dorian’s ts1 systemes electroniques students conception of a digital to analog conversion board...
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Dorian’s TS1 Systemes Electroniques students
CONCEPTION OF A DIGITAL TOCONCEPTION OF A DIGITAL TOANALOG CONVERSION BOARDANALOG CONVERSION BOARD
ObjectiveObjective : :To conceive a Digital to Analog conversion board To conceive a Digital to Analog conversion board driven by a microcontroller, allowing the driven by a microcontroller, allowing the elaboration of an output triangular wave whose elaboration of an output triangular wave whose amplitude, offset and frequency are programmableamplitude, offset and frequency are programmable
Digital to Analogconversion board
MicrocontrollerNb Vo
CONCEPTION OF A DIGITAL TOCONCEPTION OF A DIGITAL TOANALOG CONVERSION BOARDANALOG CONVERSION BOARD
Limiting values :• Vomin = -10V• Vomax = +10V• Vo(peak to peak)min = 0V• Vo(peak to peak)max = 20V• Programmable frequency
Vo
Vomax=10V
Vomin=-10V
T=1/f
0 t
5V
-7.5V
Example:
• Vomax = 5V
• Vomin = -7.5V
• Vo(p-p) = 12.5V
• Offset = -1.25V
CONCEPTION OF A DIGITALCONCEPTION OF A DIGITALTO ANALOG BOARDTO ANALOG BOARD
Specification manual :We have to conceive 2 distinct Digital to Analog conversion boards :• the first one equipped with the 8 bits parallel inputs DAC DAC0832• the second one equipped with the 16 bits serial inputs DAC DAC714
Each conversion board will be driven by the evaluation boardMC68HC12A4EVB equipped with the Freescale 68HC812A4 16 bits µC
The programmation language will be C language
Optocouplers will be used in order to electricaly isolate digital partsfrom analog parts
SummarySummary
A : Parallel inputs Digital to AnalogA : Parallel inputs Digital to Analog conversion boardconversion board
B : Serial inputs Digital to AnalogB : Serial inputs Digital to Analog conversion boardconversion board
C : Comparison of both technologi-C : Comparison of both technologi- cal solutionscal solutions
A : Parallel inputs digital to analogA : Parallel inputs digital to analog conversion board conversion board
B : Serial inputs digital to analog conversion board
C : Comparison of both technologi- cal solutions
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC0832 (1 of 3)
• 8 bits resolution
• 2 current outputs IOUT1 and IOUT2
Needs addition of a Current to Voltage converter
• Single supply
• Capacity to operate in a double buffered configuration
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC0832 (2 of 3)
Bipolar mode configuration
To obtain -10 V < Vo < +10 V , we choose VREF = + 10 V
Thus, 1 LSB = 2.VREF/256 = 78 mV
So, -10 V < Vo < +9.92 V
Vo = VREF.(DIGITAL CODE – 128)/128
Remark : Although the DAC just needs a single supply, the OPAmpsof the Current to Voltage converter need a symetrical double powersupply V+/V- in order to deliver a bipolar output voltage
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC0832 (3 of 3)
The outputs IOUT1 and IOUT2are updated after the negativeedge of/WR, provided that theDAC is enabled(/CS=ILE=0)
The number Nb to convert must remain stable as long as /WR is low
We decide to drive the DAC with the /WR input exclusivelyand we will connect the other inputs (ILE and /CS) to their activelow level
We name the control signal driving the /WR input Conv_Ord(Conversion Order).This signal will be elaborated by the microcontroller
Conv_Ord
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
2. Elaboration of the reference voltage VREF = 10V
VZ = 1.233V
LM4041-ADJ
V+ = 15V
VZR1
R2
VREF
V+ = 15V
R1
Radj
VREF
Stable reference diode :VZ = 1.233 V +/- 12mV
VREF = VZ(1 + R2/R1)
Final proposition :
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
3. Block diagram of the digital to analog conversion
Current toVoltage
conversion
Digital toAnalog
conversion
IOUT1
IOUT2
Conv_Ord
NbVo
Referencevoltage
VREF=10V
8
* 9 digital input signals :• Conv_ord : Conversion Order signal
• Nb : Number varying between 0 and 255
* 1 analog output signal : Vo
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
4. The electrical isolation between digital and analog parts
µC
MC68HC812A4
Electricalisolation
Digital toAnalog
conversion+
Current toVoltage
conversion
Conv_Ord_d Conv_Ord
Nb_d Nb
0V_d 0V_a
Vo
o
Vcc=5V V+=15V
8
V-=-15V
8
Digitalparts
Analogparts
Optocouplers(x9)
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
5. The connection of ILQ74 optocouplers (1 of 2)
Vcc=5V V+=15V
GPIO
µC V
IF
V+=15V
GPIO
µC
V
IF
Diagram 1 Diagram 2
1
C
0
S
1
0
10
SC
0
1IOL
IOH
We prefer the non inverting diagram 1 IF[ILQ74] = IOL[68HC12]
Problem :IF[ILQ74] recommanded = 10 mAIOLmax[68HC12] = 2 mA
Need to add a buffer between the µC and the optocoupler
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
5. The connection of ILQ74 optocouplers (2 of 2)
Vcc=5V V+=15V
GPIO
µC V
IF
ILQ741
74LS645
IOLmax[74LS645] = 24 mAIF[ILQ74] = 10 mA
IOLmax[68HC12] = 2 mAIIL[74LS645] = 0.4 mA
Synthesis of used components
74LS645 : 8 buffers/deviceILQ74 : 4 optocouplers/device
1x74LS645 + 2xILQ74 for the isolation of Nb data
Buffer
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
6. Calculus of resistors used in conjunction with ILQ74 optocouplers
2
CTRmin.IFICsat
IF
5]VOL[74LS64-VF-VccR1
ICsat
VCEsat- (VR2
)
• R1 sets IF to 10 mA
• R2 imposes saturation of the optotransistor
• We choose
Vcc=5V V+=15V
GPIO
µC VCEsat
IF
ILQ74
1
74LS645
R1 R2
VOL[74LS645]
VF
ICsat
• Thus
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
7. The connection of SFH615 optocoupler
For the last data to isolate(Conv_Ord) we decide to use aSFH615 optocoupler (single optoper device) and to elaborate thebuffer with a PNP transistor
Vcc=5V V+=15V
GPIO
µC
VCEsat
IF
SFH615A-1
R2
VF
ICsat
2N2907AIB
R1
RB
VOL[68HC12]
IF
VF-907]VECsat[2N2-VccR1
1
0
C
S
C
S
1
0
IB
]VOL[68HC12-]VEB[2N2907-VccRB
2
CTRmin.IF o]ICsat[Topt
o]ICsat[Topt
to]VCEsat[Top-)(VR2
]min[2N2907h
IF2.IB
FE
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
8. Block diagram of the Digital to Analog conversion system
ConversionCourantTension
ConversionNumériqueAnalogique
IOUT1
IOUT2
Conv_Ord
NbVo
Tension deréférence
VREF=10V
8
Current toVoltage
conversion
Digital toAnalog
conversion
IOUT1
IOUT2
ReferenceVoltage
VREF=10V
8
Buffers+
Electricalisolation
Conv_Ord_d
Nb_d
88
µC68HC812
PF0
PH[0-7]
Digital to Analog conversion board
The conversion board is driven by 9 Input/Output Port pinsdeclared as outputs :
• PF0 : Conversion order signal (Conv_Ord)
• PH[0-7] : Number Nb to convert into an analog voltage
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
9. The electrical diagram
PH7
PH6
PH5
PH4
PH0
PH1
PH2
PH3
PF0
0V_a
0V_aNb-2
Nb-1
Nb-0
DI7Nb-7
DI6Nb-6
Nb-3
Nb-5
Nb-4
Dem_conv
OV_a
0V_a
0V_a
U3
ILQ74
G3
3 EN 1(BA)3 EN 2(AB)
1
2
2 18
3 17
4 16
5 15
6 14
7 13
8 12
9 11
19
1
U1
74LS645
R14
R13
R12
R11
U4
ILQ74
R22
R21
R20
R19
DI34
DI25
DI16
DI07
DI416
DI515
DI614
DI713 X
FE
R
17
ILE
19
WR
2
18
CS
1
WR
1
2
Vcc
20
RF
B
9
Vre
f
8
AG
ND
3
DG
ND
10
OUT111
OUT212
U5
DAC0832
R23
R24
R25
R26
3
21
84 U6:A
TL082
5
67
84
U6:B
TL082
R9
20k
R710k
R8
20k
2
1
3
DZ-REF
LM4041-ADJ
RAJUSTPOT
R6
R5
PTB
R15
R16
R17
R18
T2N2907 1
2
4
3
U2
SFH615
R2
R3
R4
0V_n
Vcc
Vcc V+
Vcc
Vcc
V+
V+
V+
V-
V+
V+
Tensions d'alimentations
Vcc = +5V par rapport au potentiel de référence numérique 0V_n
V+ = +15V par rapport au potentiel de référence analogique 0V_a
V- = -15V par rapport au potentiel de référence analogique 0V_a
0V_n OV_a
Vs
Carte de conversion numérique - analogiqueà entrées parallèles
BUFFERS
OPTOCOUPLERS
DAC
VOLTAGEREF
CURRENT TOVOLTAGE
CONVERTER
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
10. Production of a test program
Vo
Vomax=10V
Vomin=-10V
T=1/f
0 t
5V
-7.5V
• Vomax = 5V
• Vomin = -7.5V
• Vo(pk-pk) = 12.5V
• Offset = -1.25V
We suggest to elaborate the next output voltage :
• f = 0.1 Hz
Given that Vo = VREF.(Nb – 128)/128 we can deduce :
• For Vo = Vomin = -7.5V, Nb = Nbmin = 32• For Vo = Vomax = +5V, Nb = Nbmax = 192
To elaborate a full period T we will successively convert numbers Nb from 32 to 192 and then from 191 to 31
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
10. Flowchart of the test program : main function main()
In init() :
• Nbmin = 32
• Nbmax = 192
• PF0 and PH[0-7] Input/Output Port pins declared as outputs
Start
init()
Nbmin --» Nb
conversion(Nb)
(Nb+1) --» Nb
Nb=(Nbmax+1) ?
(Nbmax-1) --» Nb
conversion(Nb)
(Nb-1) --» Nb
Nb=Nbmin ?no
no
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
10. Flowchart of the test program: conversion(Nb) function
t0
t1
t2
t
• Start_Conv_Ord = 0xFE
• End_Conv_Ord = 0x01
Nb
t0 t1 t2
PORTH
PF0
delay(T) allows adjustmentof the frequency to the desiredvalue (here 0.1 Hz)
Start
delay(T1)
Nb --» PORTH
PORTF&Start_Conv_Ord --» PORTF
PORTF|End_Conv_Ord --» PORTF
delay(T2)
delay(T)
End
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
11. Laboratory activities
CONCEPTION OF THE PARALLEL INPUTS DIGITALCONCEPTION OF THE PARALLEL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
11. Laboratory activities : the output voltage
A : Parallel inputs digital to analog conversion board
B : Serial inputs digital to analogB : Serial inputs digital to analog conversion boardconversion board
C : Comparison of both technologi- cal solutions
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (1 of 6)
• 16 bits resolution
• The number Nb to convert must be serially transmitted :* MSB first* In synchronism with a clock signal
• The DAC must be enabled during transmission• After transmission of a number Nb, a low level pulse triggers conversion process
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (2 of 6)
DAC714 will be driven by a SPI (Serial Peripheral Interface) :
DAC714
/CLK
SDIMOSI
SCKSPI
/A0
/A1
µC
68HC812
GPIO
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (3 of 6)
DAC714
/CLK
SDIMOSI
SCKSPI
/A0
/A1
µC
68HC812
GPIO
Configuration of 68HC812 SPI :• Master mode
• MSB first transmission
• Transmission of data bits (Nb) in synchronism with negative edges of the clock signal
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (4 of 6)
The conversion of a 16 bits Nb needs 17 clock pulses :
ProblemProblem : The negative pulse on /A1 input must be elaborated in synchronismwith the positive edge of a 17th clock pulse.
/CLK
SDI
/A1
D15 D8 D7 D0
/A0
How can we solve the problem ?
??
But a SPI can elaborate multiple of 8 clock pulses exclusively.
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (5 of 6)
/CLK
SDI
/A1
D15 D8 D7 D0
/A0
A deep study of internal structure of the DAC714 shows that it can bedriven with the next control signals :
Thus the connections :
And the name given to thedifferent signals :
CLK
Nb
Conv_Ord
DAC_En
DAC714
/A0
SDIMOSI
SCKSPI
/CLK
/A1
µC68HC812
GPIOPS7
PS4
Nb
CLK
DAC_En
Conv_Ord
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
1. The main characteristics of the DAC714 (6 of 6)
The DAC714 can operate inunipolar or bipolar mode :
We choose to supply the DACwith a +15V/-15V power supply
Thus 1 LSB = 20/65536 = 305 µV
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
2. The electrical isolation between digital parts and analog parts
MC68HC812A4
Electricalisolation
Digital toAnalog
conversion
0V_d 0V_a
Vo
o
Vcc=5V V+=15V V-=-15V
Nb
CLK
DAC_En
Conv_Ord
Nb_d
CLK_d
DAC_En_d
Conv_Ord_d
MOSI
SCK
PS7
PS4
SPI
GPIO
Digitalparts
Optocouplers(x4)
Analogparts
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
3. The choice of HCPL2232 optocouplers
• The maximum frequency of SPI clock signal is 4 MHz
• ILQ74 :
This optocoupler cannot fit SPI specifications because the switching times ton and toff of the optotransistor are too long
Thus we choose HCPL2232 optocouplerwhich allows 5 Mbits/s data rates
Moreover, the input current IF is lowenough so that the µC can drive theoptocoupler without any buffer
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
4. The connection of HCPL2232 optocouplers
HCPL2232 DAC714
2V < VIH < V+ - 1.4V (13.6V)
. If we supply the HCPL2232 with 15V, we have VOH[HCPL2232] = 13.5V
Given that VIH[DAC714]max = 13.6Vwe will supply the HCPL2232 with 9V
.
VOH[HCPL2232] = 7.5V
GPIO
µC
V
IF
Vdd=9V
VOH[HC12]
R
Thus :1
10
0IF
VF-]VOH[68HC12R
Calculus of R :
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
5. Block diagram of the Digital to Analog conversion system
Nb
CLK
DAC_En
Conv_Ord
Electricalisolation
Digital toAnalog
conversion
Power supplyVdd = 9V
Vo
Nb_d
CLK_d
DAC_En_d
Conv_Ord_d
MOSI
SCK
PS7
PS4
SPI
GPIO
µC68HC812
Digital to Analog conversion board
The Digital to Analog conversion board is driven by :
• the 2 MOSI and SCK SPI pins
• the 2 PS4 and PS7 Input/Output Port pins declared as outputs
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
6. The electrical diagram
Dem_Conv
Nb
CLK
Val_CNA
Vs
Vdd=9V
PS4
PS5=MOSI
PS6=SCK
PS7
1
2
3
4
7
8
6
5
U2
HCPL2232
1
2
3
4
7
8
6
5
U3
HCPL2232
R1
1.2k
R2
1.2k
R3
1.2k
R4
1.2k
Vdd
/A13
SDI4
/A02
/CLK1
/CLR16
+Vcc
7
AC
OM
8
DC
OM
6
-Vcc
15
SDO 5
GAIN 14
OFFSET 13
RFB2 10
REFOUT 12
BIP 11
VOUT 9
U4DAC714
3
26
74 1 5
U5TL081
VI3 VO 1
GN
D2
U178L09
OV_a
OV_a
OV_a
OV_a
OV_a
OV_a
C3
100nF
C4
100nF
V+V-
V+
V+
V-
C6
100nF
C5
100nF
V+
C1220nF
C2100nF
Tensions d'alimentations
Vcc = +5V par rapport au potentiel de référence numérique 0V_n
V+ = +15V par rapport au potentiel de référence analogique 0V_a
V- = -15V par rapport au potentiel de référence analogique 0V_a
0V_n OV_a
Carte de conversion numérique - analogique à entrées sérielles
0V_n
Optocouplers
DAC
POWER SUPPLY
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
7. Production of a test program
Vo
Vomax=10V
Vomin=-10V
T=1/f
0 t
5V
-7.5V
• Vomax = 5V
• Vomin = -7.5V
• Vo(pk-pk) = 12.5V
• Offset = -1.25V
Same output voltage :
• f = 0.1 Hz
Given that 1 LSB = 20/65536V we can deduce :
• For Vo = Vomin = -7.5V, Nb = Nbmin = -24576• For Vo = Vomax = +5V, Nb = Nbmax = 16384
To elaborate a full period T we will successively convert numbers Nb from -24576 to 16384 and then from 16383 to -24575
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
7. Flowchart of the test program : main function main()
In init() :
• Nbmin = -24576
• Nbmax = 16384
• Configuration of the SPI
• The 2 PS4 and PS7 Input/Output Port pins declared as outputs
Start
init()
Nbmin --» Nb
conversion(Nb)
(Nb+1) --» Nb
Nb=(Nbmax+1) ?
(Nbmax-1) --» Nb
conversion(Nb)
(Nb-1) --» Nb
Nb=Nbmin ?no
no
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
7. Flowchart of the test program : conversion(Nb) function
DAC_En
Nb
Conv_Ord
D15 D8 D7 D0
CLK
t0
t1
t2
t3
t4
t
t0 t1 t2t3 t4
delay(T) allows adjustment of the frequency to the desired value (here 0.1 Hz)
Start
Enable DAC(DAC_En)=0
TransmitNb[15-8]
Transmissionover
?
TransmitNb[7-0]
Transmissionover
?
Conversion order(Conv_Ord) = 0 then 1
Disable DAC(DAC_En)=1
End
no
delay(T)
no
CONCEPTION OF THE SERIAL INPUTS DIGITALCONCEPTION OF THE SERIAL INPUTS DIGITALTO ANALOG CONVERSION BOARDTO ANALOG CONVERSION BOARD
8. Laboratory activities : the output voltage
A : Parallel inputs digital to analog conversion board
B : Serial inputs digital to analog conversion board
C : Comparison of both technologi-C : Comparison of both technologi- cal solutionscal solutions
COMPARISON OF BOTH TECHNOLOGICALCOMPARISON OF BOTH TECHNOLOGICALSOLUTIONSSOLUTIONS
• Parallel inputs board : 8 bits resolution / 1 LSB = 78 mV
• Serial inputs board : 16 bits resolution / 1 LSB = 305 µV
Performances of both boards are very different :
Let’s consider a 16 bits parallel inputs DAC : AD768
16 parallelinputs
2 current outputs
1 reference voltageinput
Same functionalities as the DAC0832 but with a 16 bits resolution
COMPARISON OF BOTH TECHNOLOGICALCOMPARISON OF BOTH TECHNOLOGICALSOLUTIONSSOLUTIONS
ConversionCourantTension
ConversionNumériqueAnalogique
IOUT1
IOUT2
Conv_Ord
NbVo
Tension deréférence
VREF=10V
Current toVoltage
conversion
Digital toAnalog
conversion
IOUT1
IOUT2
ReferenceVoltage
VREF=10V
Buffers+
Electricalisolation
Conv_Ord_d
Nb_d
µC68HC812
Parallel inputs DAC conversion board
16
1 GPIO
16 GPIO16
Nb
CLK
DAC_En
Conv_Ord
Electricalisolation
Digital toAnalog
conversion
Power supplyVdd = 9V
Vo
Nb_d
CLK_d
DAC_En_d
Conv_Ord_d
MOSI
SCKSPI
2 GPIO
µC68HC812
Serial inputs DAC conversion board
AD768 2 OPAmps
LM4041
1 SFH615 +4 ILQ74 +17 Buffers17 GPIO
1 SPI
2 GPIO 2 HCPL2232
DAC714
78L09
Belaïd
Daoudi
Mathieu Sylvain
Pierrick Raphaël Hervé
Yves
Fayçal
Sarah
Mickaël
Cédric
Morgan
Maureen
MathieuStephen SoundarRomainThanks a lot for your attention
Belaïd
Daoudi
Mathieu Sylvain
Pierrick Raphaël Hervé
Yves
Fayçal
Sarah
Mickaël
Cédric
Morgan
Maureen
MathieuStephen SoundarRomain