HeaterMeter v4.0 for RaspberyPi / Standalone


 
Ehhhh it might could work with 0.5A 12V, at least to boot, no WiFi. When the fan turns on it will definitely be too much draw. I'm not sure if that explains everything you're seeing though.
 
Going to have to mess around. When I push the button to the left the middle LCD light comes on. I can make the LCD bright and lower. Everything looks like it is in the right place and the solder joints look good. The new power supply comes Tuesday. I didn't attach the blower fan yet.
 
Ok figured out some stuff. I assume it is working. None of the three LED lights are lite up, but I adjusted the contrast on the display and it says no pit probe now. I haven't plugged any in yet. I should see one of the three lights lit at this point?

If I push the button to the left the middle of the three will light up.

I'm able to go through the menus and such on the display and pick the temps, etc
 
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Just got back from the NJ state BBQ championship where my heatermeters put in some serious work. This thing was 3 days long and I could not have made it through without the alarm features of the HM waking me up when I needed to do something. Out of 65 teams we took 5th in chicken, 5th in pork, 8th in brisket, and 42 in ribs (don't know what happened there), for an overall of 9th place. I was pleased with the result being that it was our first competition. The BBQ guru team was across from us and I got a lot of people asking me about the heatermeter so I pointed them in the direction of this site. Thank you again Bryan for creating this project.
 
Tom Kole said:
Just got back from the NJ state BBQ championship where my heatermeters put in some serious work. This thing was 3 days long and I could not have made it through without the alarm features of the HM waking me up when I needed to do something. Out of 65 teams we took 5th in chicken, 5th in pork, 8th in brisket, and 42 in ribs (don't know what happened there), for an overall of 9th place. I was pleased with the result being that it was our first competition. The BBQ guru team was across from us and I got a lot of people asking me about the heatermeter so I pointed them in the direction of this site. Thank you again Bryan for creating this project.
Click to expand...

Congrats on the great results Tom!!! If available, post some pics. Thanks.
 
Tom Kole said:
Just got back from the NJ state BBQ championship where my heatermeters put in some serious work. ... for an overall of 9th place...
Click to expand...
That's so awesome! Congratulations, that's a really great showing especially considering it was your first competition. Even better, I'm glad everything worked and didn't let you sleep through anything important. 3 days though, I bet you're exhausted.
 
The 4 x 390 ohm resistors at mouser were back ordered for several weeks so I picked up some 330 ohm resistors from a surplus store nearby as they were also out of 390 ohm resistors.

Think I'll be in danger of frying anything with 18% less resistance on those 4?
 
3 of them just drive LEDs at well below their rated current so they're ok. The other is for one of the button directions. That code is pretty wide in its tolerance, but I can't guarantee that it will work. It definitely won't fry anything though.

For anyone else that runs into the same situation, mouser stocks all manner of samey resistors so just ask and we can locate a substitute.
 
I'm not sure if I should post a troubleshooting question in this thread or in a new thread, so I'll start here. I put together my HM, loaded the image, and it booted on the first shot (YAY!). Everything works great, EXCEPT I think there's a short somewhere that involves the Pit probe. Probes 2, 3, and the "Ambient" thermistor all work fine. When I plug the probe into the Pit jack, the display shuts off, and the voltages across all the 3.3V contacts drops to around 2.4V. I'm not sure where I should start looking for problems. Without anything plugged into the Pit jack, all of the 3.3V and 5V contacts read correctly. It just goes wonky when I plug the Pit probe in.

Thanks in advance and let me know what other information I can provide to assist in troubleshooting. And obviously thanks to Bryan for putting this amazing project together and helping everyone out.

-Adam
 
That's a strange one. The really strange thing is that the input to the jack runs through a 10k resistor so you can't short it from that direction. When you put the probe in, the probe is like a 220k ohm resistor so it can't short through the probe either. I'm staring at the schematic and I can't seem to see how anything even runs by there that could cause what you're seeing.

The pin on the back of the probe jack isn't bridging to pin one of the ATmega is it?


Check the resistance without it powered up and make sure they're not connected (well technically they're connected but shouldn't be low resistance). If they are I could see the pit probe pulling down the reset line and holding it in reset maybe.
 
Measuring between those two pins, I get 19.8kOhm with the HM powered down. I can't see any obvious physical bridging between the ATmega and the back of the Pit jack.
 
Another data point: when I measure the resistance between J2 and J3 using the 20k Ohm scale, it reads the pit temp as 214*F. When I use the 200k Ohm scale, it reads the pit temp as 102*F. When I do the same readings using the pins on the pit probe jack (back and front), I get a reading of 300*F for both the 20k and 200k Ohm scales.

Not sure if any of that information is helpful...

Thanks!

-Adam
 
OK, so my initial proclamation that everything works except for the pit probe was a bit premature. When I set the fan mode to manual and enter use the web interface to activate it (by entering a value < 0 in the set point field), it exhibits the same behavior as when I insert a probe into the pit jack: the display turns off and it kills the web interface until I power cycle the device. So perhaps it has nothing at all to do with the Pit probe and everything with the fan circuit. Anything that would cause the fan to power on (like plugging in the pit probe at room temperature or setting the fan to run manually at 10%) causes my problem.
 
Ah! Yes that does point to something in the fan circuit! Check the polarity of your diode that is between the shift register and the 5V regulator sub-board (IC1). The band on the diode should be pointing towards the pi (or away from you if the device is upright). If that's reversed, when the fan turns on it shorts 12V to ground which would do something like you're seeing.
https://picasaweb.google.com/lh/photo/Vejhy0c2FNbQ-8BVBCFh9dMTjNZETYmyPJy0liipFm0?feat=directlink

Also make sure your MOSFET is installed not flip turned upside down I guess. Although that would be fairly obvious.
 
Bryan,

Thanks for your help. I'm fairly confident that the problem is in the fan circuit, as setting the fan control to manual and plugging a probe into the Pit jack does not exhibit the behavior, nor does plugging a probe into the Pit jack with a set point < room temperature. However, both the above-mentioned diode and the mosfet are installed correctly. Are there any other relatively easy troubleshooting approaches you can suggest?

-Adam
 
Alright, maybe there's a short in the RCA jack area? The 12V and GND are pretty close there thanks to the external blower pinheader. Check on the pinheader that there's no continuity between the pin on the J4 labeled side and the 12V labeled side. Basically that everything connected with lines here doesn't have continuity with another thing with a line.
 
OK. Based on your description, I tested for continuity at the two pins indicated in the below picture with a red and a yellow arrow.
HMtshoot.png

With my meter's red lead on the pin with the red arrow and the black lead on the pin with the yellow arrow, I get continuity. I do not get continuity with the meter leads reversed (red on yellow arrow and black on red arrow).

FWIW, here's a pic of the front of my board (yes I know my soldering is abominable; this was my first attempt soldering pcb):
IMG_0259.JPG
 
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That does make sense as they are connected through that diode you've already checked and that verifies that the diode is conducting in the proper direction. The mosfet must be working properly too or else it would always be not working, not just when it is on. I'm really not sure what else to check. Maybe feel the chips when the power gets all wonky and see if you find one that's getting warm? They should all be close to room temperature, especially when no blower is physically connected.
 
When I get the problem, the 5v voltage regulator and the fan mosfet both get well above room temperature. As in, I can't hold my finger against them for more than ~.5-1 sec before it starts to hurt. My IR thermometer reads between 125-140F, with a room temp of around 77.
 
I'm just grasping at straws at this point but it definitely sounds like something is shorting when the fan is on. Is the capacitor to the right (in the image you posted) of the RCA jack, closest to where it says BLW, inserted correctly? Normally if inserted backwards they just become "not capacitors", not shorts though. Might as well check that with the meter too, see if it has low resistance between the contacts.
 
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