does this circuit match this code

J

johnlong

Senior Member
Hi All
I am looking at interfacing the 40x2 with a DS1307 and sparkfuns HTU21D breakout board through sparkfuns bi-directional logic level
convertor.
I take no credit for the code which was writen by Marks in another post for the HTU21D that I found on the forum, I mearly altered
the variables used and added a bit of rounding up and down to it and the reading writing to the ds1307.
My main question is in regards to the pullup resistors to the 2 I2cs.
I propose using the pullup resistors on the sparkfun 21d board for the comunication lines with the relivent addresses to the I2c being read.
Will this work or do I have to also put in place the pullup resistors on the 5V side.
proposedHTU21D.jpg

The code is as follows
Code: 
symbol modetop=1  'markers for the diffrent program areas
symbol modemain=2
symbol modevalue=3
symbol modetime=4
symbol modepins=5
symbol modeupdate=6
symbol modeupdate1=7
symbol modeupdate2=8
symbol modeupdate3=9
symbol modertcset=10
symbol modepinset=11
symbol modeset=12
symbol modeprog=13
symbol modework=14
symbol modedelay=15
symbol modeweek=16
symbol modeexchange=17
symbol modewriten=18
symbol modestore=19
symbol modedetermine=20
symbol modefan=21
symbol modehumdry=22
symbol modehumwet=23
symbol modescratch=24
symbol modealarm=25
symbol modereturn=26
'**************************************************************************************
symbol usbon=b1   ' Data storage on or off
symbol pointer=b2  'setpointer and equipment selection in keypad    
symbol marker =b3      'b5 interupt marker between program slots
symbol themode=b4  'program location pointer
'***********************
symbol heaton=b5  'Attached Equipment on or off area obtained via keypad
symbol dehum=b6
symbol humon=b7
symbol air=b8
'*************************************
'TEMPRETURE
symbol vT = b9 	' the preset value for Temperature obtained from keypad
symbol vC=b10   'for setting night tempreture if diffrent tempreture required
symbol NvT=b11    'night tempreture value
symbol Dry=b12    'tempreture value from sensor
symbol Dry1=b13   'tempreture differental used to evaluate outcome
symbol Dry2=b14    'tempreture differental used to evaluate outcome
'**********************************************************
'RHIDITY
symbol ii=b15  'counter used for sensor readings
symbol fr=b16   'Emergancy stop
'*******************************
symbol vHl=b17      '  the preset value for RHidity minimum value via keypad
symbol vH = b18 	' the value maximum for RHidity via keypad
symbol RH=b19      ' RHidity value obtained from sensor
'****************************

symbol TempW = w10	;b21 + b20 used for calculations for all sensors
symbol temp2=w11 'uSD write end b23 +b22
symbol temp_byte=b24 

symbol photo=b25     'light sensor
symbol equip=b26   'On / off times for pins D.3,D.2,D.1,D.0
symbol volt=b27   'Fan speed 
symbol line=b28  'VARIABLES FOR uSD for line feed in excel
   

'*********************************************************************************************
'SETTING VARIABLES FOR DS1307 
symbol datebcd=b29
symbol monthbcd=b30
symbol yearbcd=b31  'Variables from keypad converted at SetRTC to BCD
symbol daybcd=b32    'Loaded into the DS1307
symbol hourbcd=b33
symbol minbcd=b34
symbol secbcd=b35
'******************************************************************
'PICAXE VARIABLES FOR CONVERTED VALUES FROM I2C CLOCK
symbol sec =b36
symbol hour=b37
symbol mins=b38  'Read back variables from the DS1307 using the DS1307 as the
symbol day=b39   'Timer for the Data Logging and Display
symbol month=b40  'hour = hourbcd / 16 * $FA + hourbcd Hippy's solution for BCD to Dec conversion
symbol year=b41
symbol date=b42
'********************************************************************************
symbol Tdry=w23 symbol TEMPmsb=b47 symbol TEMPlsb=b46
symbol Hum=w24   symbol RHmsb=b49 symbol RHlsb=b48


SYMBOL Sign = b50

'**********************
symbol TD4=b33
symbol TD3=b32
symbol TD2=b31
symbol TD1=b30
symbol TD0=b29
symbol control=$10 ' sets RTC 

symbol hi2c =C.3 ' 40x2 pin conection for DS1307 and HTU21D
   





#picaxe 40x2
	hi2csetup i2cmaster, %11010000, i2cslow_8, i2cbyte
	
  	
  		hi2cin 0, (secbcd,minbcd,hourbcd)    'READ RTC       		  
         		 hour = hourbcd / 16 * $FA + hourbcd
    		 mins = minbcd / 16 * $FA + minbcd
      		  sec = secbcd / 16 * $FA + secbcd
  		pause 500
main:			 
	do
		
	hi2csetup i2cmaster, %11010000, i2cslow_8, i2cbyte 
  	
     		do
		hi2cin 0, (secbcd,minbcd,hourbcd)    'READ RTC       		  
         		 hour = hourbcd / 16 * $FA + hourbcd
      		 mins = minbcd / 16 * $FA + minbcd
      		  sec = secbcd / 16 * $FA + secbcd
		
    		pause 800
		peek 80,@bptr
 		loop until mins<>@bptr

hi2csetup i2cmaster,0x80,i2cslow_8,i2cbyte ' %10000000 (hex 0x80) is device i2c bus address
Pause 20
hi2cin 0xE3, (TEMPmsb,TEMPLsb) : TEMPLsb = TEMPLsb AND 0xFC ' Last bits of LSBdata ,
Pause 20
hi2cin 0xE5, (RHmsb ,RHlsb ) : RHlsb = RHlsb AND 0xFC ' must beset to ?0? before calculating
pause 20

Calculate_Temp: ; TempActual = TempSensor /65536 x175.72 -46.85
Tdry = Tdry **17572 -4685 ' -40.00 to 125?C 14bit
Sign = " " ' Display +
IF Tdry > 13000 THEN 
Sign = "-" ' Display -
Tdry = -Tdry
ENDIF
BinTOASCII Tdry,TD4,TD3,TD2,TD1,TD0
IF TD4 = "0" THEN : TD4 = " " ' leading zero blanking
IF TD3 = "0" THEN : TD3 = " " : ENDIF ' leading zero blanking
ENDIF
'sertxd ( " Temperature ",Sign,TD4,TD3,TD2,".",TD1,TD0,"?C",cr,lf)
dry= TD3-48*10
dry=dry+TD2-48
TD0=TD0-48
TD1=TD1-48
if TD0>=5 then
TD1=TD1+1
endif
if TD1>=5 then
dry=dry+1
endif
'sertxd ("DRY=",32,#dry,cr,lf)  

RH_Compensated:
Tdry =Tdry /10 ; RHcompensated = RHactual + (25 -TempActual) x -0.1
IF Sign = "-" THEN : Tdry = -Tdry : ENDIF ' improves RHaccuracy over 0.00 to 80.00?C


Calculate_RH: ; RHactual = RHsensor /65536 x125 -6
Hum = Hum **12500 -600 + Tdry -250 ' -6.00 to 118 Rh% 12bit
Sign = " " ' Display +
IF Hum > 13000 THEN
Sign = "-" ' Display -
Hum = -Hum 
ENDIF 

BinTOASCII Hum,TD4,TD3,TD2,TD1,TD0
IF TD4 = "0" THEN : TD4 = " " ' leading zero blanking
IF TD3 = "0" THEN : TD3 = " " : ENDIF ' leading zero blanking
ENDIF
'sertxd ( " RHcompensated ",sign,TD4,TD3,TD2,".",TD1,TD0,"%",cr,LF)
RH=TD3-48*10
RH=RH+TD2-48
TD0=TD0-48
TD1=TD1-48
if TD0>=5 then
TD1=TD1+1
endif
if TD1>=5 then
RH=RH+1
endif
sertxd(#hour,32,":",#mins,cr,lf)
sertxd ("DRY=",32,#dry,"C",32,"HUMIDITY=",32,#RH,"%",cr,lf)
poke 80,mins
'for b0=0 to 10
 'Pause 2000
'next b0
loop
regards
john
 
I

inglewoodpete

Senior Member
johnlong said:
My main question is in regards to the pullup resistors to the 2 I2cs.
I propose using the pullup resistors on the sparkfun 21d board for the comunication lines with the relivent addresses to the I2c being read.
Will this work or do I have to also put in place the pullup resistors on the 5V side.
Click to expand...
lbenson said:
You still need pullups on the 5V side.
Click to expand...
As you say, the Sparkfun level converter board has 10k pullups on either side of the FET.

10k should be sufficient but may need reducing to 4.7k if i2c bus lengths are over half a metre or so. Try it and see what the results are like.

If you need to reduce the value of the existing pullup(s) to ~4,7k, and if you have a steady hand, you can just solder a second 10k resistor on top of the existing one(s) on the level-shifter board.
 
J

johnlong

Senior Member
Thanks for that
not to sure about the steady hand bit, poggy finger syndrome coupled with squint eye.
Looking at a final length of around 3 metres from sensor to main board.
Have run a bread board test at this length( using cat5) with all parts at 3.3v using salts to obtain the expected RH with good results
But need 5v for the lcd. Maybe an idea to run the picaxe at 3.3v and level converter to the lcd side of things?
your comments on this aproach would be most welcome
regards
john
 
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