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