Wireless probe board

D Peart

TVWBB Pro
Bryan,
do you have the eagle files for the wireless daughter card? If so would you mind posting it? I'm thinking about making one, even if it is just the schematic, I can do my own board layout.

thanks,
dave
 

Bryan Mayland

TVWBB Honor Circle
You mean the LM Remote module or the RF portion of the HeaterMeter board? The RF portion is just an RFM12B module.

The LM Remote... apparently I do not have a schematic for this. There's just about nothing to it, the big question comes from where do you get your 3.3V to run it.


The 16MHz resonator is optional if you don't mind setting your fuses to 8MHz. The FTDI is optional if you don't need serial output.
 

D Peart

TVWBB Pro
OK that is pretty standard and it looks like I can use my Uno and a bread board to test it all out.

My plan is to use it as my servo controller. With the hopes of getting the software to control the servo added to the HM.

I see a couple ways to get power:
1. Set the fan speed to manual 100% and just use that as a 12V supply and generate the power on the board.
2. Use 4 AA batteries and a LDO regulator to create the 3.3v and a separate 6V for the servo.

I don't know what the run time on the batteries are, but I got to start somewhere.

dave

You mean the LM Remote module or the RF portion of the HeaterMeter board? The RF portion is just an RFM12B module.

The LM Remote... apparently I do not have a schematic for this. There's just about nothing to it, the big question comes from where do you get your 3.3V to run it.

The 16MHz resonator is optional if you don't mind setting your fuses to 8MHz. The FTDI is optional if you don't need serial output.
 

D Peart

TVWBB Pro
Just ordered two of the wireless adapters. One to screw up on and one to use :)

My first goal is to get it working as a temp probe. Then I'll try to expand on that.

dave

OK that is pretty standard and it looks like I can use my Uno and a bread board to test it all out.

My plan is to use it as my servo controller. With the hopes of getting the software to control the servo added to the HM.

I see a couple ways to get power:
1. Set the fan speed to manual 100% and just use that as a 12V supply and generate the power on the board.
2. Use 4 AA batteries and a LDO regulator to create the 3.3v and a separate 6V for the servo.

I don't know what the run time on the batteries are, but I got to start somewhere.

dave
 

Bryan Mayland

TVWBB Honor Circle
Yeah the design is super basic. Just a standard ATmega running on 3.3V with SPI connected to the radio. The main difference between the measuring circuit on this and a HeaterMeter is that instead of the probe just being pulled up to 3.3V, it is attached to a digital line which can be turned on and off to save power.

You can't set the fan speed to 100% manual and also expect to get the automatic fan speed as well because if the PID is running in manual the fan speed is whatever manual is set to. It would be less hokey to just use a power splitter (like a Y-cable) to power them both from the same 12V adapter. The LMRemote code itself can run for months continuously on a single AA battery (stepped up to 3.3V). However, I'm not sure how much that's going to be affected by keeping the receiver turned on all the time but it will be pretty significant. Something along the lines of 15mA vs 100uA.
 

D Peart

TVWBB Pro
I didn't think about setting it to manual mode turning off the PID, but I guess that makes sense :)

Initially I'll just use a separate 12V supply, the Uno and the bread board. When that all works I'll figure out how to power it permanently. I can at least do some testing for current draw and work out what is needed.

Is there a limitation with putting the pit probe on the lmremote card as well? I'm dreaming of a smoker controlled completely wireless so the HM can stay inside the house and not get bothered by the elements.

dave

Yeah the design is super basic. Just a standard ATmega running on 3.3V with SPI connected to the radio. The main difference between the measuring circuit on this and a HeaterMeter is that instead of the probe just being pulled up to 3.3V, it is attached to a digital line which can be turned on and off to save power.

You can't set the fan speed to 100% manual and also expect to get the automatic fan speed as well because if the PID is running in manual the fan speed is whatever manual is set to. It would be less hokey to just use a power splitter (like a Y-cable) to power them both from the same 12V adapter. The LMRemote code itself can run for months continuously on a single AA battery (stepped up to 3.3V). However, I'm not sure how much that's going to be affected by keeping the receiver turned on all the time but it will be pretty significant. Something along the lines of 15mA vs 100uA.
 

Bryan Mayland

TVWBB Honor Circle
You haven't mentioned it so I'll just make sure you're aware that the RFM12B modules are not 5V tolerant so you can't just hook them up to the Uno, you've got to use some of those 4.7k/10k level dividers like the HeaterMeter v3 boards have.

You can put all the probes on the lmremote unit if you want. I had considered this way way long ago, with the blower built into the remote unit as well but had to slap myself because then I was wondering what the point of the HeaterMeter was, if everything was built into the remote.
 

D Peart

TVWBB Pro
OK I had not look at the specs for the RFM12B yet. If that is the case I'll create the 3.3V and run it at that. Then I use the unregulated 6V (from the batteries) for the servo.

If the lmremote has the probes, then the HM has the LCD and controls, or can be used without the lmremote. So I don't plan on it getting too lonely :) I wouldn't want to power the fan with the batteries either, so if I use a fan I'd need to use the HM. If just a servo, then the lmremote should work fine. Hopefully my ramblings make some sense.

dave

You haven't mentioned it so I'll just make sure you're aware that the RFM12B modules are not 5V tolerant so you can't just hook them up to the Uno, you've got to use some of those 4.7k/10k level dividers like the HeaterMeter v3 boards have.

You can put all the probes on the lmremote unit if you want. I had considered this way way long ago, with the blower built into the remote unit as well but had to slap myself because then I was wondering what the point of the HeaterMeter was, if everything was built into the remote.
 

D Peart

TVWBB Pro
Got my wireless transceivers today. I thought you got a pair when you ordered them. Good thing I bought a second (just in case) or else I would only have half a wireless interface :)

next to see if I can get them up and running.

dave
 

Bryan Mayland

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Haha yup just one at a time. Occasionally they show up on eBay too, I got 5 for $4 each with $3 shipping which is a great deal, especially shipped from the US.
 

D Peart

TVWBB Pro
Hmm, I must have bought the wrong RFM12B. I got the 915Mhz one, but it doesn't have that big crystal on it like in your picture. Any problems using this one?

thanks,
dave
 

D Peart

TVWBB Pro
I'm thinking I should have bought the breadout board for this as well, so I could have an easy way to prototype with it and the Arduino. Maybe I'll download the board and see if I can just make my own.

What did you do for prototyping?

dave
 

Bryan Mayland

TVWBB Honor Circle
They make 2 types of the pinless RFM12B. One has a standard size crystal and the other has a little chip crystal. I've used both and they're functionally equivalent. So no worries there!

Before I was making boards, I'd just solder solid core wires (from a chunk of ethernet cable) onto the little indentions. You don't need all the pins, just SDI, SDO, SCK, CS, 3V3, GND and INT. Also solder on a piece of wire for an antenna. For one project I made a little adapter board to break it out onto pinheaders, but that was more trouble than it was worth. I think I printed half a dozen using a laser printer, an iron, HCl, and H2O2 and only one was good enough to work.
 

D Peart

TVWBB Pro
I just ordered the breakout board from Modern Devices. I wish I had looked into that before and I could have saved shipping :)

Got the breakout board today so I hope to be able to get something up and running.

My plan is to get the lmremote sketch ( I think I saw it somewhere ), load it up on my Uno board that will have the RFM12B hooked up via the breakout board (it converts from 5V to 3.3v) and just the little thermistor as a probe. Hopefully I can get that working first then move on.

dave

They make 2 types of the pinless RFM12B. One has a standard size crystal and the other has a little chip crystal. I've used both and they're functionally equivalent. So no worries there!

Before I was making boards, I'd just solder solid core wires (from a chunk of ethernet cable) onto the little indentions. You don't need all the pins, just SDI, SDO, SCK, CS, 3V3, GND and INT. Also solder on a piece of wire for an antenna. For one project I made a little adapter board to break it out onto pinheaders, but that was more trouble than it was worth. I think I printed half a dozen using a laser printer, an iron, HCl, and H2O2 and only one was good enough to work.
 

D Peart

TVWBB Pro
Well I got it up and running, that's pretty cool. I'm using the Vishay 10k thermistor and the remote probe is reading about 22F high. So the Pit is reading 82F and the remote is reading 104F.

I checked my connections, I have the 10k resistor hooked to PD4 the thermistor to PA0 and ground.

AREF is reading between 5.1 and 5.09V.

One other wierd thing. If I touch the thermistor it drops in temperature. I know my body temp is > 82F so that is wierd.

Not sure what is wrong. Ideas on what I can look at?

thanks,
dave
 
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D Peart

TVWBB Pro
Ok I turned on the serial monitor and the NADC values being sent by the lmremote are correct, well closer. It is reading 3892 at 12bit which is 85F so that is only off by 7F. However what is displayed on the LCD is 236F. So I"m not sure why this is the case. I'd imagine it is also linked to the fact that when I change the coefficients the temperature reading does not change.

dave
 

Bryan Mayland

TVWBB Honor Circle
Ah yes if you change the coefficients it should definitely change. Did you change the oversampling bits in lmremote? I haven't tested it with 2. Also let me re-test the latest lmremote code because I have made some changes to the native receiver code so I wonder if I've broken something in the non-native receiver code.

EDIT: You were right! I subtly broke this when adding support for ITPlus with multiple nodes per transmitter. Working code is now up at github.
 
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D Peart

TVWBB Pro
Works beautifully! I was shocked at how easy it was to get this thing up and running.

BTW is there an easy way to just download a single file from github? I always have to download the entire zip, the extract the one file I need.

dave
 

Bryan Mayland

TVWBB Honor Circle
BTW is there an easy way to just download a single file from github? I always have to download the entire zip, the extract the one file I need.
Sweet! Sorry to put you through so much troubleshooting due to my incompetence. You can get a single file from github by replacing "blob" with "raw" in the url:
Github view: https://github.com/CapnBry/HeaterMeter/blob/master/arduino/lmremote/lmremote.ino
Raw download: https://github.com/CapnBry/HeaterMeter/raw/master/arduino/lmremote/lmremote.ino

There's also a "Raw" link on the top right of any source file, which is how I remember how to do it.
 

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