Bradford White GEA2 | Home Assistant | Page 1

wheat abyss Aug 31, 2024, 2:31 PM

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I got one of these https://amzn.to/3yQVAWT and measure the voltages (I don’t have an oscilloscope or signal analyzer)

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From left to right on the terminals I numbered them as 1 to 8

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Between 1 and 3 there was ~ 7.22v

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Between 1 and 7 the voltage seemed to bounce between ~9 and 12v

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Between 1 and 8 there was a constant ~12.2v

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This is with the heater (heat pump) running

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8 seems to be ground

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7 seems to oscillate between voltages

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Terminals 3 and 7 bounce between 3 and 5v

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Terminals 3 and 8 is a steady 5v

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The rj45 terminal block is wired 568b per the description

fallen chasm Sep 1, 2024, 3:30 AM

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Nice, that seems to match what I'm seeing; I have a very basic Python script setup to send a single broadcast packet via an inverted Arduino software serial interface. I think I should have some time tomorrow. Hopefully I can get a response on one of the 0V pins.

For reference, this is what I measured (rounded to whole volt):

pin 1: GND
pin 2: 0V
pin 3: -7V
pin 4: 0V
pin 5: 0V
pin 6: 0V
pin 7: -12V
pin 8: -12V

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Could be we have some differences, as I see in the bottom-left of my control panel 238-52365-00, whereas yours is 238-54366-00....

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You may have a newer revision

wheat abyss Sep 1, 2024, 10:28 AM

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I don’t think the connect device has changed so I doubt the communication between them has either.

fallen chasm Sep 1, 2024, 4:35 PM

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I'm not sure I follow your measurements; you say you're measuring between pins 1 and X, but then say pin 8 is ground?

wheat abyss Sep 1, 2024, 5:15 PM

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Measuring with negative on pin 8 and positive on Pin 1, I get 12v.

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1 is likely ground I don't know why I thought 8 was

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for pin 7, it definitely jumped between 9 and 12 volts

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pin 3 was 5 volts

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and when measuring between 3 and 7 it jumped between 3 and 5v

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will try and take a look in the connect later today or tomorrow.

fallen chasm Sep 2, 2024, 1:57 AM

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I ordered the same terminal you have. Mine should be here tomorrow, so I can stop using my ghetto cable haha

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I do wonder if you're on to something, I'm seeing -12V and -7V when I test with GND as pin 1. I wonder if I'm looking at it backwards. The photo of the board I shared earlier shows that it should be +5V (and presumably +12.3V), so what I'm seeing with the scope doesn't really make sense

fallen chasm Sep 2, 2024, 9:40 PM

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Hm, I may have to wait to see what you find probing your wifi module. I've sent a broadcast packet over all 0V lines and haven't received a single response. Kinda stumped myself.

Packet looks like:
E2 FF 08 BB 01 9A 85 E3

E2 packet start
FF packet dest (broadcast)
08 packet length (bytes)
BB packet source/sender
01 read firmware version
9A CRC MSB
85 CRC LSB
E3 packet end

fallen chasm Sep 2, 2024, 11:29 PM

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Okay, good news! Pretty sure I figured out there the data pin is. I think you were right, pin 8 is ground, but pin 7 seems to be acting as the data pin for me. I'm getting a response!

Weird part though... the water heater is only signaling at 1V... Not sure what the deal is with that. Any thoughts @vague ravine ? It looks like a valid GEA2 packet, just... 1V for some reason, haha.

The 3 screenshots I sent are, in order:

The packet sent by my Arduino
Both packets
The response from the water heater

Arduino packet:
E2 FF 08 BB 01 9A 85 E3
Water heater response packet:
E2 BB 0C 60 01 04 09 04 16 CB A0 E3

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I can see the packet on the scope, but of course the Arduino isn't seeing it b/c the voltage is so low

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Note: I rescaled the voltage to 330mV per division in the 3rd screenshot

vague ravine Sep 3, 2024, 5:25 PM

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Can you double check the ground connection against chassis ground? Maybe it's just a lower voltage and the 1V is relative to it, not ground?

fallen chasm Sep 4, 2024, 1:27 AM

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vague ravine Can you double check the ground connection against chassis ground? Maybe it's ju...

Hm, I think it must be isolated.
All 8 pins read 3-4 MΩ to chassis ground

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I may have to take the top housing apart again so I can expose the control board I shared the picture of before. That way at least I can be sure I'm on GND

fallen chasm Sep 4, 2024, 2:09 AM

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That being said, I'm relatively confident I've identified GND. With GND as pin 8, I'm getting a clean 5V and 12.2V to pins 3 and 1 respectively.

I'm also only able to get any response from pin 7 with pin 8 as GND, only at 1V

fallen chasm Sep 4, 2024, 4:45 AM

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So I shut off the breaker, opened the control panel, and did some continuity testing with my multimeter. I can confirm 100% that:
pin8: GND
pin3: 5V
pin1: 12.3V

However, pins 2, 4, 5, 6, and 7 don't appear to be connected to anything I was able to probe from the back PCB (and I spent a good hour or more looking). I would have thought they'd be connected right in the same place as the 3 pins I mentioned above, but that doesn't seem to be the case.

fallen chasm Sep 4, 2024, 3:34 PM

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Is GEA1 also 5V? Everything in the docs on this heater says it should be GEA2, but kind of grasping at straws at this point, haha

wheat abyss Sep 4, 2024, 4:00 PM

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I haven't had time yet to pull down my bwconnect box (it's mounted to the ceiling above the water heater) to open it and probe voltages inside it yet. still on my todo list - I started to do it last night but crashed after getting less than 4 hours sleep the night before. 😬 .. stuck in office until later today.

fallen chasm Sep 4, 2024, 4:34 PM

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No worries, definitely more of a weekend project, hehe

fallen chasm Sep 4, 2024, 6:32 PM

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Well, I may not be getting 5V back from the board, but I sure can write to it!
https://services.pyrahex.com/public/videos/tmp/water_heater.mp4

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This document seems to be pretty accurate for the Bradford White as well:
https://github.com/doitaljosh/geabus-documentation/blob/master/hewh-interface.docx

Everything I tried responded as expected, even though I had to use the scope to see it lol

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Apparently you can get pretty wild and directly control the compressor, heating elements, etc. I think I'll stay away from that though, haha

wheat abyss Sep 4, 2024, 6:35 PM

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wow. have you seen this? > https://github.com/mulcmu/esphome-ge-laundry-uart would be cool to get this into an esphome component

fallen chasm Sep 4, 2024, 6:36 PM

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The document makes it sound like you can even set the temperature above the normal lockout, to where it will actually make it hit the thermal cutout

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huh, I haven't seen that. I'll check it out

wheat abyss Sep 4, 2024, 6:48 PM

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So does it seem like BW uses same commands etc as the GE? that doc is a map to everything if so. for me most important is mode and temp control, and energy monitoring.

fallen chasm Sep 6, 2024, 1:57 AM

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Yep, seems to be that way. I'll probably hold off on working on it too much more until I can figure out why I'm only getting 1V back from the water heater. I'll be interested to hear what level the BWCAdapter is running at when you have a chance to check that out.

If It should only be 1V, I need to get a logic level convertor or something to avoid overdriving that pin. Also to actually receive responses without having to use my scope, haha

wheat abyss Sep 7, 2024, 6:46 PM

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I did not do much probing but this thing has test points every where . Pics from multiple angles for best light to see traces. Posted in Imgur so not as bad compression https://imgur.com/a/qM5SQTD

Imgur

Untitled Album

vague ravine Sep 7, 2024, 7:45 PM

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Interesting, it has two optoisolators like the other Beans

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And a straight up ESP32 module 😄

fallen chasm Sep 7, 2024, 10:10 PM

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Nice. I'd definitely be interested what pins it's using to talk to the water heater, and at what voltage they're talking

fallen chasm Sep 7, 2024, 11:01 PM

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It's interesting that they have pins 1, 2, 7, 8 circled on the back. If it matches up to what I've measured:

1: 12V
2: unknown
7: DATA
8: GND

Not sure what pin 2 is for, I couldn't get any communication on it, and it isn't carrying any voltage like pins 1 and 3

fallen chasm Sep 7, 2024, 11:20 PM

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Of course, that's assuming they are numbering in order with the RJ45 connector, haha

wheat abyss Sep 7, 2024, 11:20 PM

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I’ll check that.

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The connect box is powered by 5v in the little bit of probing I did I don’t think I saw anything over 5

wheat abyss Sep 8, 2024, 12:38 AM

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1,2 & 7,8 match our original numbering: #1279229546608066611 message

fallen chasm Sep 8, 2024, 1:03 AM

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I think 5V is on pin 3 though

wheat abyss Sep 8, 2024, 1:04 AM

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the whole pin order matches.

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there was one test point that had alternating voltage. i'm trying to trace it now.

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majority ot TPs were 3.3v

wheat abyss Sep 8, 2024, 1:31 AM

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this is only thing I've been able to trace so far:

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progress with 7 and 3:

fallen chasm Sep 8, 2024, 1:52 AM

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Interesting that pin 7 seems to connect through C29 to GND on that optocoupler
https://rocelec.widen.net/view/pdf/rwjc9al1ln/ONSM-S-A0003590761-1.pdf?t.download=true&u=5oefqw

wheat abyss Sep 8, 2024, 1:52 AM

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pin 8 does too.

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as far as I can tell 3,7,8 are the only pins passed through to the board

fallen chasm Sep 8, 2024, 1:55 AM

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My brain doesn't do so hot with circuits, but it seems odd that pin 7 and 8 are set up that way.

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Looks like maybe pin 7 is controlling current flow from pin 3 via that (transistor?) before R41?

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Not sure I know what I'm looking at tbh, haha

wheat abyss Sep 8, 2024, 2:05 AM

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yeah this is a little over my head as well. a bit more going out from the optocoupler pins... hurts my head.

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fallen chasm Sep 8, 2024, 2:07 AM

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You know, we have all these lovely 1-wire protocols out there... why can't they use something normal, haha

wheat abyss Sep 8, 2024, 2:08 AM

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I'm getting some of the boards from this project made. #1279229546608066611 message

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they say it supports gea2 so figure what the heck.

fallen chasm Sep 8, 2024, 2:10 AM

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It does look like the water heater side is tied into the emitter side of the top optocoupler, and the detector side of the bottom one. Makes sense they set it up that way to split up send/receive.

No clue what all the crap to the left of that is doing, haha

fallen chasm Sep 8, 2024, 2:11 AM

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wheat abyss they say it supports gea2 so figure what the heck.

Can't hurt to try

wheat abyss Sep 8, 2024, 2:11 AM

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I think it is all ESD protection

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interesting they have 1, 4,5, 7, 8 in play

fallen chasm Sep 8, 2024, 2:13 AM

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I think GEA2 can be full-duplex, but it sure doesn't look like this water heater is

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Ah yeah, it says there

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7 is halfdplx, 4&5 are fulldplx tx/rx

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Damn, that document is excellent actually

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Interesting, I wonder if I can get what I need with just a cap and 2 diodes...

wheat abyss Sep 8, 2024, 2:16 AM

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I should have the boards in a 10 days or so, they sent me questions including a photo so pretty sure they are done production , I didn't get fast shipping though, and have to get a few components still.

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I think I'll have 5 in total so will be happy to send one.

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the ge dryer is half duplex and this was the guys test setup. https://github.com/mulcmu/esphome-ge-laundry-uart/blob/main/dryer testing.jpg

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buck converter, resister and one of these - https://www.dfrobot.com/product-2285.html

Fermion: TXS0104E 4-Bit Level Translator (Breakout)

This 4-bit non-inverting translator uses two separate configurable power-supply rails.

fallen chasm Sep 8, 2024, 2:44 AM

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wheat abyss I think I'll have 5 in total so will be happy to send one.

I appreciate the offer! I'd like to keep digging to understand all this a bit better though

fallen chasm Sep 8, 2024, 2:45 AM

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wheat abyss the ge dryer is half duplex and this was the guys test setup. <https://github.co...

Hm, that looks about like what I'm doing with the Arduino, although I don't have the logic level converter since both (should be) talking at 5V

fallen chasm Sep 8, 2024, 3:08 AM

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I'm just stuck on why I'm only getting 1V from the water heater. Looking at all these example builds, I'm not seeing what is pulling that signal level up to 5V. Unless something is damaged on my water heater board? Kind of at a loss

fallen chasm Sep 11, 2024, 4:44 PM

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I went ahead and ordered a few logic level converters from Adafruit, I should be able to try that out this weekend. If for whatever reason the water heater is still talking at 1V (maybe something on the Arduino is pulling it low for some reason?), maybe I can at least use the converter to talk to it at 1V (it's only rated down to 1.2V, but I'm grasping at straws, haha)

https://www.adafruit.com/product/1875

vague ravine Sep 11, 2024, 5:02 PM

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Does the bus read 1.2V even when the Arduino is disconnected?

fallen chasm Sep 11, 2024, 5:23 PM

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I haven't tried that yet. I could probably test that with a simple voltage divider.

My plan was to try using the converter with Pi 3.3V -> water heater 5V. Using it more as a way to try to isolate whatever the arduino/pi is doing with pull-up/pull-down.

If I still see the water heater talking back at 1V, then I'll try dialing down that side to talk at 1.2V and see if that gets me by

fallen chasm Sep 11, 2024, 5:26 PM

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vague ravine Does the bus read 1.2V even when the Arduino is disconnected?

Oh, I may have slightly misread your question. The bus never shows any traffic unless I poke it with a valid GEA2 packet first

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When I send a valid packet using the Arduino at 5V, I get a response back at almost exactly 1.0V

vague ravine Sep 11, 2024, 5:35 PM

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What if you interact with the water heater via its buttons or knobs or something?

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With my washer at least, every button and knob triggered a message

fallen chasm Sep 11, 2024, 9:02 PM

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I didn't see anything when I was testing before, but maybe that was before I was using the scope. Lemme give that a try

fallen chasm Sep 12, 2024, 3:52 AM

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Nope, I poked every button on there, but no GEA messages. Not sure if it's an external vs internal bus thing? I'm hooked up to the external bus on the RJ45 connector.

I did look a little closer at the responses to the Arduino's messages, and they're actually more like 0.8V

vague ravine Sep 12, 2024, 3:12 PM

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Hmmm. What about if you power cycle the heater?

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0.8V and 1.2V are really odd signaling voltages

fallen chasm Sep 12, 2024, 3:43 PM

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I can try that. 1.2V is the minimum rated voltage on the logic level converter I ordered, I'm not seeing that on the water heater

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That's why I ordered the logic level converter too: to see if adding some isolation between the Arduino and water heater might show a different result. Like, maybe something on the Arduino is pulling that voltage lower than it should be?

I'm using the SoftwareSerial library with inverse_logic set to True. Maybe the Arduino's pull-down is too strong? Just spit-balling

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I could also use a much shorter cable and test the voltage. I think I've been testing with a 3m cable so I can have my laptop set on the counter.

vague ravine Sep 12, 2024, 4:03 PM

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From what I recall, the bus has a global 4.7K (or 47k?) pulldown and individual devices pull it up to signal

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Looks like for mine it was 4.7K. If the bus is nominally 3.3V, you'd need a ~1K pulldown to drop it to 0.8V. With a 5V bus, it'd be 1.5K.

fallen chasm Sep 12, 2024, 5:51 PM

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Not really seeing anything different after the power cycle

#Bradford White GEA2