LinkMeter v2 Homebrew BBQ Controller - Part 1


 
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Originally posted by Justin:
So I just ordered the v3.2 boards and all the components and they should be here within a few days. My first question is, is it normal for the voltage from the power supply to be around 14v? I just don't want to damage the heat meter board by feeding it to much voltage.
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The HeaterMeter board can take up to 20V theoretically, so it shouldn't have a problem. The blower is only rated to 12V so I'm not sure about that. I have so many power adapters lying around I can't remember which is the Linksys one. Maybe mine puts out 14V too!
 
Originally posted by Bryan Mayland:
Ah yes. That is a really pretty piece of wiring you did there. Unfortunately it makes a fixed voltage divider (assuming your orange wire has the 10k resistor in series as well). The extra pin on the jacks is contacted when there is no probe inserted in them so what you end up with is
ATmega -> 10k resistor -> x -> 10k resistor -> Ground

We read from where the X is so when no probe is in it, you get a fixed 2.5V at the ADC. This is advantageous in that you can put a thermistor on there and have it read ambient temperature (if your coefficients are set for it). I'd not put it on the Pit probe jack though.

But yeah if you take that off (assuming you have the other 10k resistors in place) you should be good to go.
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Thanks guys, that fixed it! Although I did brand my router case with my soldering iron when I was sleepily desoldering that resistor this morning. Can you fix that too?
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Originally posted by Kyle Christensen:
Although I did brand my router case with my soldering iron when I was sleepily desoldering that resistor this morning. Can you fix that too?
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Yeah you can fix it by going like this -_- (squint really hard). Also don't take any closeup photos of it.

FOR THOSE WITH GARBLED LCD PROBLEMS
The ShiftRegLCD page has now been updated with new information! Here's what it says now about 2-wire mode

Note about the diode-resistor AND "gate"
Some tweaking might be in order to get this to work. Not all diodes can be used, and maybe you need to change the resistor value. As far as I have been able to determine, the diode needs to have a low as possible junction capacitance (and / or reverse bias capacitance as well). It seems most diodes below 5 pF should work with most LCDs and types if IC's (74HCxxx and 74LSxxx etc, CMOS etc), but I cannot guarantee this, of course.
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The 1N4001 is rated for 8pF, a Vishay or Fairchild Semiconductor 1N4148 is rated for 4pF. There is a massive discussion about possible fixes. Some are as simple as using a 4.7k resistor instead of 1k. Others replace it with a transistor, others add more decoupling caps, others build a more complex circuit.

Who still has a garbled display? Can you try replacing the 1k resistor R4 with a 4.7k?
 
I replaced the 1k with a cheap 4.7k from radio shack. It has been running with no garbled text for a little over an hour now, whereas with the 1k it would become garbled within a half hour. I'm hoping this resolves it for good. Thanks.
 
Originally posted by E. Fox:
I replaced the 1k with a cheap 4.7k from radio shack. It has been running with no garbled text for a little over an hour now, whereas with the 1k it would become garbled within a half hour. I'm hoping this resolves it for good. Thanks.
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Well that would be great news if that were the case. Looking around at other diodes, some have capacitance rated up to 20pF which I suppose is causes a problem. I don't really understand how the capacitance of the diode matters though. Maybe it makes the signal edge too slow?

Anyway, I was a little slow on getting the button board in the mail to you but you should have it tomorrow or Saturday.
 
Are the 5 pin connectors in the parts list supposed to be 6 pin? I was wiring up my lcd when I realized the 5 pin weren't going to work. Unless I missed something...

Thanks
Justin
 
Originally posted by Justin:
Are the 5 pin connectors in the parts list supposed to be 6 pin? I was wiring up my lcd when I realized the 5 pin weren't going to work.
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Ah crap, yes they are. You can use 6 1x2's though! :-D

Thanks I've updated the wiki.
 
Originally posted by Justin:
No problem. Just making sure I wasn't crazy. Thanks for responding so quickly.

Justin
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I ended up buying 2s, 5s, and 6s since having all 3 sizes means you're not using 6 pins on your serial connection, but aren't stuck using 2 pins for your LCD.
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Does anyone have an extra v3.2 board they would like to sell? I'm new to the forum, but am looking forward to building the HeaterMeter to replace my basic homegrown PID controller.

Arlen
 
I just ordered 3 from dorkbot on the 17th so I should have them in the next few days if your willing to wait a few days. Send me a message with your address if your interested.
$10 shipped sound ok?
Justin
 
Hey Justin. Thanks, $10 shipped sounds ok to me. No PM capability on this forum, so email me at arlen2 at ptd dot net and we can exchange the necessary info.

Arlen
 
Hello everyone,

This is my first time posting on a forum but I couldn't help it since I've been bit by the HeaterMeter / LinkMeter bug! Well My name is Edwin and I am a newbie, as new as it can get really. I've been eyeing this project for over a year and I've always felt intimidated by it, yet I can't shake the need to try and build this thing from my head. So I've taken plunge and I purchased all the parts listed in the latest parts list, router and I've sent off for the latest version of the PCB board (V3.2) (Laen, over at DorkbotPDX PCB Order, has been great to work with and is very responsive). I am going to try and get this built even if it kills me. I MUST! Anyhow, I've felt encouraged by the tremendous amount of knowledge on this forum and the support that many of you gentleman have displayed. I look forward to working with you all! Parts should begin to arrive tomorrow and the PCB board should arrive the week of March 12th. I hope my many questions will not bother anyone.

~Edwin
I can't wait to join the ranks of Heater/Meter-brotherhood!
 
(Laen, over at DorkbotPDX PCB Order, has been great to work with and is very responsive)
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Welcome to the fold! Yeah, Laen is great. He's actually caught an error on my board and saved me from getting back 3 boards with no drills on them. That would have not be fun. He's also really personable which is surprising considering how cheap the boards are.

Hey questions are what this is all about. I had a steep learning curve trying to figure out how to make this project, having no prior experience in hardware, embedded, or javascript programming. I'm happy to provide any expertise I have to help folks make it work. What's great is that we're starting to get a lot of people who have a HeaterMeter or variant so the more we have with the same thing, the more knowledge there is.

I'm really anxious to see how the new v3.2 design works for everyone. Plugging in the device and having the LCD spring to life is a real confidence boost.
 
Hi everyone. I am also new to this and am excited about the build. I would like to order the boards from DorkBot but when I click on the link for cam output i get a page not found error. Is this information available elsewhere? Thanks in advance!
 
I think I figured it out. I saved the text from the cam job link as a .cam, then used that with the .brd file in Eagle to output the gerber files. Hopefully that gets the right information.
 
I tried last night for 1 1/2 hours. I was able to get one into my cart on the Farnell site but couldn't get all the way through checkout. Very frustrating!
 
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