting control and now becomes one of the more popular lighting interfaces today.
DALI protocol is a digital communication interface with master-slave structure, aiming
as a control gear between power supply and LED.
DALI slave communicates with DALI master based on half duplex signal with baud
rate of 1200 bit/s. Frame is defined as the sequence of bits used to transmit data.
Forward frame is from master to slave and backward from slave to master. The
definition of bit and frame can be found in IEC62386-102.
Figure 1 shows the DALI slave system block diagram based on Atmel® megaAVR®
device.
Figure 1.
DALI slave system block diagram.
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 not limitations to manufacture
the reference hardware solution for the design.
42071B−AVR−07/2013
Table of Contents
1. Related Items ....................................................................................... 3 2. Hardware Modules ............................................................................... 4 2.1 DALI hardware interface ................................................................................... 4 2.2 Microcontroller................................................................................................... 4 2.3 LED driver ......................................................................................................... 4 3. Firmware Modules ............................................................................... 6 3.1 Drivers ............................................................................................................... 6 3.2 Service .............................................................................................................. 6 3.2.1 Frame State Convert........................................................................... 6 3.2.2 Frame message process .................................................................... 7 3.3 Application ........................................................................................................ 8 3.4 Logarithm dimming table ................................................................................... 9 3.4.1 high_PWM_val and low_PWM_val ..................................................... 9 3.4.2 flash_fade_rate_val and flash_inv_fadetime_val .............................. 10 Appendix A. Command Sets .............................................................. 13 Appendix B. Schematic ...................................................................... 15 Appendix C. Revision History ............................................................ 18 Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
42071B−AVR−07/2013
2
1.
Related Items
The following list contains links to the most relevant documents, software, and tools for DALI slave:
•
IEC 62386-101, IEC 62386-102, IEC 62386-207
The IEC standards define the specific of DALI slave.
•
Atmel ATmega88PA datasheet
ATmega88PA is the microcontroller used in this solution.
•
Atmel LED Drivers-MSL2041/MSL2042 datasheet
MSL2041 is used as LED driver.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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2.
Hardware Modules
As previously described, there are mainly three hardware modules.
2.1
DALI hardware interface
DALI hardware interface bridges the voltage level between DALI bus and microcontroller. According to the DALI
protocol, the HIGH level is 9.5V to 22.5V, and the LOW level is -6.5V to 6.5V. The special logic level should be
converted to the logic which MCU can accept. The interface logic should be 0 to 5V for the MCU (Atmel ATmega88PA)
used in this design.
Figure 2-1. DALI hardware 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:
•
•
•
2.2
Suitable for all working temperature range
Trim the input waveform of signal for MCU
Tolerant the difference of components for mass production
Microcontroller
ATmega88PA is one of the most popular devices in the Atmel MCU family. It is used as the main microcontroller in this
reference design. ATmega88PA handles the commands and data which comes from the DALI interface part.
2.3
LED driver
Atmel MSL2041 is used as the LED driver in this design. It drives and controls the LEDs based on the input PWM signal
from MCU. It also monitors the current and voltage of LEDs and feeds back to MCU the error status if error occurs.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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Figure 2-2. DALI LED driver.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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3.
Firmware Modules
The firmware is developed based on layer structure as Atmel ASF that makes it more convenient to port between
different Atmel device platforms. From bottom to top, the structure includes:
•
Drivers
Drivers are used to transmit DALI bits between top layer and afford timer.
Timer0 is defined for DALI encode/decode and DALI frame timing.
PCINT is used for DALI decode.
Timer1 is used for fade timing and other system timing.
•
Service
Service processes frame sequence timing and implement DALI commands. To make migration feasible
between different MCU device series, the service should be hardware irrelevant.
•
Application
Application realizes the DALI LED slave function. Besides DALI service, it also process power on, interface
state detection, etc.
Figure 3-1. DALI firmware structure.
3.1
Drivers
The driver layer aims at timer and encode/decode of DALI bits. For Atmel Atmega88PA in this solution, PCINT and
timer0/1 are chosen as the driver components. It is free to use other components if different method is used. PCINT
detects the logic change in the input signal pin after initialization. The signal change triggers the PCINT interrupt and
makes ISR handle the decode process.
Timer0 is configured as the time base for DALI encode/decode. It needs to count fast enough to measure the 1200 bit/s
bit rate in DALI data stream. Timer0 needs to work together with PCINT to decode DALI signal. Timer1 is mainly used
as time base for LED power output dimming.
3.2
Service
3.2.1
Frame State Convert
Firstly DALI slave goes into idle state and does state initialization. After this, the slave shall go to forward frame state
immediately and wait for receiving DALI frame.
If received, DALI frame should be processed. According to different conditions, it goes to next repeat state, backward
state or idle state. There is time delay between state conversions according to the IEC62386-102 standard
specification.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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In DALI standard definition, every configuration command shall be received twice within 100ms to reduce the probability
of incorrect reception. If received correctly twice, the configuration command should be executed and then go to idle
state. Otherwise it goes to idle state.
A backward frame shall only be sent after the reception of a query command or a write memory command. If backward
frame is NO, the DALI slave should not react. Otherwise it should send the DALI answer signal to master. After this is
done, it should go to idle mode with a delay.
Figure 3-2. Frame State Convert diagram.
next repeat
frame
need repeat
new frame
Idle
3.2.2
Forward
frame
need answer
Backward
frame
Frame message process
After DALI slave receives forward frame, it should decode the two bytes of address and data. The address type includes
short address, group address and broadcast. Address and data compose the command code. For every command
code, the corresponding defined function should be executed. In this module, the slave shall decode the address and
call the command function.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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7
Figure 3-3. Message process flowchart.
Y
Short address?
N
Y
Group
address?
N
Y
Broadcast?
N
N
N
Special
commands?
Y
Is me?
Y
N
Y
Commands
256-275?
Y
Process
commands 256275
Direct ARC?
Process direct
power level
N
Process normal
commands 0-255
Return
3.3
Application
The whole system process is an infinite loop. After start up, it initializes the parameters and configures microcontroller
blocks. In the first power on period, if no command affecting power level is received, it shall go to power on level
immediately without fading. The system also processes frame, interface state detection sequentially.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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Figure 3-4. Message process flowchart.
Start up
Initialize
param eters,
drivers
N
Power on
state?
Y
Process power on
Process fram e
Process interface
state
3.4
Logarithm dimming table
Here describes the dimming lookup table used in firmware.
3.4.1
high_PWM_val and low_PWM_val
DALI standards define the logarithmic dimming curve between power value and power level. The formula below defines
their relation.
where X denotes power value and n denotes power level.
Power level ranges from 1 to 254, while corresponding power value ranges from 0.1% to 100%. Figure 3-5 shows their
relationship.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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Figure 3-5. Logarithm dimming curve.
In this example, 12-bit PWM of the MCU is used to output power. PWM provides a duty ratio from 0 to 4095 which
corresponds to a precision of min. 0.1% power value. The PWM duty ratio lookup table is stored in arrays
high_PWM_val and low_PWM_val. The tables are stored in EEPROM to save FLASH space.
Timer1 is used as the time base for 12-bit PWM. The initialization is done in function dali_tc_init().
/*Timer1 clock with 8 prescaling */
tc_write_clock_source(TC1, TC_CLKSEL_DIV8_gc);
/* OC1B in Compare Match, PB2 output, non-inverting, Fast PWM,
* ICR1 is top*/
TCCR1A = (0 << COM1A1) | (0 << COM1A0) | (1 << COM1B1) | (0 << COM1B0) | (1 << WGM11) | (0 << WGM10);
TCCR1B |= (1 << WGM13) | (1 << WGM12);
/* Used as top value for PWM, 0x0fff makes this a 12-bit PWM */
ICR1 = TC1_TOP;
/* Clear counter */
TCNT1 = 0;
3.4.2
flash_fade_rate_val and flash_inv_fadetime_val
DALI standard defines FADE TIME and FADE RATE as light dim parameters. FADE TIME is the time taken for the light
to change from the current dim level to the target dim level. FADE RATE is the speed of the light change.
There are sixteen levels in the formula that:
•
•
FADE TIME = 2(X/2-1)
FADE RATE = 253 / (FADE TIME)
Their value relationship is given in Table 3-1.
Table 3-1.
FADE TIME and FADE RATE.
X
FADE TIME [s]
FADE RATE [steps/s]
0
1
2
3
No fade
0.7
1.0
1.4
Not applicable
358
253
179
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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4
5
6
7
8
9
10
11
12
13
14
15
2.0
2.8
4.0
5.7
8.0
11.3
16.0
22.6
32.0
45.3
64.0
90.5
127
89.4
63.3
44.7
31.6
22.4
15.8
11.2
7.9
5.6
4.0
2.8
In this design, Timer1 is used as timer of FADE TIME and FADE RATE, and its overflow interrupt is used as time base
for light dimming.
32-bit variable dali.long_level is used to store power level whose lower 24 bits is the fractional value and upper 8 bits is
the actual DALI level.
union daliunion {
//dali.long_level is used during fade - allows smoother fading between fixed DALI levels.
uint32_t long_level;
struct {
// Lower three bytes store the fractional value of DALI level
uint8_t byte0;
uint8_t byte1;
uint8_t byte2;
// Upper 8 bits dali.level is the actual DALI level.
uint8_t level;
};
}dali;
For DALI commands UP and DOWN, FADE RATE is used for light dimming. In every timer period, the change of DALI
level is FADE RATE divided by Timer1 overflow frequency. Thus a 25-bits result is got with lower 24 bits used as
fractional. To save space while keep precision, the result is right-shifted by 9 bits and the remainder 16-bits value is
stored in lookup table flash_fade_rate_val. And accordingly in application, the value from lookup table should be leftshifted by 9 bits before being used.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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For DALI direct power control command, FADE TIME is used for light dimming. In every timer period, the change of
DALI level is (1/FADE TIME) divided by Timer1 overflow frequency. Thus a 17-bits result is got. Also to save space, the
result is right-shifted by 1 bit and the remainder 16-bits value is stored in lookup table flash_inv_fadetime_val. And
accordingly in application, the value from lookup table should be left-shifted by 1 bit before being used. To dim N levels
in power control command, the above result needs to be multiplied by N.
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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Appendix A.
Command Sets
Command number
Command name
–
0
1
2
3
4
5
6
7
8
9
10 – 15
16 – 31
32
33
34 – 41
42
43
44
45
46
47
48 – 63
64 – 79
80 – 95
96 – 111
112 – 127
128
129
130 – 143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
DIRECT ARC POWER CONTROL
OFF
UP
DOWN
STEP UP
STEP DOWN
RECALL MAX LEVEL
RECALL MIN LEVEL
STEP DOWN AND OFF
ON AND STEP UP
ENABLE DAPC SEQUENCE
Reserved
GO TO SCENE
RESET
STORE ACTUAL LEVEL IN THE DTR
Reserved
STORE THE DTR AS MAX LEVEL
STORE THE DTR AS MIN LEVEL
STORE THE DTR AS SYSTEM FAILURE LEVEL
STORE THE DTR AS POWER ON LEVEL
STORE THE DTR AS FADE TIME
STORE THE DTR AS FADE RATE
Reserved
STORE THE DTR AS SCENE
REMOVE FROM SCENE
ADD TO GROUP
REMOVE FROM GROUP
STORE DTR AS SHORT ADDRESS
ENABLE WRITE MEMORY
Reserved
QUERY STATUS
QUERY CONTROL GEAR
QUERY LAMP FAILURE
QUERY LAMP POWER ON
QUERY LIMIT ERROR
QUERY RESET STATE
QUERY MISSING SHORT ADDRESS
QUERY VERSION NUMBER
QUERY CONTENT DTR
QUERY DEVICE TYPE
QUERY PHYSICAL MINIMUM LEVEL
QUERY POWER FAILURE
QUERY CONTENT DTR1
QUERY CONTENT DTR2
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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158 – 159
160
161
162
163
164
165
166 – 175
176 – 191
192
193
194
195
196
197
198 – 223
224 – 254
255
256
257
258
259
260
261
262 – 263
264
265
266
267
268
269
270
271
272
273
274
275
276 – 349
Reserved
QUERY ACTUAL LEVEL
QUERY MAX LEVEL
QUERY MIN LEVEL
QUERY POWER ON LEVEL
QUERY SYSTEM FAILURE LEVEL
QUERY FADE TIME/FADE RATE
Reserved
QUERY SCENE LEVEL (SCENES 0-15)
QUERY GROUPS 0-7
QUERY GROUPS 8-15
QUERY RANDOM ADDRESS (H)
QUERY RANDOM ADDRESS (M)
QUERY RANDOM ADDRESS (L)
READ MEMORY LOCATION
Reserved
See parts 207 of this standard
QUERY EXTENDED VERSION NUMBER
TERMINATE
DATA TRANSFER REGISTER (DTR)
INITIALISE
RANDOMISE
COMPARE
WITHDRAW
Reserved
SEARCHADDRH
SEARCHADDRM
SEARCHADDRL
PROGRAM SHORT ADDRESS
VERIFY SHORT ADDRESS
QUERY SHORT ADDRESS
PHYSICAL SELECTION
Reserved
ENABLE DEVICE TYPE X
DATA TRANSFER REGISTER 1 (DTR1)
DATA TRANSFER REGISTER 2 (DTR2)
WRITE MEMORY LOCATION
Reserved
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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14
Schematic
1 Q101A 6
R101
GND_DALI
5
Appendix B.
150k
4
3
BC857BS Q101B
BC857BS
1
1
BAT54XV2T1G
R103
1.0M
C101
4.7uF
U101
2
R105
1.0M
GND_DALI
D102
MMSZ4682-V
4
VCC_5V
3
SFH6156-3
1
7.5k
D101
2
2
R102
DALI_Input
R104
8.2k
2
C102
1n
GND
GND_DALI
GND_DALI
GND_DALI
U102
R106
1.0M
1
2
GND_DALI
3
R107
240k
C103
OUT
V+
5
VIN+
IN-
4
TLV3491
TLV3491AIDBVR
100p
4
Q102
BC847B
J101
D103
GND_DALI
TP101
GND_DALI
+
R108
1.5k
DALI_VP
1
~
2
-
GND_DALI
3
2
DALI connector
GND_DALI
~
1
VCC_5V
R109
1R
TP102
DALI_GND
R110
360R
Q103
BC817-25
120R
GND_DALI
U103
4
R111
3
1
2
R112
100R
SFH6156-3
GND_DALI
DALI_Output
GND_DALI
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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15
C301
U301
VIN
3
EN
OUT
BYPASS
TP301
J301
VCC_5V
GND
4.7uF
C304
10n
TP302
C303
33n
C302
4
GND
GND
GND
GND
GND
GND
GND_TEST
J313
GND
GND
TP303
5V
5
2
4.7uF
LP2985-50DBVR
1
2
1
GND
VIN_12V
VIN_12V
INPUT
VCC_5V
DALI_Input
VCC_5V
TP304
TP305
OUTPUT
R301
10k
SCL
Driver_SCL
R303
100k
DALI_Output
R302
10k
TP306
Driver_SCL
SDA
Mega_RST
Driver_SDA
Driver_SDA
180k
NCP18WF104J03RB
GND
C305
33n
VCC_5V
GND
C307
33n
VCC_5V
1
2
3
4
5
6
7
8
PD3(OC2B/INT1/...)
PD4(XCK/T0/...)
GND
VCC
GND
VCC
PB6(XTAL1/...)
PB7(XTAL2/...)
VCC_5V
D301
620R
3 R306
R
1
G
2
LED2
SML-020MLT
R307 620R
ATmega88PA-AU
TP307
V_LED
LED_voltage
(.../ADC1)PC1
(.../ADC0)PC0
ADC7
GND
AREF
ADC6
AVCC
(.../SCK)PB5
TP308
24
23
22
21
20
19
18
17
V_S0
C309
100nF R308
Driver_S0
100k
GND
Mega_AREF
VCC_5V
J310
C308
33n
GND
TP309
2
4
6
HEADER 2x3
VCC_5V
Driver_S0
C306
33n
PWM
Driver_PWM
1
3
5
LED_voltage
GND
9
10
11
12
13
14
15
16
4
(.../INT0)PD2
(.../TXD)PD1
(.../RXD)PD0
(.../RESET)PC6
(.../ADC5/SCL)PC5
(.../ADC4/SDA)PC4
(.../ADC3)PC3
(.../ADC2)PC2
U302
R305
2
PD5(OC0B/T1/...)
PD6(OC0A/AIN0/...)
PD7(AIN1/...)
PB0(CLKO/ICP1/...)
PB1(OC1A/...)
PB2(SS/OC1B/...)
PB3(OC2A/MOSI/...)
PB4(MISO/...)
R304
1
GND_TEST
32
31
30
29
28
27
26
25
The thermistor need placed
close to the Power LED
Mega_MOSI
TP310
Driver_PWM
FLTB
Driver_FLTB
Driver_FLTB
GND
Mega_SCK
Mega_MISO
TP311
EN
Driver_EN
Driver_EN
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
42071B−AVR−07/2013
16
2
GND
5
C202
TDC-021H-1
4.7uF
R201
18k
4
GND
R202
10k
GND
EN
SW
FB
C201
6
JS201
D201
MSS2P3
100nF
L201
LQH44PN2R2MP0
C203
10u/25V
3
R203
R204
2.7k
150R
2
D203
Driver_PWM
Driver_FLTB
Driver_SCL
Driver_SDA
GND_DRIVER
FBO1
EN
PWM3
PWM2
PWM1
PWM0
FLTB
SCL
SDA
D0
G0
S0
D1
G1
S1
NC
FBI1
FBO2
FBI2
GND
VIN
VCC
CVDD
VDD
NC
D3
G3
S3
S2
G2
D2
NC
R207
10k
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
Driver_S0
LED_voltage
2
1
D205
LED_12
Short test
C204 1u
GND_DRIVER
Driver_VIN
Driver_VCC
GND_TEST
C205 2.2u
Q201
Si4168DY
Si4168DY
GND_DRIVER
Driver_VDD
4
C206 2.2u
GND_DRIVER
R209
360mR
GND_DRIVER
Driver_S0
LED_voltage
D204
LED_12
J203
8
7
6
5
GND_DRIVER
Driver_PWM
Driver_FLTB
Driver_SCL
Driver_SDA
330R
R205
120k
GND
GND_DRIVER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Current Test
3
2
1
Driver_EN
R206
MSL2041GU
R208
100k
Driver_EN
1
FDLL4148
VIN_12V
U202
J202
GND
GND
GND
VIN_12V
1
2
2
MSS2P3
U201 MP2451DT
1
VIN BST
12
1
1
D202
1
2
GND
3
2
1
2
J201
Driver_D0
Driver_G0
R210
360mR
GND_DRIVER
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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17
Appendix C.
Revision History
Doc. Rev.
Date
Comments
42071B
07/2013
Add hardware information in “Description” chapter
42071A
02/2013
Initial document release
Atmel AT01244: DALI Slave Reference Design [APPLICATION NOTE]
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18
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