'DATDS08M.BAS = temp.datalogger-Picaxe-08M variation Ver 1.00  30/9/04   Stan. SWAN
'NB-this enhances orig. 08 version as the new 08M "sertxd" cmd feeds serial data out 
'"18X style" via progr. lead @ 4800bps & displays via editors F8/F9 inbuilt terminal.
'Options->Options->auto open serial terminal after download gives instant F8 display
'But-Grr!- F9 5 sec time out prevents live data display.Use StampPlot instead maybe ?
'===================================================================================
'Use with DS18B20 temp sensor IC etc to Picaxe-08M Ch.1. Via=> s.t.swan@massey.ac.nz
'DS18B20 reads -10C to +85C to +/- 0.5C,but wider with less accuracy. Supply 3-5.5V 
'N.B.Subzero "bug"-temps <0 C read as ascending from 128. Ex 129 = -1C, 130 = -2C etc
'Fix when >127 by subtracting 128.Thus b1=b1-128  Ex.-3= 131-128. (Ref Cmd HELP P.66)
'Insuffient memory left on 08M to implement ! 18X has much greater RAM so handles OK
'Program inspired by lo res NTC data08M.bas -an upgrade of Sept.'03 SiChip 08 version 
'When "08M" powered up,any prior stored EEPROM values sent as SERTXD serial port data 
'-suit 4800bps display via any terminal program -LCD,F8,StampPlot- or.csv Excel too.
'NB-Gives you 30secs to turn unit OFF before fresh storage begins & thus progressively
'wiping existing values ! For security however this data can't easily be bulk erased
'***BUT CARE - BE PROMPT ! REPROGRAMMING/RELOADING  "08M" TOTALLY WIPES DATA TOO ****.
'As set up logs direct Celsius temp every 60 secs for ~2 hrs. Alter WAIT value to suit?
'A further tempting enhancement uses DS 1307 clock chip  for improved logging times
' -sold as 4 channel Rev.Ed 18X datalogging PCB kit with extra I2C memory in fact.
'-------------------------------------------------------------------------------------
'PICAXE08M has hi-res data values 0-255(via "readadc" command),but also READTEMP for
'direct DS18B20 Celsius readings! Values stored in program space (like "08")- care !
'"Data compression" scope that'll maybe give 256 values ? 18X + I2C better if pushed 
'If power saving needed use SLEEP instead of WAIT ex. 25x2.3secs ~1min delay (+/- 1% )
'Alter to suit.Ex.Sleep 391 =128x1/4 hr =32hrs run.Some interpreter o'head/drift noted
'128 readings,so @ 1/min ~2 hrs, /5 min ~10 hrs, /30 min ~2.5 days,& /60 min ~5 days  
'NB- sensor thermal lag means there's little point sampling faster than every minute ! 
'Solderless "PICNIK" breadboard setup pix => www.picaxe.orcon.net.nz/datds08m.jpg 
'Sample Excel graph resulting (1 hour runon 18A)=> www.picaxe.orcon.net.nz/datads18.gif
'Program hosted=> www.picaxe.orcon.net.nz/datds08m.bas  & circuit=> ... /datds08m.gif 
'--------------------------------------------------------------------------------------
'  SERTXD					           	DS18B20 pinouts
' & piezo              - - - - - - - - - - - - -ve rail           (top view)
'   Ch.0     _____   Ch. |          |		    
'    - |    ___  |   2  LED         |		                      * *
'    ------    | |_______|          |		                    *     *
'   |Picaxe|   |_________           DS18B20                        *       *
'   | 08M  |       Ch.1  |_____________|  | 		           *       *
'    ------    (READTEMP)      |          |                        ---------
'    +          	      4.7k        |                       /   /   /
'|||	                       |          | 		         /   /   /
'Usual 3 wire         + + + + + + + + + + + +ve supply          0V  |   V+
'prog.input                                (3-5V ~10mA)            data
'---------------------------------------------------------------------------------------
					'READ/PLAYBACK ROUTINE 
pause 100				'needed to wake up sertxd & avoid initial junk?
sertxd(" PICAXE-08M DS18B20 Temp.Datalogger",13,10)		' Title header 
for b0=0 to 127				'stored data values readout to terminal or LCD
read b0,b1				'polls & reads out stored eeprom values ( .csv)
sertxd(#b0,44,#b1,13,10) 		'Actual value @ prog.pin,+ comma for Excel .csv
next b0					'read next stored EEPROM value & SERTXD out 
wait 30					'30 secs "reading" delay -modify if too short etc
'----------------------------------------------------------------------------------------
					'WRITE/DATA LOGGING ROUTINE
for b0= 0 to 127			'begin 128 data readings @ time set by SLEEP/WAIT
sound 0,(75,10)		    		'Beep to alert data logging commencing
pulsout 2,500				'brief flash from pin 2 LED indicates datalogging
readtemp 1,b1				'direct Celsius reading of DS18B20 temp. returned 
sertxd(#b0,44,#b1,13,10)		'Now allows data display (via F8 )as gathered too !
write b0,b1 				'sequentially write values to EEPROM locations
wait 60 				'Checks every 60 secs (max 65)-alter to suit etc	
next b0					'Gathering automatically stops after 128 samples
high 2					'Ch.2 green LED on to show data run ended (optional)
'----------------------------------------------------------------------------------------