LinkMeter v2 Homebrew BBQ Controller - Part 2


 

Neil Mager

TVWBB Member
I'm glad they helped. The board is very tight, so I found a conical tip worked much better then a chisel tip on the iron.


Originally posted by Kyle Stierwalt:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Neil Mager:
I used heatermeter.cpp.hex, renamed it to hm.hex and ran avrupdate and it worked - I connected my pit probe up and got a temperature reading!

I put together a picasa album building up the board. It roughly coincides with Bryans steps here: http://tiny.cc/jmqrfw

Picasa Album - http://tiny.cc/bnqrfw

Bryan - if any of these will help with the wiki, feel free to use them.

Now to solder up the probe jacks and mount the lcd display.

Thanks Neil. I'm just getting ready to begin the project; I think I have all the parts now and ready to start soldering once my Hakko 888 arrives. The photos are exactly what I needed...very helpful. Thanks. </div></BLOCKQUOTE>
 

J. Winn

TVWBB Fan
Below is a list of blowers I have come up that have around the CFM that i think would be needed while still maintaining a lower current draw.

This one seems the most promising. Its 20CFM but only has a current rating of .2A, the one in the parts list draws .18A.
20CFM fan

This one has a 5CFM increase but draws .470A so I'm not sure the trade off is worth it.
25CFM fan

Current draw is .370A
23.2CFM fan

Current draw is .4A, which seems better than the 25CFM above due to the fact that I'm only losing .3CFM but has a lower current draw.
24.7CFM fan

This one has a better volatge range and draws .320A. I may be leaning towards this one.
19.1CFM Fan

What do you guys think? If I'm missing anything let me know. Not sure if the operating voltage range matters or not for the fan speed control aspect. Thanks again!
 

Bryan Mayland

TVWBB Hall of Fame
Originally posted by RJ Riememsnider:
This is all i got:
lr-x------ 1 root root 64 Sep 8 15:56 3 -> /dev/ttyS0
lr-x------ 1 root root 64 Sep 8 15:56 3 -> /dev/ttyS0
root@OpenWrt:/proc#
Hrm that may be the `cat` if you were running that at the time, but if not then that's definitely got the serial port open. Try this

cd /proc
find -type l | xargs ls -l 2> /dev/null | grep /dev/ttyS0

It should find some results except this time it will be prefixed by another number like:
lrwx------ 1 root root 64 Jun 13 00:54 ./910/fd/5 -> /dev/ttyS0

Then do a `ps` and see what that number refers to. 910 in my case is the lucid process.
 
I killed off the cat processes and when I did find -type l | xargs ls -l 2> /dev/null | grep /dev/ttyS0

It came back with nothing.

Guess the ports really are bad.
 

Shane Woessner

TVWBB Member
Originally posted by J. Winn:
Below is a list of blowers I have come up that have around the CFM that i think would be needed while still maintaining a lower current draw.

This one seems the most promising. Its 20CFM but only has a current rating of .2A, the one in the parts list draws .18A.
20CFM fan

This one has a 5CFM increase but draws .470A so I'm not sure the trade off is worth it.
25CFM fan

Current draw is .370A
23.2CFM fan

Current draw is .4A, which seems better than the 25CFM above due to the fact that I'm only losing .3CFM but has a lower current draw.
24.7CFM fan

This one has a better volatge range and draws .320A. I may be leaning towards this one.
19.1CFM Fan

What do you guys think? If I'm missing anything let me know. Not sure if the operating voltage range matters or not for the fan speed control aspect. Thanks again!

I use this fan http://www.surpluscenter.com/i...tem=16-1358&catname=
with this power supply http://www.ebay.com/itm/280870...id=p3984.m1497.l2649

I've used the linkmeter 3 times now on my large reverse flow smoker (3'x5' cook chamber with a 2'x2' fire box) with no problems. Hope this helps.
 

J. Winn

TVWBB Fan
I looked at the routers:
WRT54G V2
<UL TYPE=SQUARE> <LI> Broadcom BCM4712 @ 200 MHz
<LI> 16 MB RAM
<LI> 4 MB Flash
<LI> Some of these have 32 MB of RAM but are locked to 16 MB in the firmware [/list]

WRT54GS V2.1
<UL TYPE=SQUARE> <LI>Broadcom BCM4712 @ 216 MHz
<LI>32 MB RAM
<LI>8 MB Flash [/list]

WRT54GL V1.1
<UL TYPE=SQUARE> <LI>Broadcom BCM5352 @ 200 MHz
<LI>16 MB RAM
<LI>4 MB Flash [/list]

GS seems to have the best specs; most memory slightly faster processor. I don't know if that really matters or if its best to use the GL since the Heatermeter board will fit better.

Also, about flashing the bootloader. I have an old serial port icsp programmer that I was going to use. The only problem is the programmer has a 6x1 connector and it looks like the header at J6 is 2x3. Any suggestions?
 

Riku Naskali

TVWBB Member
Got my Linkmeter finally working, it's awesome!

How hard would it be to add a feature to automatically shut down the fan when meat is almost at target temp? Say, something like 35 degrees F before the target temp. One could pretty easily predict the temp rise after a couple of cooks.

Also, is there a downsize to changing the mosfet to more capable and still running the original fan? I'm thinking of making the Linkmeter more universal with bigger fans and pits.

I have the following mosfets right now: IRLIZ24NPBF-ND and IRLB8743PBF-ND, both should be pretty capable according to my information
icon_smile.gif
 
Hmmm, I guess since the GL 2.1 wasn't listed in the openwrt table I assumed it wasn't supported due to lower capacity just like the wrt54G 5+ routers. The GS 2.1 clearly has enough storage though. Still for ease of mounting, I would use the GL. For what we're using them for, you won't notice a difference.
 

Bryan Mayland

TVWBB Hall of Fame
Originally posted by Riku Naskali:
How hard would it be to add a feature to automatically shut down the fan when meat is almost at target temp?

Also, is there a downsize to changing the mosfet to more capable and still running the original fan? I'm thinking of making the Linkmeter more universal with bigger fans and pits.
The automatic shutdown is part of the Alarm system that I'm sort of working on. One of the actions you'll be able to configure is a setpoint change.

The MOSFET in the project is good for 60A/60W with an Rds(on) of 0.009 ohms. How much more capable a part are you looking for? I'd be more concerned with the electrical noise of a giant fan switching on and off hundreds of times a second wreaking havoc on the sensitive electronics.
 

J. Winn

TVWBB Fan
Also, about flashing the bootloader. I have an old serial port icsp programmer that I was going to use. The only problem is the programmer has a 6x1 connector and it looks like the header at J6 is 2x3. Any suggestions?

I am including a picture with the box so everyone can see what i'm talking about. Maybe it won't work; it says ICSP though.
icon_confused.gif

Programmer
 

Bryan Mayland

TVWBB Hall of Fame
Originally posted by J. Winn:
I am including a picture with the box so everyone can see what i'm talking about. Maybe it won't work; it says ICSP though.
icon_confused.gif

Programmer
Iiiiii don't think so, looking at the datasheet. It looks like that is for the PIC variety of ICSP. I don't know enough about electronics to say what the schematic does. I'm sure they're somewhat similar in function, but this looks like one-way communication with a 13V MCLR signal at the start. The ATmega programming is only 1.8V-5.5V generally except in the case of high-voltage programming with 12V on the reset line.

I don't think it will work, it might, but it would definitely require some technical jiggering.
 

J. Winn

TVWBB Fan
Originally posted by Bryan Mayland:
Iiiiii don't think so, looking at the datasheet. It looks like that is for the PIC variety of ICSP. I don't know enough about electronics to say what the schematic does. I'm sure they're somewhat similar in function, but this looks like one-way communication with a 13V MCLR signal at the start. The ATmega programming is only 1.8V-5.5V generally except in the case of high-voltage programming with 12V on the reset line.

I don't think it will work, it might, but it would definitely require some technical jiggering.

That stinks. Maybe this one will work? Programmer
 
Originally posted by RJ Riememsnider:
I killed off the cat processes and when I did find -type l | xargs ls -l 2> /dev/null | grep /dev/ttyS0

It came back with nothing.

Guess the ports really are bad.

Something perplexing.... When I loop ttyS1, the router won't boot. It stays at the blinking light. If indeed the rx on ttyS1 were dead, why would it matter if it's connected to tx on ttyS1???
 

Bryan Mayland

TVWBB Hall of Fame
Originally posted by RJ Riememsnider:
Something perplexing.... When I loop ttyS1, the router won't boot. It stays at the blinking light. If indeed the rx on ttyS1 were dead, why would it matter if it's connected to tx on ttyS1???
That really is bizarre especially considering how OpenWrt doesn't do anything with that port normally. This may sound crazy, considering you're one of the more knowledgeable regulars, but are you sure you've got the pinout right on that header?
 
That really is bizarre especially considering how OpenWrt doesn't do anything with that port normally. This may sound crazy, considering you're one of the more knowledgeable regulars, but are you sure you've got the pinout right on that header?


99.9% sure, I've checked it at least 20 times. I soldered wires to tx/rx for S0 and S1 so I can test with all 4.

I have an identical v2 that worked right out of the gate and I built them at the same time.

Also, I have changed linkmeter to use S0.
Loopback on S0 and the router boots.
Loopback on S1 and it does not.
 

J. Winn

TVWBB Fan
I just bought an Uno; I'll use that to flash it. It was about the same price as a programmer and i figured I could get more use out of it than a stand alone programmer. Thanks again!
 

Shane Woessner

TVWBB Member
Originally posted by Bryan Mayland:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Riku Naskali:
How hard would it be to add a feature to automatically shut down the fan when meat is almost at target temp?

Also, is there a downsize to changing the mosfet to more capable and still running the original fan? I'm thinking of making the Linkmeter more universal with bigger fans and pits.
The automatic shutdown is part of the Alarm system that I'm sort of working on. One of the actions you'll be able to configure is a setpoint change.

The MOSFET in the project is good for 60A/60W with an Rds(on) of 0.009 ohms. How much more capable a part are you looking for? I'd be more concerned with the electrical noise of a giant fan switching on and off hundreds of times a second wreaking havoc on the sensitive electronics. </div></BLOCKQUOTE>
A snubber might help in that situation. I'm not sure just a suggestion.
 
Help! Ok, I was an idiot and in a hurry and had a little mishap. Can anyone help me identify the following part on a WRT54GL v1.1?

IMG_20120617_090602.jpg


Looks to be a voltage regulator but I cant read the numbers on it due to letting the smoke out of it.....
icon_frown.gif
 

 

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