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by James26
Tue Sep 10, 2013 10:41 am
Forum: Automation, sensing and robotics
Topic: Op amp saturation
Replies: 2
Views: 809

Op amp saturation

Hi all, I have now got my thermcouple sensing datalogger working, I have thermocouple connected to compensator and amplifier circuit, then I connect this to a level shifter in order to bring the voltages posotive and between 0 -3.3v so I dont blow up my Pi :geek: I have a thermal chamber which I can...
by James26
Wed Sep 04, 2013 9:33 am
Forum: Automation, sensing and robotics
Topic: Thermocouple amplifier and level shifter
Replies: 2
Views: 872

Re: Thermocouple amplifier and level shifter

anyone able to help ? thanks
by James26
Tue Sep 03, 2013 1:12 pm
Forum: Automation, sensing and robotics
Topic: Thermocouple amplifier and level shifter
Replies: 2
Views: 872

Thermocouple amplifier and level shifter

Hi there, I have wired up a type t thermocouple to an LTK001 (amplifier/compensator) using the diagram given on the data sheet shown to give 10mv/deg C. Since this runs from a +5v / -5v supply i then step down this voltage from 10v pp to 3.3v using a level shift which has a reference voltage of 1.65...
by James26
Wed Aug 28, 2013 7:42 am
Forum: Automation, sensing and robotics
Topic: Thermocouple data logger
Replies: 5
Views: 4436

Re: Thermocouple data logger

Sorry dont think I explained very well, This is a project I have been given and due to certain requirements for it I am only allowed to use a type T thermocouple therefore I can't use the MAX amplifiers. I have my circuit wired up http://www.google.co.uk/imgres?q=ltk001+application&um=1&safe...
by James26
Tue Aug 27, 2013 7:36 am
Forum: Automation, sensing and robotics
Topic: Thermocouple data logger
Replies: 5
Views: 4436

Thermocouple data logger

Hi there, I have been working on a project to read temperature from a thermocouple using a Gertboard/Rpi. I have a code written in C which I have tested using function generator to ensure its operation and it does work as I expect. I have been using LTK001 which is a cold junction compensator and ma...
by James26
Thu Aug 22, 2013 11:19 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

Thanks alot, got it working.
Appreciate your help
by James26
Thu Aug 22, 2013 10:37 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

EDIT: my bad, I entered the cronjob wrong. I get nothing in the output file but in the error file I get this: rm : cannot remove 'log.txt.7': no such file or directory mv: cannot stat: 'log.txt.6': No such file or directory mv: cannot stat: 'log.txt.5': No such file or directory mv: cannot stat: 'lo...
by James26
Thu Aug 22, 2013 9:08 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

As far as crontab is concerned - have you looked at the syslog when it is supposed to run? Did you add the redirections to crontab to create the output and error output log files? What did the syslog file say? What did the log files contain? They should give a clue as to what is going wrong. Cheers...
by James26
Thu Aug 22, 2013 7:19 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

so can changing the time/date cause problems when trying to run code ? Just wondering, As I am now currently seeing: make: Warning: File 'atod' has modification time 2.9e+05 s in the future make: 'atod' is up to date. make: warning: Clock skew detected. Your build may be incomplete. When I try and c...
by James26
Wed Aug 21, 2013 1:58 pm
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

hmm, ive tried both methods mentioned but still no luck. I have also made sure cron was enabled and so dont understand why the cron does not work ? even though the code works independently
by James26
Wed Aug 21, 2013 8:51 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

I have wrote my bash script (.sh file) and when I run it alone it works. but when I change the time to 23:59 and await the crontab to execute the bash file itself it does not work ? in the crontab I have opened it using crontab -e and entered the line: @daily /home/pi/gertboard_sw/myscript.sh any id...
by James26
Tue Aug 20, 2013 2:05 pm
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

joan wrote:It's possibly simpler if you just call a script in your home directory from cron, e.g.

Code: Select all

@daily              /home/pi/myscript
Remember to make the script executable, i.e.

chmod +x /home/pi/myscript
so what kind of file is myscript ?
by James26
Tue Aug 20, 2013 1:19 pm
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

okay, so i understand that i open crontab and write the jobs to perform in here. If I write @daily<command1> then this should perform command 1 at midnight everynight for me, right ? But I'm still confused about "command1" do I write a seperate file for this or do I just stick in the code ...
by James26
Tue Aug 20, 2013 11:15 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

You could then write a small script that runs as a cronjob at midnight every day and does something like: rm temp.log.7 mv temp.log.6 temp.log.7 mv temp.log.5 temp.log.6 ... mv temp.log.1.temp.log.2 mv temp.log temp.log.1 which would keep the last 7 days results as temp.log.1 to temp.log.7 (though ...
by James26
Mon Aug 19, 2013 8:44 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

Simplest solution would be do something like: printf("the voltage is: %f the temp is: %f\n", voltage, temp); log = fopen("temp.log", "a"); fprintf(log, "%f,%f\n", voltage, temp); fclose(log); This would open a file (temp.log) for writing at the end of file (a...
by James26
Mon Aug 19, 2013 8:06 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

It depends a lot on what you want to do with the data later. Is it going to be processed automatically? Does it need to be human readable? Are you going to import it into a spreadsheet? Just a few ideas: You could write it into a CSV (comma separated variable) file - which is human readable and can...
by James26
Mon Aug 19, 2013 7:16 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

10^-3 is 1e-3, not 10e-3. 43*10^-3 is probably best written as 43e-3. Yep, mea culpa. Hi James26, So are you asking how to save your data to a file? Do you need the date and time of the reading logged too? Can you give us a little more information about what you want to achieve? Hi, Yeah, i think t...
by James26
Wed Aug 14, 2013 2:13 pm
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

As mentioned I am trying to use a thermocouple, I have also been told I need to have the ability to store data for a period of 7 days...
How to I store my data automatically from each sample ?
by James26
Tue Aug 13, 2013 1:22 pm
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

The code I added in does not return any results when running the code ... I assume you mean it prints 0.0000 for both voltage and temperature. Is that correct? You actually aren't using any of the functionality out of the math.h file. When you include math.h you get to use function like sin, cos, t...
by James26
Tue Aug 13, 2013 11:46 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

Re: C math library for Pi?

Here is what I added in: (Apologies, cant copy and paste directly from my code as my work will not let me connect Pi to the network) voltage = (v / 1024) * 3.3; // v - number of bits read temp = voltage / (43*10^-3); printf(" the voltage is: %f the temp is: %f", voltage, temp); This was ad...
by James26
Tue Aug 13, 2013 11:13 am
Forum: C/C++
Topic: C math library for Pi?
Replies: 33
Views: 6154

C math library for Pi?

Been attempting to change some code on the gertboard to convert the output of bits into a temperature read from a thermocouple. The code I added in does not return any results when running the code although it compiles with no problem. I had been adding in the library math.h but I am unsure if this ...
by James26
Mon Jul 22, 2013 3:40 pm
Forum: Beginners
Topic: Max31855 c drivers ?
Replies: 1
Views: 615

Max31855 c drivers ?

Hi, Only just started using the raspberry pi and very new to programming, I have been given a project from my work to record temerature and store data over the period of 7 days. For now I am just experimenting with thermocouples and the MAX31855 amp, so the question I am asking is... Is there any dr...

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