SHT25 Sensirion I2C Code for Reading Temperature and Humidity—Data Conversion Steps

We wrote code for SHT25 temperature as per the data sheet

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void GetTempAndHumidity(void)
{
U16 DigitalTemp, DigitalHumid;

double TempF,Humidity;

CLEAR_WATCHDOG;
if(ReadTempAndHumid(TEMPERATURE_COMMAND) == CONNECTED_NOT_RESPONDING) // Acquire digital temperature value
{
DataAcq.Temperature.Status = CONNECTED_NOT_RESPONDING;
DataAcq.Humidity.Status = CONNECTED_NOT_RESPONDING;
return;
}
DigitalTemp =( ( ReadValueBuff[0]

i request you to suggest the coding for the above problem.

I use the SHT-21. I don't know if there are any coding differences between that and the SHT-25, but feel free to try my code at "http://arduinotronics.blogspot.com/2010/09/our-temperature-humidity-monitor-is.html(SHT-21)":http://arduinotronics.blogspot.com/2010/09/our-temperature-humidity-monitor-is.html

Could you please send in detail to my mail - kiranbethi(_at_)obelindia.com

please give in details the how the temperature and humidity code written for a resolution of 0.01C

Rther than assume you have a code problem ..... Does the same problem present on more than 1 unit? Are you sure your test system is accurate enough and dwells long enough?

Hi Kiran

The datasheet suggests a 1.8%RH accuracy
It also suggests 8/12 or 14 bit mode depending on the acuracy required

Is this not within specification hence will make no difference to your coding or how you code this

I don’t see the data sheet showing any code

1. Where did you get your code example from?

2. What language are you using

3. What are you setting resolution too?

4. Is the 1.8% specification at 14 bit resolution or 8 resolution?

5. What cpu are you using and what is the clock frequency ?

6. Does your cpu that you are writing the code for utilize pipelining could you provide more explanation if this does

7. What is your instruction time on your cpu ?


8. What is the instruction time total for you to gain such a reading ?

9. Have you considered redoing your code for obtaining temperature in assembler to reduce instruction time overhead?

Reason here is when using a high level language if you go through the assembler listing which is what I would hope you might do You will notice that with high level languages you will see nop, jump to operations, return from operations in your code which implies extra clock cycles that’s extra overhead which could be avoided

Obviously we look for best results but when highly accurate readings are required if using high level languages Clearly you are Its then a good idea to do this in assembler particularly if time is the essence of gaining that result In other words number of instructions



The reason why I am asking these questions is normally on temperature sensors you have to allow a minimum time to obtain such a measurement or if you like to complete its temperature reading cycle before reading back from the cpu

The data sheet also if you read this shows you a very nice chart which explains typical error on the integrated circuit with reference to specific temperatures and suggests continuous cycles as opposed to single cycles


Could you possibly upload this data as requested so that someone can be of guidance to you ?

Thanks

Mark

See figures 1.2 and first paragraph Always a good idea to read the datasheet first before copying code and making purchases I find it works quite well myself

Here are some other examples acc datasheets regards coding and what they suggest for use with the atmel range of processors written in C

They show the complete methods used plus the main method and structures

This is ideally what you want to be posting i.e complete method with above questions answerd then all of us have an idea as to what you are doing with flow charts

Other wise none of us are any the wiser

Example where have you defined TEMPERATURE_COMMAND
or
CONNECTED_NOT_RESPONDING
or
ReadValueBuff[0]

What does your array hold? float, double , int, char
is this signed unsigned 8 bit , 16 bit What ??

How many elements does this hold

Where is your main method ??

Where is your schematic ? ?

I dont know this unless you tell me this

All you tell me is this so far

Quote , " i request you to suggest the coding problems and any changes required in the coding.?"
unquote


DataAcq.Temperature.Status S

o my questions is what is he using C or C++ or another oop langauge perthaps

Nothing else not even a datasheet can we solve this problem and tell him whats wrong

"Hang on ill get my crystal ball out shall I ?"


Not enough info

No im not being funny or rude or insulting at all just to clarify this !! No this is typical !!

hi, thank you for your suggestions.

i am using the C8051F020 controller for my programming.
And i built the complete program as attached.
1) i am founding the problem as follows. instead of 0.01Degree Resolution I am getting a resolution of 0.7Degrees.

2)For Air Relative Humidity - the % of relative humidity exceeeding more than 100%.

help me in finding the solution

I think what you might need to do is get in touch with the manufacturers who make the sensor and ask one of their technical engineers

You still haven’t told me what language you are using for programming?? or answered any of the other questions I’ve asked including a schematic !!

When you do get in touch with the technical engineers They will want these answers from you

So I would if I were in your position, knowing how they work and what they need to know I would get those answers together other wise you will be on the phone for hours , consistently having to go away and gather that information , they don’t liked being mucked about or having to spend hours on the phone dealing with enquiries if you cant get the correct information together to enable them to assist you in the first instance

They’ve got other work to do without all of this

If you have these answers ready then you will find they will be more inclined to assist you and more possibly will be able to tell you’re what are wrong

But unless you do this, very simply put, just as I’m saying, they won’t be able to tell you

So far from your initial question Ive had no datasheets from you , No schematics and what little information I have apart from , you are only getting 0.7 % resolution instead of 0.01% and whats more Ive had to uplaod the datasheets to you which i dare say you havent even bothered to read as yet

How you expect people to assist you with so little information is beyond me In fact how you can write any code what so ever without having all these facts to hand is also beyond me Not even a flow chart of how you might expect this to work

So answers out of 10 , 0 , 0 , 0 ,0 ,0 , 0 ,0 ,0 ,0 And one big fat Zero

In otherwords if this were an assignment You get One BIG FAT ZERO You fail your course work FAIL and thats why your bussineses Fail and your merchandise FAILS and your COUNTRY Fails GOT IT capiche !! Verstaan ​​jy my biae mooi !! , هل تفهم؟ !! , Verstehst du? ,, तुम समझते हो? , Czy rozumiesz? , Вы понимаете? , Anlıyor musun?

Okie cokie !!



You wonder why people get upset Im not suprised

How about you help yourself to help others to help you find a solution Then you might get a better respsonse How about that for you

please find the attachment of sample code available with sensirion from whcih i wrote it for my own controller.
1) I wrote the program using the Silicon 8bit controller - C8051F020
2)Language used - C and compile Keil C51

That’s far better Kiran however its still going to be a problem for one

We don’t have a Kiel too expensive my friend cost to us in GB is some $1200 dollars plus

We are lucky if we can afford £120 .. that’s how hard we are having things at the moment

In fact I looked at some software tonight from Texas Instruments for an IDE plus compiler to seriously start thinking about programming their cpu's and was shocked to find that the price from TI themselves who are normally very good was $5000 us

That’s £2500 UK Thats a years university fees now so when it comes to Kiel I’m afraid its Kiel over and die from shear shock , heart attack , requiring immediate NHS treatment which is well in this case under dear old David Cameron,Tony blair “ Some one assassinate both of them Please “ , you possibly dead anyway but there you go ,

Nothing to be overly concerened about

Unless your name is Lady Thatcher and that means newspaper coverage , best treatment in history whilst the old age pensioners who cant even walk etc have to tolerate exorbitant fees such as £400 for a replacement module for a stair lift which has less components than a state of the art motherboard i5 cpu complete with ddr3 memory at £92.00 Good isn’t it and there you are thinking aaah Britain’s is very wealthy we not me old mackintosh we are to say the least very poor and very badly treated by our marvelous pocket stuffing bonus hierarchy , regardless of the countries futures


TRUE im afraid

Most student’s whishing to undertake studies in this wont be able to afford this that means university students so we can only opt for possibly £300 max

Unfortunately this doesn’t even cover or half cover Microsoft’s development packages example MS studio 2012

Let alone operating systems, let alone office packages, let alone any other development tools that you have to have these days to even start a course, let alone text books, let alone anything else although my government thinks this a complete waste of time and now of course you can see why we have yet another problem with education in the Uk

Only those who can afford this can get the education hence why I am more or less self taught

Answer very simply they don’t invest They don’t believe its necessary We have this argument every year near enough and their answer is also cut costs , cut jobs, and close schools , make teachers redundant , and shaft the whole country That’s my beloved country for you

Now you can see why we get even more annoyed with this pile of doo doo in charge of the country cant you and it doesn’t seem to matter who you put in they are all DOOO doo or Vooo dooo not quite sure at the moment Banks wont lend that type of money in fact they’ve put most of us out of business how they can afford to do this we really don’t know but they seem to think we should just put up with this story In fact we are having a full scale war here with these belisimo's over not just this either Although even the mere likes of me who is this nothing etec plus all the other insults , assaults ripps offs etc etc without trade wars and promises and lies as usual, " I should have joined UB 40 years ago"

This is the attitude that we have in the UK This doesn’t solve your problems but I can see that what you have download and the structure of the examples should work So my immediate assumption would be you have a hardware problem not a software problem if you have applied exactly what theyve instrucetde you to do in the example , then its hardware my friend and many hours of debug the asm with possibly a simulator to see if youve done something funney to assertain possibly instruction time probelms but on the face of things what you have done apperas to be correct so its change the sensor easist way to start

Still best info i can offer at the mo

And you can see the marvelous photo of the control board here costing £400 from a company that wont even come out to investigate the problem because they didn’t install the unit
And two other engineers both of whom have got the diagnosis wrong £40.00 a time You can now again see why we are getting even more annoyed what with no schematics, refusal to supply parts for a couple that desperately need this working Lovely isnt it!!

Old age something to look forward too after many years of hard work and this includes national service for this country as well

Its a pic micro on that one 16C74B not expensive The remote module is half the size of this also pic micro £177.00 there abouts