Download - Mixed Signal PSoC based System
A . S. Powar, S. K.Tilekar and B.P. Ladgaonkar.
VLSI Design and Research CenterPost Graduate Department of Electronics
Shankarrao Mohite Mahavidyalaya, AklujTal - Malshiras , Dist. - Solapur – 413 101
• Introduction
– Origin of the Problem
– PSoC
• Designing of the System
– Hardware & Software Co-design
• Result and Discussion
• Conclusion
WHY HIGHTECH POLYHOUSE TECHNOLOGY ?
Temperature
Controlling Unit
Humidity
Sensor
SY-HS-220
Temperature
Sensor
AD 590
Microcontroller
AVR
Atmega8L
Power
Supply
+5V
+9V
-9V
Offset Voltage
Compensator
(741)
Liquid Crystal
Display
(16x2 lines)
In System
Programming
Instrumentation
Amplifier
AD 620
Instrumentation
Amplifier
AD 620
Humidity
Controlling
Unit
Phototransistor
BPW34
Instrumentation
Amplifier
AD 620
ADC FPGABuffer Amplifier
Weak
analog
signal
P rogrammable
S ystem
o n
C hip
PSoCWeak
analog signals
CO2 sensor (MG-
811) &
Humidity sensor
(SY-HS-220)
PSoC 1 Device
CY8C29466 -
24PXI
LCD
o Highly precise and reliable.
o Exhibit linearity over 30%Rh to 95 % Rh.
o The humidity sensor is of Capacitive type.
o Provides DC output voltage.
o Good sensitivity and selectivity to CO2 .
o Low humidity and temperature dependency.
o Long stability and reproducibility.
Overall chemical reaction:Li2CO3 + 2Na + = Na2O + 2Li + + CO2
EMF = Ec - (R x T) / (2F) ln (P(CO2)) Where, P(CO2) - CO2 partial Pressure, Ec - Constant Volume, R - Gas Constant volume, T - Absolute Temperature (K), F- Faraday constant
CO2 sensor (MG-
811) &
Humidity sensor
(SY-HS-220)
PSoC 1 Device
CY8C29466 -
24PXI
LCD
Inputs : Each pin can sink 25mA
Programmable filters
Flexible sensor interface I/O
3 types of ADCs, up to 4
Processing :
Outputs : Each pin can source 10mA
Up to 16 PWMs, Timers, Counters
Up to 9-bit DACs, 14-bit ADCsSupport Functions :
EEPROM
Sleep Options
Watch Dog Timer
Low voltage detect
Fast M8 Microcontroller Core
Multiply Accumulate
ADCINCVR
LCD
PGA
Block Diagram of ADCINCVR
Vo =(VIN –VGND).(Ra/Ra+Rb)+VGND
I = V/R
Q = CV
I average = Q/T = Qfs = CVfs
R equivalent = V/I average = 1/Cfs
Execute boot program:--initialise general purpose resources;--configure application specific modules;--initialise run time environment;--disable interrupt;call main application routine;
Void main(){Start system timers;Initialise application specific modules;Initialise global variables;Initialise application specific channels;Enable interrupts;While(1)
{Wait for events(Enabled interrupts);Read values from input channels;Execute control
procedure & computeactuation data;output actuation data to outputchannels;
}}
B) Application programme routine
A) Boot programme algorithm
Start
Initialization of
all modules
Get ADC reading
Get reading for CO2
Display reading
Convert in ASCII
Calibrate data for
Humidity
If
count<0x65(
200mv)
R
Display as DetectedDisplay as Undetected
NoYes
Software Design Flow Of
Our System
y = 0.0288x + 11.315
0
20
40
60
80
100
120
0 1000 2000 3000 4000
Series1
Linear (Series1)
Humidity(%Rh) Output(mV)
30 794
35 860
40 958
45 1092
50 1258
55 1458
60 1709
65 1894
70 2064
75 2224
80 2383
85 2547
90 2729
95 2935
Comparision
Sr.No.
Parameter AVR ATmega 8L
System
CY8c29466 PSoCsystem
1 Power 300mW 130mW
2 Cost(₹) X X-400
3 Time 3-4 days 2-3 hours
System is designed for measurement of humidity and CO2 gas.
The humidity observations shown by the system are highly reliable and
precise. Moreover, the presence of CO2 gas is also exhibited by the
present system. System works successfully and gives the data of humidity
and CO2 very precisely.
o Particularly for measurement of carbon dioxide (CO2)gas concentration, the calibration in the respectiveunits is required. However, presently due tounavailability of CO2 gas chamber the calibration ofcarbon dioxide gas concentration is left as futurework.
o Implementation of the system for mote.
References:
1.Introduction to Mixed-Signal, Embedded Design- Alex N. Doboli and Edward H. Currie.
2. CYPRESS MICROSYSTEMS “PSoC TM The Configurable Mixed Signal array With on-chip controller.
3. An Architecture for a Configurable Mixed-Signal Device Monte Mar, Member, IEEE, Bert Sullam, Member, IEEE, and Eric Blom IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 38, NO. 3, MARCH 2003.
4. P.E. Allen and D.R. Holberg, CMOS Analog Circuit Design – 2nd Ed., OxfordUniversity Press, 2002.5. R.J. Baker, H.W. Li and D.E. Boyce, CMOS Circuit Design, Layout, andSimulation, IEEE Press, 1998