Comments on: Using the MAX6675 Thermocouple-to-Digital Converter http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/ Andrew's Project Blog - hardware, software, things Tue, 31 Aug 2010 07:51:52 +0100 http://wordpress.org/?v=2.9.2 hourly 1 By: Ryan http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-141 Ryan Wed, 28 Apr 2010 21:55:56 +0000 http://www.rocketnumbernine.com/?p=287#comment-141 The connectors are really nice, esp because they make the system "proper" for thermocouples. (Memories of engineers yelling at me at work for using dissimilar metals for hooking thermocouples, ahhh!) The cost kinda sucks, but its worth it after the number of boards I fried trying to attach/solder thermocouple wire. The connectors are really nice, esp because they make the system “proper” for thermocouples. (Memories of engineers yelling at me at work for using dissimilar metals for hooking thermocouples, ahhh!) The cost kinda sucks, but its worth it after the number of boards I fried trying to attach/solder thermocouple wire.

]]> By: andrew http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-140 andrew Wed, 28 Apr 2010 19:47:04 +0000 http://www.rocketnumbernine.com/?p=287#comment-140 I've talked to the MAX665 using the SPI library on both an Arduino and an AT90USB running on a Teensy board, sketch is 3172 bytes on the Arduino (although 2K of that is the Serial and print) Those Thermocouple connectors look great! - haven't seen them before, have been using 0.1" header sockets which isn't ideal for the thin thermocouple wire. I’ve talked to the MAX665 using the SPI library on both an Arduino and an AT90USB running on a Teensy board, sketch is 3172 bytes on the Arduino (although 2K of that is the Serial and print)
Those Thermocouple connectors look great! – haven’t seen them before, have been using 0.1″ header sockets which isn’t ideal for the thin thermocouple wire.

]]> By: Ryan http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-138 Ryan Wed, 28 Apr 2010 01:00:52 +0000 http://www.rocketnumbernine.com/?p=287#comment-138 Great article. What is the final sketch size? I created my own library for the MAX6675 (http://code.google.com/p/max6675-arduino-library/) when I needed to interface the chip for temp monitoring on my reflow and outdoor grill. It worked well, but I still need to do a few updates on the library. I didn't want to get involved with the SPI library at the time, but you make it seem simple. BTW, for the breakouts I made I used a PCB thermocoupe connector which makes a real good connection for the thermocouple and doesn't give error in the readings. Great article. What is the final sketch size?

I created my own library for the MAX6675 (http://code.google.com/p/max6675-arduino-library/) when I needed to interface the chip for temp monitoring on my reflow and outdoor grill. It worked well, but I still need to do a few updates on the library. I didn’t want to get involved with the SPI library at the time, but you make it seem simple.

BTW, for the breakouts I made I used a PCB thermocoupe connector which makes a real good connection for the thermocouple and doesn’t give error in the readings.

]]> By: andrew http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-62 andrew Fri, 09 Oct 2009 06:36:32 +0000 http://www.rocketnumbernine.com/?p=287#comment-62 Its fairly trivial c code that should work. The only issue is that you need to define the pins the the ATMega328p uses for SPI. From www.atmel.com/dyn/resources/prod_documents/doc8011.pdf, it looks like it should be something like the following: elif defined(__AVR_ATmega324p__) #define SPI_SS_PIN PB4 #define SPI_SCK_PIN PB7 #define SPI_MOSI_PIN PB5 #define SPI_MISO_PIN PB6 Its fairly trivial c code that should work. The only issue is that you need to define the pins the the ATMega328p uses for SPI.
From http://www.atmel.com/dyn/resources/prod_documents/doc8011.pdf, it looks like it should be something like the following:

elif defined(__AVR_ATmega324p__)
#define SPI_SS_PIN PB4
#define SPI_SCK_PIN PB7
#define SPI_MOSI_PIN PB5
#define SPI_MISO_PIN PB6

]]> By: Devin http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-61 Devin Thu, 08 Oct 2009 23:10:55 +0000 http://www.rocketnumbernine.com/?p=287#comment-61 Andrew, Will the SPI header you included work run out of the box for example with a AtMega324p? The code looks like standard C code and something that I could use in AVR Studio but having never used SPI before I am little apprehensive. Any help would be awesome. Andrew, Will the SPI header you included work run out of the box for example with a AtMega324p? The code looks like standard C code and something that I could use in AVR Studio but having never used SPI before I am little apprehensive. Any help would be awesome.

]]> By: andrew http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-43 andrew Thu, 23 Jul 2009 20:11:22 +0000 http://www.rocketnumbernine.com/?p=287#comment-43 The SPI helper library works on the Teensy. If your happy using GCC with the AVR then all that's required is to replace the Arduino code (print/pinMode/digitalWrite etc.) with GCC/prjc library calls and place everything in a main function. I'd suggest changing the PRJC blinky test application. The hid_listen program (downloadable from the <a href="http://www.prjc.com/" rel="nofollow">PRJC website</a> can be used to listen to the text sent from the Teensy. The Teensy Arduino plugin might allow you to run the arduino code as is on the Teensy - but i haven't tried that. I designed a break out board with Eagle and ordered through <a href="http://www.batchpcb.com/product_info.php?products_id=20538&check=1586acac99a545c865a8a0ae59868ddc" rel="nofollow">BatchPCB</a> that allows the SOIC-8 IC package to be plugged in to a bread board (I added a photo to the top of the blog), these can also be bought from <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=494" rel="nofollow">sparkfun</a> (I think it works out cheaper to buy from sparkfun if ordering something else than using batchpcb due to the small size of the board). It's not the easiest thing to solder but is just about manageable it with a thin solder bit (search youtube for lots of SMD soldering tutorials). This can be used on a prototype board with the Teensy or even a <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=7914" rel="nofollow">prototype shield</a> on top of the Arduino. Hope this helps, good luck The SPI helper library works on the Teensy. If your happy using GCC with the AVR then all that’s required is to replace the Arduino code (print/pinMode/digitalWrite etc.) with GCC/prjc library calls and place everything in a main function. I’d suggest changing the PRJC blinky test application. The hid_listen program (downloadable from the PRJC website can be used to listen to the text sent from the Teensy. The Teensy Arduino plugin might allow you to run the arduino code as is on the Teensy – but i haven’t tried that.

I designed a break out board with Eagle and ordered through BatchPCB that allows the SOIC-8 IC package to be plugged in to a bread board (I added a photo to the top of the blog), these can also be bought from sparkfun (I think it works out cheaper to buy from sparkfun if ordering something else than using batchpcb due to the small size of the board). It’s not the easiest thing to solder but is just about manageable it with a thin solder bit (search youtube for lots of SMD soldering tutorials). This can be used on a prototype board with the Teensy or even a prototype shield on top of the Arduino.

Hope this helps, good luck

]]> By: dame http://www.rocketnumbernine.com/2009/06/27/using-the-max6675-thermocouple-to-digital-converter/comment-page-1/#comment-42 dame Thu, 23 Jul 2009 07:18:20 +0000 http://www.rocketnumbernine.com/?p=287#comment-42 Quick question. I was looking at the work you did with the max6675 chip. Would I be able to use the teensy or would I have to use an arduino? I'm trying to interface the max6675 chips with either a teensy or an arduino, and trasfer data from (2) thermocouples via USB to my computer. I spoke to a mechanical engineer and he said I would have to create a PCB, but that is just out of my league. Do you have any ideas? or maybe some PCB layouts that I might use or purchase that would work? I have some one to put it together for me, but I just wanted to see what I have to buy for him to do so. Quick question. I was looking at the work you did with the max6675 chip. Would I be able to use the teensy or would I have to use an arduino? I’m trying to interface the max6675 chips with either a teensy or an arduino, and trasfer data from (2) thermocouples via USB to my computer. I spoke to a mechanical engineer and he said I would have to create a PCB, but that is just out of my league. Do you have any ideas? or maybe some PCB layouts that I might use or purchase that would work? I have some one to put it together for me, but I just wanted to see what I have to buy for him to do so.

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