Finalize HM 4.1?


 
D

Dave Casazza

TVWBB Fan
Hi Bryan, & hardware guys,

We are looking to release a version of the boards that separates out the rPI/HM function and the servo/thermometer functions by Cat 5.... (keeping the rPI out of the rain).

Have we finalized what the HM4.1 design would include, so we can publish our work that would align well with HM4.1?

Thanks,

Dave
 
I have not even done the first test board yet so I can't really say what's going to work and what isn't. Still at least a couple of months away.
 
Hi Bryan,

Any word on what incremental features you plan over HM4.1? Would love details to get up to speed quickly, and in parallel.

Thanks,

Dave
 
This is the list of possible features TODO. Some things like "Integrate switching power supply into PCB" are a 90% not going in though.
 
Dave Casazza said:
Hi Bryan, & hardware guys,

We are looking to release a version of the boards that separates out the rPI/HM function and the servo/thermometer functions by Cat 5.... (keeping the rPI out of the rain).

Have we finalized what the HM4.1 design would include, so we can publish our work that would align well with HM4.1?

Thanks,

Dave
Click to expand...

Have you given any thought to the possibility of using a wireless connection between the inside and outside units instead of a CAT5 cable? I know that would require a power supply (or large battery) to be outside... but right now I have my servo and blower connected through a CAT5 cable which I can certainly make long enough to bring the entire HM indoors, (and could use RF for the pit probe) so I don't see the benefit of having an inside and outside board unless they connect together without a wire. The only benefit I could see to splitting the boards over what I have now is you could use all 4 probes, but my CAT5 cable still has 3 spare wires right now that I could use to connect the probes (4th wire will be available when the new HM board comes out with the different MOSFET that switches the + voltage to the fan so it can share a ground with the servo), so I think what you are doing can already be accomplished without any hardware changes?

If the unit out at the grill could interface the probes, fan and servo and connect to the main HM without a wire then you'd have something.... My idea, which I have mentioned before, was to use two HM boards and populate one with the components to control the blower and servo and read the probes. and a second HM board with the components to interface with the rPi (or possibly be a complete HM unit so it could work in a stand alone fashion as well), and have these two unit communicate wirelessly. Both units would need to have a processor, the unit at the grill would essentially be a stand alone HM with the addition of a wireless device that allows it to communicate with the base HM unit. The unit at the grill would essentially get its marching orders (pit setpoint) from the main HM , but would run the pit on its own, so if the wireless connection faltered the main HM unit would only have dropouts in temp readings but the standalone HM at the grill would still be holding the pit at the setpoint. (one of Bryan's concerns was what if the main HM unit lost communication with the grill unit).
There would have to be a different HM code written for the grill side unit and I know Bryan is reluctant to take that on, but it seems pretty doable (and logical) to go this route to me. I would think it could be done in a way that the same HM board be used for the main HM unit (connected to the rPi) and the unit out at the grill, which would be a plus, instead of needing a custom board for the grill side and the rPi side... Just thought I would throw that out there...
 
Last edited:
I'm not proposing anything that isn't compatible with Bryan's code base, present or future. That's not something I'm anxious to take on. :)
 
Dave Casazza said:
I'm not proposing anything that isn't compatible with Bryan's code base, present or future. That's not something I'm anxious to take on. :)
Click to expand...

Well, damn.... I keep pushing on that idea cause I think it is a good one, perhaps one day you guys will arrive at the same position and it will happen....

That idea aside, how is what you are working on better than just using the CAT5 cable I/we have now to run the servo, blower and connect the probes? It seems that can all be done with the 8 wires in a CAT5 cable (in theory, I've never actually connected the probes through the CAT5 cable). I will probably wire up the probes to the CAT5 cable before winter sets in, but that brings up why I really wanted it to be wireless, cause I can't see leaving a door or window cracked open in the winter to let the CAT5 cable in.
 
Hi Ralph,

The way the HM 4 architecture is structured, if we required no code changes, we would have to set up an emulator layer on both the remote wireless card and the HM4 mainboard. Analog temperature channels would have to be digitized on the wireless remote, then transmitted, then converted back to analog value to be re-processed by HM4. Likewise, blower out on HM4 would have to be PWM decoded, converted to digital, transmitted, then converted back to PWM on the remote card. Lots of work, and likely non-trivial (in engineering parlance).

Oh, and then we need power on the remote to drive the PWM & Servo (if desired). That's at least one wire you have to run outside, unless you have a outside plug and/or battery. (Just sayin....)

It would be easier if we adopted a shield model for HM4 (add another shield for wireless support), but... we don't have that.
 
Last edited:
Dave, aren't the analog temperatures converted to digital before they are passed on to the rPi? If so, with a standalone HM the digital temps are just going nowhere? So isn't it possible to use a stand alone HM at the grill and have the digital temps sent via wireless to the main HM that has the rPi? (perhaps not without some coding, but it could be done, right?) If the standalone HM was controlling the pit you wouldn't need to convert the fan/servo data to digital at all, you would just need to transmit the setpoint from the HM+rPi to the standalone HM I would think, from there the hardware on the standalone HM could manage the blower/servo to hold that setpoint.....

I realize this isn't doable with the existing code, but Bryan had been working on the wireless probe concept already... I thought perhaps a wireless standalone HM would be more useful and perhaps more worth the time than a wireless probe... cause after all, if you have a wireless probe you still need a HM board at the grill to control the pit.

As for power, yah, you are always going to need power at the grill and therefore at least 1 wire. But having to plug in the controller at the grill isn't a big deal, and I had given some thought to using a battery and solar cell to recharge it, which would give you a completely wireless grill connection....

As far as working with existing code, what I have come up with is to just use a cat5 cable from the HM+rPi and use the 8 wires for:

Servo Signal
Servo/Probe(s) Ground
Servo +5
Blower Signal
Blower +12
Probe 1
Probe 2
Probe 3

This will theoretically run the whole pit with 3 probes over 1 cat5 cable, though I haven't tried connecting any probes over the cat5 cable yet. I just ordered some 2mm panel jacks that I am gonna wire to the CAT5 jack on the grill side, so I can plug the probes in there, then jumper those three CAT5 wires over to the probe inputs inside the HM, at that point I will be able to test the concept. Still have to get that cable into the house for winter cooks though, but don't want to leave a window or door cracked open.....
 
Last edited:
Hi Ralph,

Re Wireless: All of this will require re-factoring/re-coding on someone's part. I’m not volunteering to fork the code (talk about a nightmare, and I've been associated with the software dev business for my adult life). Talk to Bryan?

A fallback is to use some cabling to get the valuable stuff out of the winter weather. You are on the right track.

As a final thought:

If you want to suggest making changes of this type, develop a framework where the software has an API to write to hardware (a contract agreement, of sorts). Then if you want to innovate hardware, as long as you meet the API "agreement", it will work.

If the HM4 328P software supported a secondary command bus, that was digital in nature, you could probably easily serialize that and send/receive it (blower and therms data) wireless to some other remote device. We have already done that in a sense, with just wireless therm monitors.

Bottom line - gotta bring Bryan into this convo, bud.
 
Last edited:
I understand, and I try not to push, perhaps just nudge... I figure I will throw out my ideas, then as this HM evolves at some point the changes and the coding work might make sense (to Bryan) and it may happen. I know he had been working on a wireless module but scrapped his first draft design, so perhaps instead of working that development path he may take my idea to make two HM boards communicate and develop in that direction. I figure Bryan reads all this and is taking in the suggestions, from there it is up to him, cause unfortunately I don't do coding....
 
Why not just use a wireless rs232 kit, like this one on ebay? That would require no rework of the code, as communication between the HM & Pi is still standard serial communication. You already have the supply voltage at each end.This has the advantage of having the actual HM board at your cooker, communiction interuptions wouldn't jeprodize your cook.
 
Brian Hilgert said:
Why not just use a wireless rs232 kit, like this one on ebay? That would require no rework of the code, as communication between the HM & Pi is still standard serial communication. You already have the supply voltage at each end.This has the advantage of having the actual HM board at your cooker, communiction interuptions wouldn't jeprodize your cook.
Click to expand...


Huh? How do you send voltage for the servo and fan, and resistance from the probes over a wireless serial interface?
 
RalphTrimble said:
Huh? How do you send voltage for the servo and fan, and resistance from the probes over a wireless serial interface?
Click to expand...

You run the HM board at the smoker, and transmit via wireless serial back to the PI. You lose the benefits of having the HM board connected directly to the PI, but you gain the ability to keep your PI inside, no wires through doors or windows. You still have to supply 12V at the HM, and now have to supply 5v to the PI (standard USB charger), but there is no longer a need to have the two tethered to each other via wires. I just looked at the one I linked again and saw the astronomical shipping fee, but a search on ebay for wireless serial or wireless rs232 reveals several other options at a more reasonable price with shipping.

When I said you have the supply voltage at each end, I was referring to the fact that once you have initial supply (12v at HM, 5v at Pi) that both boards have voltage regulators to get you to 3.3v or 5v, depending on the transceiver pair you chose.
 
Last edited:
The raspberry pi is $25 or $35 depending on the model that you get. It seem that separating the components is a lot of work for the amount of gain that there is. I like the idea of using a CAT5 cable and it seem that that is already being done by some for the blower and damper. I personally would like to get the thermocouple design advanced.
 
You must log in or register to reply here.

 

Back
Top