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TimRegeant
@TimRegeant
then use 'interceptty' command to set up a pseudo-tty and sit in the middle to pass back and forth between the serial port and pseudo-tty. This allows the traffic to be monitored.
no I passed "hello world" to the heat pump
*now
echo -en "hello world" > /dev/intercepttydummy
the heatpump UART echoes back the same thing. So then I pass the connect string
echo -en '\x00\xfc\x5a\x01\x30\x02\xca\x01\xa8' > /dev/intercepttydummy (-en = enable backslash interpretation and do not output trailing newlines)
However, the heatpump just echoes back the string. I am using Gtkterm connected to the pseudo-tty and see what is coming in from the serial port.
TimRegeant
@TimRegeant
Any thoughts? Is this the right connect string?
TimRegeant
@TimRegeant
hello? taps microphone Is this thing on? Anyone out there? :)
SwiCago
@SwiCago
No clue, never used a PC to talk to the heatpump. Started with an oscilloscope and the went directly to esp8266
TimRegeant
@TimRegeant
Oh I understand, I can hook my scope up and go that way also. Might need a little help to get up to speed with it again. Could be a few days before I can get back to the project. Have a good one!
SwiCago
@SwiCago
@TimRegeant what is it you are trying to figure out?
TimRegeant
@TimRegeant
Ok, made a little headway. RS232 is inverted from what microcontrollers use so I took out the scope to look at the waveforms. A little backstory. I have the MHK1 remote thermostat for my heat pump. The wireless portion connects to the CN105 connector and controls the heat pump based on the remote thermostat portion. The problem is that even when the compressor is off, the fan always blows. This is a design problem with these Mr. Slims when used in a single room since the moisture on the coil blows out in the room and the humidity gets very high. Soooo, I want to put an arduino between the CN105 connector and the wireless transceiver to intercept the messages and turn off the whole unit when the packet to turn off the compressor is sent and vice versa when it is time to turn it back on. Should be simple enough.
TimRegeant
@TimRegeant
So I made a jig to hook the Rx line of CN105 to the scope to see how the wireless transceiver sets up. This is without the remote thermostat active. The pulse width is 400us so 2400 baud. Looking at the waveform, is it 8E1. When the transceiver is turned on this byte sequence is sent "0xFC, 0x5B, 0x01, 0x30, 0x01, 0xC9, 0xAA". This was verified several times. With the remote thermostat off, the transceiver portion sends the following two sequences over and over: "0xFC, 0x42, 0x01, 0x30, 0x10, 0x04" and "0xFC, 0x41, 0x01, 0x30, 0x10, 0x07, 0x00, 0x00".
Looking at your code, what I would interpret as the connect string (the first byte sequence) is a little different from what you are sending. Could be because I am using the MHK1? Does anything stand out in any of the 3 sequences?
Adam Jobbins
@ajobbins_twitter
The problem is that even when the compressor is off, the fan always blows. This is a design problem with these Mr. Slims when used in a single room since the moisture on the coil blows out in the room and the humidity gets very high.
Huh - that may explain the damp smell we sometimes have with our units when they are in cooling mode. Ours aren't Mr Slim but MSZ-GE units, but the fan always runs regardless of compressor state
SwiCago
@SwiCago
@TimRegeant i mentioned this somewhere in the past when I did packet dumps with kumocloud. Then connect string HP library uses is a universal one. There are many. Each one has represents a specific model HP. When the HP responds, the device(mhk1,kumocloud) knows what type of HP it is and knows what it is capable of. Since we do not know every possible unit type, we use universal connect. We already know what we have and what it can do. As for you issue, turning fan off when temp is reached/compressor off is done via jnstaller settings. I have recently discovered that updated kumo cloud app lets me change these settings, so I plane to packet dump all installer settings as soon as I get a few things finished at my house. Installer settings lets you change set points, fan function, min/max temp etc.
If you do discover a packet sequence, please post in #39
I personally never ran into the humidity issue, as I have setup my automation to turn off the unit once it reaches temperature offset I define and turn on again when a upper offset is reached. But having fan auto off would be better. If you don't discover it, don't worry about it. I will be soon getting back into this. Cheers
TimRegeant
@TimRegeant
@SwiCago Hi, the installer options for #101-128 are not available through the MHK-1 for ductless units. My understanding is they are only for ducted units. The fan off installer option when the set point is reached for heat is 125 and for cool is option 127. Options 101-128 are sent by the heat pump to the remote thermostat so vary by heat pump model number.
TimRegeant
@TimRegeant
Here is the installation manual for the MHK-1. It lists the installer options on pages 6 and 7. Might help with the packet dumping with the kumo cloud app. http://www.rfwel.com/downloads/MRCH1.pdf
TimRegeant
@TimRegeant
I found a hardware solution. Turns out the options which are locked-out from the M-series ductless units are hardware through a jumper block on the control board. Removing the JRRE resistor cuts off the fan with the compressor in cool mode and removing the JR01 resistor cuts off the fan with the compressor in heating mode. This works with my unit so I'm good now. ymmv, but if it's a feature you need, then this might be an option for you.
alt
alt
SwiCago
@SwiCago
@TimRegeant interesting hardware solution
mihalski
@mihalski
I've just stumbled upon this phenomenon (awesome! thanks to all involved) and wanted to start ordering parts.. just wanted to confirm that these make sense
as far as I can tell I should be able to just push these pre-crimped cables into the connector and plug the connector in.. have I chosen the correct parts?
SwiCago
@SwiCago
On the main page of the project there is a link to prefabbed cables for $1.99 each http://www.usastore.revolectrix.com/Products_2/Cellpro-4s-Charge-Adapters_2/Cellpro-JST-PA-Battery-Pigtail-10-5-Position
mihalski
@mihalski
yes and the shipping to AU is I think $15 :P
as opposed to FREE for rs-online
mihalski
@mihalski
Screen Shot 2019-10-11 at 7.31.46 pm.png
vs
Screen Shot 2019-10-12 at 8.54.36 am.png
revolectrix isn't even including the cost of the items themselves
and the $17.16 includes 10 connectors and 10 wires.. plus shipping takes just a few days rather than a couple of weeks. My only concern is whether the parts are correct
mihalski
@mihalski
I could have sworn that I saw a Wemos with a connector of the correct pitch somewhere in the issues.. Can't find it now..
mihalski
@mihalski
@TimRegeant I can't see JRRE anywhere on the diagram for my system
Screen Shot 2019-10-12 at 3.04.31 pm.png
you need to be in the US to access it.. I used a VPN.
mihalski
@mihalski
JRRE:Fanspeedwhilethermaloffin cooling
• Jumper on: Determined by the remote controller
that does imply that it should be possible to control via CN105
Screen Shot 2019-10-12 at 5.27.12 pm.png
All the discrepancies are somewhat confusing
and if my board is like the one from the original article then it doesn't even have a jumper at JR19/JRRE.. https://nicegear.nz/obj/blog/heat-pump-hacking-2.jpg
TimRegeant
@TimRegeant
I found my information here: https://www.reddit.com/r/HVAC/comments/7y99p4/mitsubishi_wall_mount_minisplit_with_mhk1/ It's not much to go on, but it worked for me. My understanding is some of the settings are sent by the heat pump and if the heat pump doesn't send them, they aren't available to change. For example, my MHK-1 remote thermostat doesn't even give install options for 101-128 as the installation guide shows because my heat pump doesn't support them. So I can't set those through the remote thermostat hence I had to cut the resistors. Here is a picture of the unavailable options from my heat pump. alt Your heat pump may be (likely) different than mine. Somewhere I read the ducted units can be software configured for the fan and the ductless could not. You're right it is all a little ambiguous. That is on Mitsubishi.