WEATHER MONITORING SYSTEM User Requirements Design a weather

WEATHER MONITORING SYSTEM

User Requirements Design a weather monitoring system that detects the following parameters � Temperature � Pressure � Relative humidity � Wind Speed � Wind Direction � Rainfall � Solar Radiation This information is sent to a remote system every 5 minutes

All parameters sensed - every minute

Every 5 minutes – data collected Averaged & sent to Central computer

Communication is Serial Wired RS 232 C in null Modem Communication Speed is 9600 Baud

Temperature Range: - 20° C to + 50° C Resolution - 1° C

Wind Speed Range: 0 -100 MPH Resolution: 0. 5 MPH

Wind Direction Range: 0 to 360° Resolution: 2 o

Pressure Range: 800 -1100 millibars Resolution: 2 millibars

Humidity- Relative Humidity Range: 0 -100% Resolution: 1%

Solar Radiation Range: 0 -1500 W/m 2 Resolution: 10 W/m 2

Rainfall Range: 0 -20 mm/min Resolution: 0. 1 mm /min

WEATHER MONITORING SYSTEM Step 1 of the Design

WHERE TO START ?

SENSORS • Analog Output • Varying Current • Varying Voltage • Serial Digital output • Pulses/ Second

TEMPERATURE SENSOR SYSTEM SPECIFICATIONS • Range: - 20° C to +50° C • Resolution: - 1° C WE 700 • Output: 4 -20 m. A • Range: -50° C to + 50° C • Resolution: 2° F or 1° C • Operating Voltage: 10 -36 VDC • Warm Up Time: 5 seconds minimum • Operating Temperature: 50°C to +100°C -

WIND SPEED SENSOR SPECIFICATIONS WE 550 • Range: 0 -100 MPH • Resolution: 0. 5 MPH • Output: 4 -20 m. A • 0 -100 MPH • Resolution: . 5 MPH over the range 11 to 55 MPH • Operating Voltage: 10 -36 VDC • Warm Up Time: 3 seconds minimum • Operating Temp: -40° to +55°C

WIND DIRECTION SENSOR SPECIFICATIONS WE 570 • Range: 0 to 360° • Output 4 -20 m. A • Resolution: 2 o • Range 0 to 360° • Sensitivity 1 m/s (2. 2 mph) • Resolution 1% full scale • Operating Voltage 10 to 36 VDC • Warm-up Time 3 seconds minimum • Operating Temperature: -40° to +55°C

BAROMETRIC PRESSURE SENSOR SYSTEM SPECIFICATION • Range: 800 -1100 millibars • Resolution: 2 millibars WE 100 • Output: 4 -20 m. A • Range: 800 -1100 millibars • Resolution: 0. 5% of full scale • Operating Voltage: 10 -36 VDC • Warm Up Time: 3 seconds minimum • Operating Temp: -40° to +55°C ,

RELATIVE HUMIDITY SYSTEM SPECIFICATIONS WE 600 • Range: 0 -100% • Output: 4 -20 m. A • Range: 0 -100% RH • Resolution: 1% • Resolution: + 0. 5% RH • Operating Voltage: 10 -36 VDC • Current Draw: 3 m. A plus sensor • Warm Up Time: 3 seconds minimum • Operating Temp: -40° to +55°C

SOLAR RADIATION SENSOR SPECIFICATIONS WE 300 • Range: 0 -1500 W/m 2 • Resolution: 10 W/m 2 • Output: 4 -20 m. A • Range: 0 -1500 W /m 2 • Resolution: 1% of full scale • Operating Voltage: 10 -36 VDC • Warm Up Time: 3 seconds minimum • Operating Temperature: -40°C to +55°C.

RAINFALL SYSTEM SPECIFICATIONS LAMBRECHT – PRECIPITATION SENSOR • Range: 0 -20 mm/min • Output: 4 -20 m. A • Range: 0 -25 mm/m • Resolution: 0. 1 mm /min • Resolution: 0. 1 mm/min • Operating Voltage: 10 -36 VDC • Current Draw: 3 m. A plus sensor • Warm Up Time: 3 seconds minimum • Operating Temp: -40° to +55°C

OUTPUT SYSTEM SPECIFICATIONS • Communication is Serial • Wired • RS 232 C in null Modem • Communication Speed is 9600 Baud 16550

TIMING SYSTEM SPECIFICATIONS • Every 5 minutes – data collected • Every 1 Minute – Data Sensed 8253/8259

WEATHER MONITORING SYSTEM Step 2 Interfacing the sensor

STEP 2 : HOW TO INTERFACE SENSOR TO SYSTEM • Analog Current 4 -20 m. A • Generally Measure Voltage • Current to Voltage Conversion ? ?

CURRENT TO VOLTAGE CONVERSION 1. 25 0 V 6. 25 5 V

ANALOG TO DIGITAL • 7 Analog outputs from 0 -5 V • Size of ADC • Resolution of sensor • 19. 6 mv ( 8 -bit ADC) • (5. 0 – 0. 0 )V/256

SENSOR RESOLUTION VS ADC RESOLUTIONS TEMPERATURE SENSOR • Range: - 20° C to +50° C • Resolution: - 1° C • 70 • 5/70 • 71. 4 m. V ADC • 256 • 19. 6 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS WIND SPEED SENSOR ADC • Range: 0 -100 MPH • 256 • Resolution: 0. 5 MPH • 19. 6 m. V • 200 • 5. 0/ 200 • 25 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS WIND DIRECTION SENSOR ADC • Range: 0 to 360° • 256 • Resolution: 2 o • 19. 6 m. V • 180 • 5. 0/ 180 • 27. 78 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS PRESSURE SENSOR ADC • Range: 800 -1100 millibars • 256 • Resolution: 2 millibars • 150 • 5. 0/ 150 • 33. 3 m. V • 19. 6 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS RELATIVE HUMIDITY SENSOR ADC • Range: 0 -100% • 256 • Resolution: 1% • 19. 6 m. V • 100 • 5. 0/ 100 • 50 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS SOLAR RADIATION SENSOR ADC • Range: 0 -1500 W/m 2 • 256 • Resolution: 10 W/m 2 • 19. 6 m. V • 150 • 5. 0/ 100 • 50 m. V

SENSOR RESOLUTION VS ADC RESOLUTIONS RAINFALL SENSOR ADC • Range: 0 -20 mm/min • 256 • Resolution: 0. 1 mm /min • 19. 6 m. V • 200 • 5. 0/ 200 • 25 m. V

STEP 2 : HOW TO INTERFACE SENSOR TO SYSTEM • No of analog i/ps-7 • 8 -channel ADC • 8 -bit • 0808 – 8 channel, 8 -bit ADC

CLK IN 0 IN 1 IN 2 IN 3 IN 4 IN 5 IN 6 IN 7 DB 0 – DB 7 AD 0 AD 1 AD 2 EOC OE Analog I/ps VREF+ VREF- 5 V 0 V Supply Vcc GND SOC ALE ADC 0808 5 V 255 = 19. 6078 m. V

INTERFACE THE ADC

How to interface ADC to 8086 ? ■ 2 ports available use it for ADC

1 MHz CLK PB 0 –PB 7 PC 0 PC 1 PC 2 INTR PC 3 PC 4 PC 5 IN 0 IN 1 IN 2 IN 3 IN 4 IN 5 IN 6 IN 7 DB 0 – DB 7 AD 0 AD 1 AD 2 EOC OE SOC VREF+ VREFVcc GND ALE ADC 0808 sensors 5 V 0 V Supply

Generate 1 MHz ■ Use 8254 ■ Any other timing ■ Read every 1 Minute

STEP 3 : 1 MHz clock & 5 MIN Interrupt ■ Use 8254

5 MHz 5 V GATE 0 100 Hz 5 V CLK 0 OUT 1 GATE 1 CLK 2 5 V GATE 2 OUT 0 1 MHz ADC CLK Count = 5 d mode 3 CLK 1 mode 2 OUT 2 mode 2 5 MHz Count = 50000 d 1 minute Count =6000 d TIMER INT

STEP 4: Interrupt Generation ■ Use 8259

INT IR 0 Timer INTA IR 1 ADC 8259 CAS 0 CAS 1 CAS 2 SP/EN 5 V

Step 5: Output Interface ■ Serial Port Null Modem DTR RTS DSR CTS DCD RXD TXD 16550

STEP 6: How to interface 8255, 8254 & 8259, 16550 ■ Memory mapped/ IO mapped ? ■ Fixed/ Variable addressing ? ■ Address ■ 80 - 86 H -8255 ■ 90 H - 96 H – 8254 ■ A 0 H – A 2 H - 8259 ■ B 0 H - BEH - 16550 ■ Incremental Addressing

A 6 A 5 A 4 I 2 I 1 I 0 O 0 8255 O 1 8254 8259 O 2 LS 138 O 3 M/IO’ 16550 G 2 B G 2 A G 1 A 0 A 7

STEP 7: HOW to Interface Memory ■ How much memory ? ■ ROM/RAM? ■ RAM – minimum 2 k chip- 4 k ■ ROM – minimum 2 k chip – 4 k + 4 k ■ ROM 1 00000 H ■ ROM 2 FF 000 H ■ RAM 01000 H

A 16 A 13 A 12 I 1 I 0 O 0 ROM 1 O 1 RAM LS 138 GND G 2 B O 7 ROM 2 G 2 A G 1 GND A 0 WR’ WRL’ BHE’ WRH’ M/IO’ Memory Decoder

Interface to the processor A 1 A 2 A 0 A 1 CS 8255 RD WR D 0 – D 7 RESET from 8284 RD WR D 0 – D 7 RESET

A 16 -A 19 S 6 -S 3 BHE’/S 7 LS 373 G A 16 -A 19 BHE’ OE’ ALE 8086 AD 8 -AD 15 LS 373 G OE’ A 8 -A 15 AD 0 -AD 7 LS 373 G OE’ A 0 -A 7 MN/MX’ 5 V System Bus of 8086 (Address)

MEMR RD WR LS 244 IO/M OE’ 8086 AD 8 -AD 15 DT/R’ DEN’ AD 0 -AD 7 MN/MX’ IOR D 8 -D 15 OE’ LS 245 DIR MEMW IOW LS 245 DIR LOGIC CIRCUIT D 0 -D 7 OE’ 5 V System Bus of 8086(Data + Control) next

5 V VCC MN/MX 15 M Hz RESET 8284 CLK READY NMI HOLD GND 8086 Inputs

Step 8: Software A B Start Conversion for sensor 16550 send data Main Branch to end of IVT Initialize 8255, 8254, 8259 A Wait for Int N All sensors read Y Wait for 5 min INT ISR 1 ISR 2 SOC (S 1 -S 6) Read ADC IRET B

Step 8: Software - ISR 1 Start Conversion for sensor Enable INT Wait for Int A A N ISR 2 All sensors read Y Send via 16550 IRET Read ADC IRET

Initializing 8255 i 8255: mov al, 10000010 b out 86 H , al

Initializing 8254 i 8254: mov al, 00110110 b out 8 EH , al mov al, 01110101 b out 8 EH , al mov al, 10110101 b out 8 EH , al

Initializing 8254 mov al, 5 out 88 H , al mov al, 0 out 88 H , al mov al, 50 h out 8 AH , al mov al, 0 C 3 h out 8 AH , al mov al, 30 h out 8 CH , al mov al, 75 h out 8 CH , al

Initialising 8259 I 8259: mov al, 1111 1100 b out 90 h, al mov al, 1000 0000 b out 92 h, al mov al, 0000 0011 b out 92 h, al mov al, 1111 1100 b out 92 h, al

16550 Initialization ■ 9600 baud ■ 8 data ■ Odd parity ■ 1 stop ■ SA – F 0 H

16550 initialization LINE LSB MSB FIFO INIT: EQU EQU 0 A 6 H 0 A 0 H 0 A 2 H 0 A 4 H MOV OUT AL, 10001011 B LINE, AL AL, 120 LSB, AL AL, 0 MSB, AL AL, 00001011 B LINE, AL