So apparently I have to hook up the CS, SCK, MISO, 3v3, GND, etc for a thermocouple, and I understand that I can use ‘chip_select_pin’ to change the CS pin, but what pin(s) can I use for that?
All the pins (SCK, MISO, 3v3, GND) are shared by multiple thermocouples except the CS, correct?
It would be really nice if there was documentation actually showing the wiring for [multiple] thermocouple(s) and sample configuration. 
Imported from wikidot
I believe the person that added thermocouple code added the possibility to use multiple ones, but did not test it ( it’s a pretty rare setup )
A few weeks back somebody tested it and found a bug when using multiple ones. A fix is planned but I don’t think it’s been done yet.
All the pins (SCK, MISO, 3v3, GND) are shared by multiple thermocouples except the CS, correct?
Yes you are correct.
Also, please note, if you are using a RRD GLCD, it does not implement SPI properly, and will not allow you to share the SPI bus with other devices ( this is a bug in their hardware, there is nothing we can do on Smoothie’s side to fix it ).
Well that sucks. I sure have wasted a lot of time and some money on the LCD that I won’t be able to use.
If it is RRD’s fault, why does the RAMPS board work with thermocouples and the RRD GLCD?
Before I purchased the board you told me it would work with 3 thermocouples in this thread:
smoothie ware dot org slash forum slash t-1354109 slash 3-thermocouples
If I can’t use multiple thermocouples reliably this board has done nothing but waste my time and money. And I will have to return the board - $150+ isn’t exactly cheap.
When you market the fact that your board supports up to 4 hotends, why is it so unusual to have two thermocouples? Do people really run one hot end on a thermocouple and the others on thermistors? That seems quite odd to me.
Also - why on earth didn’t you mention this in my other thread “Settings for 3 thermocouples”. You could have saved me a lot of time by saying its probably not going to work, or you don’t know that it works - or something!
Different microcontrollers have different sets of peripherals. I would expect the RAMPS has an additional SPI port that is used for this, so the RRD GLCD is alone on it’s port and therefore not disturbed by the thermocouples.
The RRD GLCD incompatibility is documented in the thermocouple section, but not in the RRD GLCD section, I’ll add it there now.
Before I purchased the board you told me it would work with 3 thermocouples in this thread:
The discovery of that problem is very recent, the first person to try it was in september I think ( it could have been a bit before but I was away end of august/beginning of september ).
Jim Morris has said he would fix the bug, but is waiting on receiving his thermocouple boards to be able to test/fix it.
When you market the fact that your board supports up to 4 hotends, why is it so unusual to have two thermocouples? Do people really run one hot end on a thermocouple and the others on thermistors? That seems quite odd to me.
You are the second person I know planning a multi-thermocouple setup, the other one was very recent and discovered the multi-thermocouple problem.
Smoothieboard has 4 thermistor inputs, so you can run up to 4 hotends ( or 3 hotends and a bed ) on thermistors. You can also run 4 hotends and one SPI thermocouple bed ( I know of several setups like this, it sounds like the simplest way to a 4 hotend setup ).
Additionally, there is an extra ADC, and with a resistor and capacitor, you can turn it into an extra thermistor input, I *think* somebody is using this to run 4 hotends + 1 bed all on thermistors. If you have 4 hotends and a bed, you could theoretically do this.
Also - why on earth didn’t you mention this in my other thread “Settings for 3 thermocouples”. You could have saved me a lot of time by saying its probably not going to work, or you don’t know that it works - or something!
At that moment I was aware of the multi-thermocouple bug, but it was very recent, and I missed the connection. Sorry about that.
This bug occurred because that functionality had never been tested. It will get fixed.
Well I asked if multiple thermocouples worked on September 9th, and you told me they would work. Why didn’t you say what you are telling me now - that its untested and/or buggy???
Also, it is clear you knew about this after I started my thread on three thermocouples and again you said nothing about this. Adding to that you knew I had a thread on the GLCD and one on thermocouples and yet you knew they aren’t compatible. You could have saved me a lot of frustration.
I am very upset now, I have spent a full on this board now only to have to return it? And worse than that I am back to where I started.
As I said, while I did see the bug report on multiple thermocouples sometimes in september, I did not notice the connection to your post. I apologize again. I have been moving houses and have been answering forum posts with more hurry than usual.
You are trying to do something that as far as I know, has only been attempted once before, and only recently. Many-extruders machines are not common, and you *should* expect some amount of effort/frustration doing something innovative like that, as both the community and the firmwares are obviously more reliable when doing older/simpler things than when doing very new/innovative things.
The multi-thermocouple bug should be fixed relatively soon. Once that is done, you should be able to run your machine as you wish ( except for the RRD GLCD due to it’s limitations ).
Can you tell me more about your machine ? Exactly how many hotends and other peripherals does it have ? Also some more general info.
I don’t see how you could have missed that - the name of the thread is “3 thermocouples”!!!
:’(
I would have expected some effort, but your documentation treats thermocouples as a configurable heater module (and it states up to four modules are configurable), so they should work. Also, I directly asked before I purchased, you should have told me you didn’t know if it works and might need some tinkering. So I thought I was buying a product that supports my needs (thats why I asked before purchasing).
It was going to be used for a huge optical glass printer: glassprinted dot com
I had intended the smoothie to control 3 SSRs each with a thermocouple. One is for a 220V 4KW oven, another for a 220V 2KW furnace and another 220V 300W nozzle heater.
I am basically ready to turn the heat on now only to find out that I can’t. I can’t wait for a solution to come up - I have a lot invested in this and will have to use a solution that works today - not someday in the future. Super disappointing.
I would prefer to keep the board then return it. Can you give me a realistic estimate when multiple thermocouples will be supported?
OK - well I tried - guess I will return it. Are you going to update your documentation then to state that only 1 thermocouple is supported as a heater module? Might save other folks a *lot* of trouble.
Arthur - do you know if this has been resolved?
There is a pull request for this, which is waiting for somebody who actually owns several thermocouple boards to test it, before it can be merged.
If you are interested in testing it don’t hesitate to say.