Change pit probe to use probe 1,2, or 3


 
C

CGill

New member
How do I change the 'pit probe' to be probe 1, 2, or 3?

I have a HM 4.2.4 with the thermocouple port, and I don't have a thermocouple temp probe yet, I'm using Maverick 732's in Probe 1, and 2.
 
You don't, the control probe is always the first. You can recompile the source code and switch their order but there's no UI for it because of the 3 people who have asked for the feature now 2 have only asked for it while they're waiting for their thermocouple to arrive. It represents a rather significant chunk of code to allow them to be swapped and the question of how to display it "properly" and how the remaining probes are reordered is sort of a "nobody gets it the way they expect it" problem.

It is something that will be revisited once the webui is redone where perhaps you can just drag and drop the probes around and check a box to select the control probe.
 
Yeah or you can put a piece of wire into the jack to short it out, and it will read ambient temperature if that floats your boat. But as far as using it to control the BBQ you can not.
 
I guess you could do something with a manual switch that can flip between the pit probe and another probe jack but you would have to cut the trace for that probe on the HM board and piggyback wires on the jacks to wire through the switch to the ATMEGA inputs...

Right now I have a switch that flips between the onboard TC amp and my external TC amp as the pit probe (signal injected through the lifted end of the RC filter resistor for the pit probe), and had planned to add another switch that will select between the TC (whichever is selected by the TC switch) and a standard probe jack. My plan was to use a panel mount probe jack mounted in a hole I drill in the case (instead of cutting the trace on one of the onboard HM probe jacks) If you are switching between a TC pit probe and a standard pit probe you will have to leave the pullup resistor off the HM board and use one side of a DPDT switch to switch the probe input and the other side to switch in a pullup resistor (to 3.3v) when a standard probe is selected. I have all the parts and drew up the circuit but I wanted to do the TC switch and TC to standard probe switch one step at a time, so far it's been: step 1, pause..... lol

As far as the software solution, I would (still) love to see that happen some day. Instead of adding the ability to rearrange the probes would it be easier to set it up so if you select DISABLED for the Pit Probe then the first food probe would function as the pit probe? Or maybe on the next HM you could add an optional switch that would swap the TC with the first food probe as the pit probe for a hardware solution rather than messing with the software. The HM builder could choose to add the the switch or just install jumpers to select the pit probe...
 
RalphTrimble said:
Instead of adding the ability to rearrange the probes would it be easier to set it up so if you select DISABLED for the Pit Probe then the first food probe would function as the pit probe?
Click to expand...
I really really like that idea a lot and it isn't all that complicated to do on the backend. The issue comes still with confusion on the LCD and web page I feel. It would be easiest to just leave the web items in their current place but it seems like if the pit probe is unplugged suddenly it seems like nobody is driving the car. On the LCD it would be even more confusing if it said NO PIT PROBE but was still running.

Maybe if the LCD and the control and the PID status all used the "first non-disabled probe" but the web interface always stays the same would be a good compromise. It would be nice if the webui would highlight which probe was being used to control but I think the information would get lost and it doesn't know probe types at this time, so it might be better to just leave it off for both reasons.

I think you nailed it though Ralph, I think this idea is light enough that it doesn't get in the way. Not automatic enough that it causes confusion. Achieves the goal of not locking you into the single control probe.

I have some other changes I am evaluating with tomorrow's pulled pork but after that we can try this if you think my constraints won't cripple it, Ralph.
 
That would also allow me to use my trashed TC board as thermistor pit + 2 meat unit, which would be just fine.
 
Steve_M said:
That would also allow me to use my trashed TC board as thermistor pit + 2 meat unit, which would be just fine.
Click to expand...

Trashed TC board? If you have a HMv4.2 board with SMD TC amp soldering that went bad why not just take out the last SMD resistor that connects the TC output to the ATMega (disconnecting the TC amp output) and then install a standard probe jack (and pullup resistor) to use a standard pit probe? That way you end up with 4 probes and don't need to alter the pit probe configuration...
 
Bryan, when the pit probe is disabled could you make the LCD and web interface Pit temp be the same as Food 1 temp (new pit probe), rather than saying "No Pit Probe"?
 
Yeah, maybe I'll try and move the 3rd food jack to be the pit jack. Ordering 1 more 2.5mm jack would be prohibitively expensive with shipping.
 
Steve_M said:
Yeah, maybe I'll try and move the 3rd food jack to be the pit jack. Ordering 1 more 2.5mm jack would be prohibitively expensive with shipping.
Click to expand...

In that case you might want to just lift one leg of the resistor of the RC filter on the pit probe and the probe you want to use as the pit probe, then run a jumper wire from the hole where the resistor came out on the standard probe to the lifted leg of the resistor on the Pit Probe.
 
Great idea to go to the next available probe. If mid cook your thermocouple craps out it can just read next available probe to keep the HM running, nice.
 
RalphTrimble said:
Bryan, when the pit probe is disabled could you make the LCD and web interface Pit temp be the same as Food 1 temp (new pit probe), rather than saying "No Pit Probe"?
Click to expand...
Yeah the LCD I was going to do, but the web UI will probably stay the same. It isn't as simple as just putting the number in the box, the graph would be wrong too and then you're looking at a ton of work just to make sure the value is properly copied everywhere and not just on the home page. It also means everything needs to know not just the status, but the configuration (off vs disabled is different) so it gets to be a whole big thing.
 
Well, I guess after the user has selected DISABLED for the (TC) Pit Probe they should be aware the web U/I will be reporting No Pit Probe and be running off Food Probe 1. That seems ok to me.... Like someone said earlier, if for some reason you end up with a problem with the TC or TC amp at least you can continue to cook with the HM using a standard probe....
 
Bryan Mayland said:
This feature is included in the latest AVR firmware snapshot. No LinkMeter/OpenWrt firmware changes are needed.
Click to expand...

This couldn't have come at a better time. The TC amp circuit on my working v4.2.4 board has decided to go berzerk, so now I'm left with using the 3 thermistor probes.

It really seems like I'm not meant to have a fully functioning TC heatermeter.
 
Not sure if there's any kind of update need to test... As of right now I cant control my output if the thermocouple is disabled.
 
Yeah! You don't get new software unless you update the software!

Go to AVR Firmware -> From online repository -> choose the snapshot firmware -> Flash. On the config page you should see HeaterMeter 20141222B for the version.
 
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