HeaterMeter v4.0 for RaspberyPi / Standalone


 

Dave Smith

TVWBB Super Fan
got mine built, no wireless....I hope I'm not going to have that same problem I had connecting the linkmeter! also, forgot to install the wireless usb thingy before I booted it up, that might be my problem.
 
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Alan Erickson

TVWBB Fan
I'm having problems with my temperature probes, the problem being that it doesn't recognize anything I insert. No matter what I get "no pit probe" and nothing on any of the other channels. I have four probes and have the thing "loaded up" with all four probes and nothing comes through on any channel. Not sure if it's a software or hardware problem. Any suggestions for trouble shooting? I've seen this problem once or twice before, but it went away after "rewriting" the SD card.
 

Bryan Mayland

TVWBB Hall of Fame
I'd say troubleshoot the hardware first. Get a multimeter on the probe connector J2. Measure the voltage with nothing inserted into the pit jack between pin 1 (labeled GND) and pin 2. You should get 3.3V. Now insert the pit probe and the voltage should drop. You should get this same voltage at pin 28 of the ATmega chip. To determine the voltage you should see, remove the pit probe and measure the resistance (R). The voltage from the preceding step should be 3.3 * R / (R + 10000).

If that's working then check your probe configuration in the web interface. If that looks right, maybe use the menu on the HeaterMeter itself to "Reset configuration", power everything down, and back up again, then try configuring the probes again from the web interface.
 
I just got the jacks for my probes from Digikey, the IGrill probes plug right in, I'm seeing some info that says they may interchange with maverick probes other than the amount of projection of the tip of the plug ?? maverick probes are still inbound. rPi showed up today, ordered Saturday from Amazon. It is a rev 2.0 512...it will still work the same with the heatermeter, looks like nothing changed if I understand properly ?

Bill
 
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Bryan Mayland

TVWBB Hall of Fame
If they're just resistive probes, they should work. However, they may not have the same response curves as the pre-defined probes so you may need to calculate your own coefficients.
 
If they're just resistive probes, they should work. However, they may not have the same response curves as the pre-defined probes so you may need to calculate your own coefficients.

It seems nobody really knows if they are the same or not, I guess we will learn something eh ??.....it would not really make sense for IGrill to dream up a whole new type of probe, but then who knows :). I have some Maverick ones on the way too.
 

Alan Erickson

TVWBB Fan
Bryan, I did everything you mentioned and everything looks good.

A couple of weird things though. I'm using Maverick ET-732 probes. If I touch the probe wire jacket to the HDMI port casing the probe gives me a correct reading. If I pull it away it goes back to no pit probe. Then, when it's reading no pit probe if I take a lighter and heat the probe up when it gets to around 200 F I get a reading again. Then when the probe cools to around 120 F it drops back to no pit probe again.

How does the system tell if the pit probe is connected? The voltage difference comparing connected and disconnected seems pretty small.
 
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D Peart

TVWBB Pro
Alan,
You used to be able to set the setpoint to R and see what the resistance value of the probe is, but I just tried it for the pit probe and it doesn't seem to work. I get some non-nonsensical value. It does work for the food probes though, at least it appears to give me a better number.

You could try it and see what the food probe reads. To get the ET-732 probes I have to make sure there are not sharp bends or kinks in the wires.

dave

Bryan, I did everything you mentioned and everything looks good.

A couple of weird things though. I'm using Maverick ET-732 probes. If I touch the probe wire jacket to the HDMI port casing the probe gives me a correct reading. If I pull it away it goes back to no pit probe. Then, when it's reading no pit probe if I take a lighter and heat the probe up when it gets to around 200 F I get a reading again. Then when the probe cools to around 120 F it drops back to no pit probe again.

How do you tell if the pit probe is connected?
 

John Bostwick

TVWBB Wizard
Bryan, I did everything you mentioned and everything looks good.

A couple of weird things though. I'm using Maverick ET-732 probes. If I touch the probe wire jacket to the HDMI port casing the probe gives me a correct reading. If I pull it away it goes back to no pit probe. Then, when it's reading no pit probe if I take a lighter and heat the probe up when it gets to around 200 F I get a reading again. Then when the probe cools to around 120 F it drops back to no pit probe again.

How do you tell if the pit probe is connected?

Edit: The readings I that I took were: Voltage without probe connected = 3.30 V, Voltage with probe connnected = 3.27 V, Resistance of probe = 1123k ohms

it sounds to me you have a bad ground, Try to resolder using a solder flux, to get a good connection. The jacket of the probes are its ground, so when you are touching the probe to the HDMI port, which is grounded, it makes a connection and so you get a tempeture reading.
 

Alan Erickson

TVWBB Fan
I should have posted my readings. They were: Voltage without probe connected = 3.30 V, Voltage with probe connected = 3.27 V, Resistance of probe = 1123k ohms

I'm surprised the resistance reading is so high.

Edit: If the probe is a thermocouple (voltage) versus an RTD (resistance change with temperature) will the system still work properly?
 
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D Peart

TVWBB Pro
1.1Mohms is about right for 78F.

I agree with John, check your ground connection. Can you get temps to work correctly on any of your food ports?

dave

I should have posted my readings. They were: Voltage without probe connected = 3.30 V, Voltage with probe connected = 3.27 V, Resistance of probe = 1123k ohms

I'm surprised the resistance reading is so high.

Edit: If the probe is a thermocouple (voltage) versus an RTD (resistance change with temperature) will the system still work properly?
 

Alan Erickson

TVWBB Fan
I agree, it seems like a grounding problem. I'll double check everything but my solder joints look pretty good.

What's weird is if I take a jumper and go from the HDMI on the Rpi to the ground on J2 on the HeaterMeter board it doesn't fix the problem. Also, there was a point where I could just squeeze the HDMI port on the Rpi without touching the HeaterMeter board and that would fix the problem also.

I checked the resistance from the braided sheething to the two points on the jack and everything is open (no resistance). Wasn't what I was expecting so I'm not sure what the sheething is grounding to when I touch it to the HDMI port casing.

I do/did have two checksum errors also. Not sure what that means.
 

Bryan Mayland

TVWBB Hall of Fame
1.1Mohms is about right for 78F.
Golly, that is so crazy high. HeaterMeter will display "No Probe" for readings which are really close to reference voltage (1-2 ADC 'ticks'). The voltage divider you've got going there is:
1.1M / (1.1M + 10k) = 0.991 = 3.2703V

While that should give a reading (1014 out of 1023) that's still pretty close to the top end. Looking at the curve for that probe, they seem particularly unsuited for reading temperatures below 100F. You'd be able to get much more accurate readings by choosing different biasing resistors for the probes.

That said, you should still be getting readings out of HeaterMeter. Without the system powered on, try checking the resistance between the metal braid on the probe wire the ground on the probe pin header (with the probe plugged in). It should read 1 ohm or less. Also try taking the same reading with the probe touching the HDMI shield which you say gives you a reading. They should be the same value.

EDIT: Oh hey you've already tested that. They shouldn't read open, that's for sure. Check to make sure the probe pin is seating properly in the jack. You should get near-0 ohm resistance between pin 1 of the probe jack header and the braid of the probe cable.
 
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D Peart

TVWBB Pro
Oh yeah, don't push then all the way into the jack. They won't work. You have to pull them back out of the jack about 2mm, you'll feel it click.

I use a 20k ohm resistor for my ET-732 probes as it makes the <100F work better.

dave

Golly, that is so crazy high. HeaterMeter will display "No Probe" for readings which are really close to reference voltage (1-2 ADC 'ticks'). The voltage divider you've got going there is:
1.1M / (1.1M + 10k) = 0.991 = 3.2703V

While that should give a reading (1014 out of 1023) that's still pretty close to the top end. Looking at the curve for that probe, they seem particularly unsuited for reading temperatures below 100F. You'd be able to get much more accurate readings by choosing different biasing resistors for the probes.

That said, you should still be getting readings out of HeaterMeter. Without the system powered on, try checking the resistance between the metal braid on the probe wire the ground on the probe pin header (with the probe plugged in). It should read 1 ohm or less. Also try taking the same reading with the probe touching the HDMI shield which you say gives you a reading. They should be the same value.

EDIT: Oh hey you've already tested that. They shouldn't read open, that's for sure. Check to make sure the probe pin is seating properly in the jack. You should get near-0 ohm resistance between pin 1 of the probe jack header and the braid of the probe cable.
 
Cool. They should have used a screen shot that had a more stable graph, then the sawtooth wave screen shot

I sent Liz an e-mail with a link to the Linkmeter forum a couple weeks ago because I saw UberFridge on their blog and I thought everyone should know about Bryan's awesome PID project! I have learned so much from Bryan!

Oh and by the way...this new forum software is not working for me. I have subscribed to this and a couple other threads multiple times. I get e-mails for the first few days but then they stop. It has made it hard to keep up with the threads. Anyone else have this issue?
 

John Bostwick

TVWBB Wizard
I sent Liz an e-mail with a link to the Linkmeter forum a couple weeks ago because I saw UberFridge on their blog and I thought everyone should know about Bryan's awesome PID project! I have learned so much from Bryan!

Oh and by the way...this new forum software is not working for me. I have subscribed to this and a couple other threads multiple times. I get e-mails for the first few days but then they stop. It has made it hard to keep up with the threads. Anyone else have this issue?

Bryan has taught me alot sinse I made the first heatermeter last year using wrapping wire, now im on my 5th HT. I never thought I would be going to a BBQ forum and learning electronics and programming.

Not sure about the email notifications. I know some forums will send you an email of a new post and if you don't go to the forums to see that post, then they will not send you any more emails to let you know there had been new post. Only after going to the subscribed post then the emails will again let you know if there had been any new postings. Also, if there are multiple posting then they will only send one email and wont send multiple emails unless there is certain amount of time between new postings.
 

 

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