The Old Solar Sensor

This device measures local temperature, humidity, and solar intensity. It was used for several years until it failed due to copper dendrites formed where circuit traces were in contact with wood. It was replaced by the Solar Sensor which is included in the Weather System.

It is described here because it was repaired and still exists. Its problem was because it gets its power from a solar panel on its top, so it must be put in a sunny place.

This not only caused the wooden housing to get wet and rot, but it increased the temperature reading,

Temperature and humidity are measured by a Sensirion SHT15 digital module. These and battery voltage were transmitted in a 4-byte message.

By comparison, its replacement has a remote solar array, adds pressure sensing, and is in a hermetically-sealed plastic case.

Old Solar Sensor Picaxe Program

Declarations and Data

This is housed in a box for outside use. A 5-cell rechargeable battery is charged by a solar panel.

Battery voltage, charging current, temperature and humidity are measured.

Temperature and humidity are measured by a Sensirion SHT15 digital module.

The measurements are transmitted on 434 MHz using a Wenshing TWS-BS module

John Saunders 3/13/2017 added checksum;new humidity calculation.10/8/2018 output padded

#endrem

#picaxe 18X

rem Inputs

symbol SHTIn = pin6

symbol I_In = 1

symbol V_In = 0

rem Outputs

symbol SHTCLK = 6

symbol SHTOut = 7

symbol TxOut = 5

symbol Monitor = 0

rem Global variables

symbol SHTACK = bit0 '0=the SHT accepted the command

symbol SHTVal = bit1 'State of the output bit from the SHT

symbol MeasID = b1 'What to measure: 0=humidity, 1=temperature,2-current,3=voltage

symbol Phase = b2 'The main loop is divided into 10 phases

symbol Err_Cnt = bit2

rem General variables

symbol InByte = b3

symbol VarAddr = b4

symbol Hunds = b5

symbol Units = b6

symbol Tens = b7

symbol Mask = b8

symbol Char = b9

symbol InWord = w6

symbol Scratch = w5

rem EEPROM

DATA 0,(128,64,32,16,8,4,2,1)

DATA 10,( 0, 0, 1, 1, 2, 4, 5, 6, 7, 8)

DATA 20,( 9,10,11,12,14,15,16,17,18,19)

DATA 30,(20,21,22,23,24,25,26,28,29,30)

DATA 40,(31,32,33,34,35,36,37,38,30,40)

DATA 50,(41,42,43,44,45,46,47,48,49,50)

DATA 60,(51,52,53,54,55,56,57,58,59,60)

DATA 70,(61,62,63,64,64,65,66,67,68,69)

DATA 80,(70,71,72,73,74,75,76,76,77,78)

DATA 90,(79,80,81,82,83,84,84,85,86,87)

DATA 100,(88,89,90,90,91,92,93,94,95,96)

DATA 110,(96,97,98,99,100)

rem Constants

symbol Pulseval = 20

symbol SHTPeriod = 5400

symbol SHTGap = 560

symbol StartAddr = 80

symbol MinOKVolt = 140

Init and Main

init:

SETFREQ m8

LOW SHTCLK

LOW TxOut

LOW SHTOut

LET Phase = 0

SLEEP 1

FOR Char = 0 TO 9

PULSOUT SHTClK,Pulseval

NEXT Char

LET Err_Cnt = 0

LOW Monitor

main:

LOOKUP Phase,(3,2,0,2,3,2,1,2,3,2,3,3,2,0,2,3,2,1,2,3,2,3),MeasID

LET VarAddr = 2 * MeasID + StartAddr

SELECT MeasID

CASE 0,1 'SHT

GOSUB SHTCommand

IF SHTACK = 0 THEN

GOSUB SHTWait

GOSUB SHTMeas

LET char = VarAddr + 1

POKE char,InByte

HIGH SHTOut

PULSOUT SHTCLK,Pulseval

GOSUB SHTMeas

POKE VarAddr,InByte

ELSE

LET Err_Cnt = 1

ENDIF

CASE 2 'Solar charging current

READADC I_in,InByte

LET InByte = 256 - InByte

PEEK VarAddr,WORD InWord

LET InWord = InWord + InByte

POKE VarAddr,WORD InWord

CASE 3

READADC V_In,InByte

IF InByte < MinOKVolt THEN init 'Out of regulation

PEEK VarAddr,WORD InWord

LET InWord = InWord + InByte

POKE VarAddr,WORD InWord

ELSE

LET InWord = 0

ENDSELECT

PAUSE SHTPeriod

INC Phase

IF Phase > 21 THEN

LET Phase = 0

GOSUB WriteOut

FOR Char = 4 TO 7 ;Current and voltage

LET VarAddr = StartAddr + Char

POKE VarAddr,0

IF Err_Cnt = 1 THEN init

ENDIF

GOTO main

Sub-programs

SHTCommand: 'SHTCmd is 1 for Humidity, 0 for temperature

rem SHT Start:

HIGH SHTCLK

HIGH SHTOut

LOW SHTCLK

HIGH SHTCLK

LOW SHTOut

LOW SHTCLK

HIGH SHTOut

PAUSE 1

rem SHT Command

IF MeasID = 1 THEN

LET Scratch = 5 'Humidity

ELSE

LET Scratch = 3 'Temperature

ENDIF

FOR Char = 0 TO 7

READ Char,Mask

LET InByte = Scratch & Mask

IF Inbyte = 0 THEN

HIGH SHTOut

ELSE

LOW SHTOut

ENDIF

PULSOUT SHTCLK,Pulseval

NEXT Char

LET SHTACK = SHTIn 'If 0 ack is OK

PULSOUT SHTCLK, Pulseval

LOW SHTOut

RETURN

SHTMeas:

LET InByte = 0

LOW SHTCLK

LOW SHTOut

FOR Char = 0 TO 7

READ Char,Mask

LET SHTVal = SHTIn

IF SHTVal = 1 THEN

LET InByte = InByte + Mask

ENDIF

PULSOUT SHTCLK,Pulseval

NEXT Char

RETURN

WriteOut: '216 ms

LET Char = 132 '3 commas

HIGH TxOut

PAUSE 40

LOW TxOut

PAUSE 20

SEROUT TxOut,N2400_8,("14L1776s,K,") 'K is code for 15

FOR MeasID = 0 TO 3

LET Mask = 2 * MeasID + StartAddr

PEEK Mask, WORD InWord

IF MeasID = 0 THEN 'Temperature

IF InWord > 0 THEN

LET InWord = InWord/10

LET InWord = 9 * InWord

LET InWord = InWord - 1978

LET Scratch = InWord/50

ELSE

LET Scratch = 32

ENDIF

IF MeasID = 1 THEN 'Humidity

LET VarAddr = InWord/31 + 10

IF VarAddr > 114 THEN

LET Scratch = 100

ELSE

READ VarAddr,Scratch

ENDIF

IF MeasID = 2 THEN 'Current

LET Scratch = InWord/20

ENDIF

IF MeasID = 3 THEN 'Battery Voltage

LET Scratch = InWord/2

ENDIF

LET Hunds = Scratch/100 + 48

LET InByte = Scratch // 100

LET Tens = InByte /10 + "0"

LET Units = InByte // 10 + 48

LET Char = Char + Hunds + Tens + Units

SEROUT TxOut,N2400_8,(Hunds,Tens,Units,",")

'SERTXD (Hunds,Tens,Units,",")

LET InByte = Char / 16

IF InByte < 10 THEN

LET Tens = InByte + "0"

ELSE

LET Tens = InByte + "7"

ENDIF

LET InByte = Char & $0F

IF InByte < 10 THEN

LET Units = InByte + "0"

ELSE

LET Units = InByte + "7"

ENDIF

'SEROUT TxOut,N2400_8,(Tens,Units,13,10)

SEROUT TxOut,N2400_8,(Tens,Units,13,10,4,4,4,4,4,4) 'Padding added 10/8/2018

'SERTXD (Tens,Units,13,10,4,4,4,4,4,4)

RETURN

SHTWait: '68 & 244 ms

LET Char = 0

INC Char

LET SHTACK = SHTIn 'If 0 measurement is done

PAUSE 1

LOOP WHILE Char < SHTGap AND SHTACK = 1

RETURN