We are having a little trouble testing the temperature sensor v1.1 The sensor is showing a raw value of about 980 for room temperature, which seems to agree with the value shown on the monitor in the picture to the right of the Try it out section just below the code. The values shown in the monitor convert this to a value of about 20C. But the converted value we get is 0C/32F, which is the overflow value. We are using the RRRF supplied thermistor, and when measured with an ohm meter it has a resistance of about 100K, so it looks like we have have the right value. Looking at the code I am not sure I understand what it is doing. The first column is marked adc, but it contains values between 0 and 300 which sounds like a temperature range. The other column goes up to from 1 to 680. Neither of these values go up to 980. So was the picture generated with a different thermistor? Anyone got any clues? David https://reprap.org/forum/read.php?13,16120,16120#msg-16120 Tue, 08 Sep 2026 17:59:17 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?13,16120,20910#msg-20910 https://reprap.org/forum/read.php?13,16120,20910#msg-20910
I had some trouble with my thermistor because I bought one from a local hardware store (Brazil) and it's different from those listed on the thermistor page. It had a lower beta value and Nophread's python scrypt did not calculate the correct converstion matrix. Obviously it got the temperature all wrong.

So I decided to start from scratch (almost) :-) and made a few changes to the thermistor test source code. In the end I believe the compiled code is smaller because I eliminated the celcius column in the matrix and kept only the rawdata. To do this, I made the table in a way that the celcius temperature is incremented in 25 degree steps, so I can simply increment the celcius variable in 25 every loop.

I made a spreadsheet to help me (and hopefully others) calculate the Beta, Rz, and the conversion matrix for any thermistor.

The spreadsheet and the thermistor test sourcecode are available at my RepRap journal:
[journals.fotki.com]

Regards,
Rod]]> rora Controllers Wed, 28 Jan 2009 15:19:13 -0500 https://reprap.org/forum/read.php?13,16120,16301#msg-16301 https://reprap.org/forum/read.php?13,16120,16301#msg-16301
sorry about that. as pjr pointed out, the table in the example was wrong. i fixed the code in the wiki.

~Zach]]> ZachHoeken Controllers Fri, 29 Aug 2008 10:10:24 -0400 https://reprap.org/forum/read.php?13,16120,16298#msg-16298 https://reprap.org/forum/read.php?13,16120,16298#msg-16298
David]]> davidgoodenough Controllers Fri, 29 Aug 2008 09:41:27 -0400 https://reprap.org/forum/read.php?13,16120,16292#msg-16292 https://reprap.org/forum/read.php?13,16120,16292#msg-16292
You need to cut and paste the one for the Epcos device if you are tesing one of the current RRRF kits ... there is a link on the make page to the RepRap thermistor page which has several tables.

Peter]]> pjr Controllers Fri, 29 Aug 2008 08:35:08 -0400 https://reprap.org/forum/read.php?13,16120,16133#msg-16133 https://reprap.org/forum/read.php?13,16120,16133#msg-16133
David]]> davidgoodenough Controllers Mon, 25 Aug 2008 18:06:52 -0400 https://reprap.org/forum/read.php?13,16120,16129#msg-16129 https://reprap.org/forum/read.php?13,16120,16129#msg-16129 reprap.org] (assuming you're using arduino electronics)?

Also, [hydraraptor.blogspot.com] might be useful, though I haven't peered at it closely enough to tell ;)]]> Ru Controllers Mon, 25 Aug 2008 15:40:06 -0400 https://reprap.org/forum/read.php?13,16120,16120#msg-16120 https://reprap.org/forum/read.php?13,16120,16120#msg-16120
The sensor is showing a raw value of about 980 for room temperature, which seems to agree with the value shown on the monitor in the picture to the right of the Try it out section just below the code. The values shown in the monitor convert this to a value of about 20C.

But the converted value we get is 0C/32F, which is the overflow value.

We are using the RRRF supplied thermistor, and when measured with an ohm meter it has a resistance of about 100K, so it looks like we have have the right value.

Looking at the code I am not sure I understand what it is doing. The first column is marked adc, but it contains values between 0 and 300 which sounds like a temperature range. The other column goes up to from 1 to 680. Neither of these values go up to 980.

So was the picture generated with a different thermistor?

Anyone got any clues?

David]]> davidgoodenough Controllers Mon, 25 Aug 2008 11:28:09 -0400