HeaterMeter v4.0 for RaspberyPi / Standalone


 
Any 12VDC with > 1A current and 2.1mmx5.5mm will work. Do not buy the 2.5mmx5.5mm power supply. I wont work reliably with the DC power jack (too big).

dave
 
Kyle, RJ, and D Peart,

Thanks for the info for answering my questions. I think I just happen to have an old Linksys RT54G router unused upstairs in a box, so it looks like I'll use that for a wall wart. It's good to hear I can use the 732 probes, I'll probably make some little standoffs with plastic tubing for the probes like others here have suggested, preventing the probes from getting plugged in to far. Also thanks for the blower hookup info, much appreciated!

Now as soon as Mr. Miller gets back to me about the case I ordered, I should be in business in about a week, hopefully.

Thanks again guys, you all are a great bunch of friendly folks!

All the best!

Jeff
 
I have been watching this thread for a long time. Even though I have little elecronics experience I finally decided to give it try. Finished my Heatmeter last weekend. The only issue I have is that Probe 1 temp is always floating and generally 30 to 70 degrees high. If I disable it and do a boiling water test I get 212 degrees (+ or - 5) on Pit and Probes 2 and 3. I have swapped probes and verified all the setting match my ET-732 probes. Reflowed to solder on the probe 1 connections. I dont see any other cold solder joints. Is there a specific resistor to drive probe 1. I saw on another post about checking voltages and resistance with and without probes. I will try that tonight. Any other idea's on what could be the cause??

Thanks
Bruce
 
Bruce,

Did you check for continuity across R17?

Meter across these two points for 10K.

ginW78J.jpg


Matt
 
Looks like its there 9.75 on a 20k scale.

None of the probe jacks are shorted to ground. Is 9.75 acceptable? Seems like probes 2 and 3 are closer to 10k at 9.89 and 9.94.

M Miller said:
Bruce,

Did you check for continuity across R17?

Meter across these two points for 10K.

ginW78J.jpg


Matt
Click to expand...
 
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Those are supposed to be 10K 1% resistors...so anything above 9.9K should be OK Do you happen to have a spare 10K handy? If not maybe radioshack for a quick fix...

I wonder if you could take the average resistance and redefine the resistor values in software? At least then the total error would be minimized, with some probes high and others low.

Gotta run!
 
you could go change your config page for probe one to be 9.75 instead of 10.

though measuring in-circuit can lead to misleading results.
dave
 
The way I designed the circuit, if you don't have a probe attached (and no ambient thermistor), the resistors are left floating and are perfect for being measured with a multimeter and entering the number directly into the config page. Pretty sweet, huh?
 
Still not really sure where my problem might be. I checked voltages at the probe connector J2. Probes 2 and 3 are at 3.27 volts. Probe 1 is at 3.23v and the pit probe is at 3.18v. Everything drops a bit when a probe is inserted. I wonder if my power supply is a little weak. By adjusting the config page resistance and offset I can get the temps all looking correct but I have -25 in one of the offsets. Is a big offset number like that acceptable.
Thanks Bruce
 
Yeah the offsets should really be 0, because the response of thermistors is non-linear. That is, if you adjust the offset for one point, all your other points will be off because you can't simply shift the range up and down, you have to adjust the curves. This is what the ABC coefficients are for.

The voltages you read at the probe resistors should exactly match the power line voltage. This isn't a comprehensive diagram of all the pin voltages but it is a good start:
hmpi-power.png

Note that all the red 3V3 dots should read identical values (with no probes plugged in). If you're seeing differences at one point versus another, something is definitely not right. You might try populating the 3.3V regulator on the HeaterMeter board and running it standalone to test voltages without the Pi. Any MCP-170x (1700, 1702, etc) TO-92 package 3.3V regulator will do if you didn't but the part from the wiki parts list.
 
Thanks Bryan I will take a look. At this moment things have gone down hill. I thought I had a cold solder joint on the Pi Connector. After that it won't comminicate with the PI. Solder under the connector may have formed a short. I hate the thought of trying to remove that connector. Just prior to failing I had 3.3v accross all of the 10K resistors so i was making progress. To be sure I loaded up the PI standalone with Wheezy.IMG? and I think it is still working correctly. I did order the full parts list so i have the 3.3V regulator.


Thanks
Bruce
 
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First I want to thank Bryan for the hard work on this. I have ordered all the parts and most have been delivered. I'm looking forward to starting my build this weekend.
Thanks,
Rob
 
Thank you Bryan and everyone else for your hard work that have contributed to this wonderful stoker. I have been following this thread since it started. But I first got interested with the LinkMeter. Just finished populating the hm board and testing it and i have to say it is a wonderful tool to have. I only have one problem, I must have received a bad tactical switch because after start up, the meter will start switching between lid open and fan speed % on the screen. I unsoldered the switch and all works great. So already have a new switch on its way along with another SD card. Should be here tomorrow!! Again thanks for showing me the light lol!!
 
Bryan Mayland said:
Yeah the offsets should really be 0, because the response of thermistors is non-linear. That is, if you adjust the offset for one point, all your other points will be off because you can't simply shift the range up and down, you have to adjust the curves. This is what the ABC coefficients are for.

The voltages you read at the probe resistors should exactly match the power line voltage. This isn't a comprehensive diagram of all the pin voltages but it is a good start:
hmpi-power.png

Note that all the red 3V3 dots should read identical values (with no probes plugged in). If you're seeing differences at one point versus another, something is definitely not right. You might try populating the 3.3V regulator on the HeaterMeter board and running it standalone to test voltages without the Pi. Any MCP-170x (1700, 1702, etc) TO-92 package 3.3V regulator will do if you didn't but the part from the wiki parts list.
Click to expand...

I was able to look at the voltages. I am missing 3.3v on the pins with blue arrows. Anyone have suggestion for the next steps. I could have a solder short under the PI connector but before I go down the path of trying to unsolder the connector i wanted some input. Thanks for the help.
Bruce


image_zpsc299e290.jpg
 
Bruce,
Those two pins are connected together, so the good thing is that they are reading the same :)

It is the rPi TX net so I'm not sure why there were marked as reading 3.3V unless there is some way to hold the signal high. I would expect that it would be fluctuating if the rPi is turned on.

Bryan will have to give you some more ideas.

dave
 
Dave,
i did suspect that was TX on the drawing but i was a little confused as to how the pinouts on the chip actually line up. I did put the 3.3v regulator in so am running the heatermeter standalone. Still suspect something under the pi connector. Is there any continuity checking I can do to identify a short?

Thanks
Bruce
 
B Severson said:
Dave,
i did suspect that was TX on the drawing but i was a little confused as to how the pinouts on the chip actually line up. I did put the 3.3v regulator in so am running the heatermeter standalone. Still suspect something under the pi connector. Is there any continuity checking I can do to identify a short?

Thanks
Bruce
Click to expand...

If it runs standalone fine, but not with the rPi I would look at the pin you showed as not being 3.3V. The two with the blue arrows should be connected together and to nothing else. So check the pins adjacent to them.

Additionally you can check the pins to the left of the two blue arrows, at both places and they should be connected to each other, those are the matching tx/rx signals.

They also connect to the FTDI heard above the arudino between the VCC and Reset (RST) pins.

dave
 
The TX pin seems fine not shorted to ground or any other place on the PI connector. Continuity with the Tx pin on the ATMega TX pin and not shorted any place on that chip. Also VCC has 3.3v.
 
This may be a shot in the dark, but you did install the rPi header in the right position, not shifted to the right by one or more rows of pins? There should be 3 pairs of pins between where the header ends and the probes.

dave

B Severson said:
The TX pin seems fine not shorted to ground or any other place on the PI connector. Continuity with the Tx pin on the ATMega TX pin and not shorted any place on that chip. Also VCC has 3.3v.
Click to expand...
 
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