The messages related to the coolbox are detected for message ID’s 0x01, 0x02 and 0x04. I associated message ID 0x01 with the Touch screen operating display and in case of the coolbox this message ID contains the setting of the cooling level of the coolbox. Message ID 0x02 and 0x04 may be associated with a nugget electronics box under the kitchen. Both contain temperature sensor information as well as other state information. It is actually a mixed bag. First lets focus on the coolbox:
ID = 0x01 contains the coolbox level in data byte 1 (second byte) but in its high nibble (actually bit 4 and 5). ID = 0x02, byte 4 contains temperature sensor data and in ID = 0x04 byte 1 contains a bit that is high when the compressor runs (bottom trace). The graph aggregates a couple of values, but actually the yellow line consists of values 0 and 2 (only). Not displayed but actually there is a copy of the temperature sensor in 0x04, byte 4. Due to a imprecise Thermometer it took me a while to figure out the relation to the red signal (byte 4 of 0x02) and the actual temperature. There are actually two possibilities. The value is a measure of the resistance of the NTC or it is already in the temperature domain. When using a more precise thermometer in the above runs and also using some datapoints collected over the weeks before when the fridge was off, using the inboard temperature reading I could make a fit between byte values and observed temperature in the fridge. The relationship was simple and very linear. This discarded the hypothesis that it would be resistance values.
When reducing the number of decimals in the fitted equation it simply reads y=-x+25 or T=-(B4) + 25. Using this conversion we get this relation between byte 4 value and the coolbox temperature:
Performing some more measurement we can see that the coolbox uses about I=5A when the compressor is running.
Next to the observation that byte 1 (u41 in graph) in message 0x04 contains a bit that indicates the compressor is running, there is a bit that shows the opposite behaviour: byte 3 (u43). Coolbox level in the top right is the decoded byte 1 of 0x01.
The byte 3 of 0x04 contains some more status bits. Those are related to the ignition state of the car part of the nugget. Bit 2 is indication that the engine is running while bit 0 reflects that the contact of the car is on (0 = on). Byte 0 of 0x04 are also indicating the car contact is on and the engine is running. I expect that 0x04 contains some more information on the electrical pathways in the Nugget, but due to may Camper battery condition I can not test it at the moment.
Finally 0x02 contains the sensor data for the outdoor and indoor temperature sensors as displayed on the touchscreen. And I have found some water tapping related bits in 0x01 and 0x02. Below is the current state of knowledge on those 3 message ID’s:
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? Touchscreen central controller ?
ID : 0x01
data: 00 30 00 00 00 00 00 00
| | | | | | | |
AA | | | | | | | = b0: 0.4-0.5s high when operating display
| | | | | | | b1: waterpump 0=off 1=on
CB | | | | | | = High nibble (b5,b4): coolbox level setpoint 0-5
?? | | | | |
?? | | | |
?? | | |
?? | |
?? |
??
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? Central controller (sensors?) ?
ID : 0x02
data: 5C 5F D7 D7 0B 03 00 00
| | | | | | | |
TO | | | | | | | = T-outside ((120-x)/2 °C)
TI | | | | | | = T-inside ((120-x)/2 °C)
?? | | | | |
?? | | | |
CT | | | = T-coolbox (25-x °C)
GF | | = Water level indicators Grey and Fresh water values 0-5
HH | = 0x40 for 0.4-0.5s when menu operated.
AA = b0: watertap 0=closed 1=open
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? coolbox + car signals ?
ID : 0x04
data: 00 02 00 (mostly 3-byte frames)
data: 00 00 00 3B 13 00 00 01 (periodically 8-byte frames)
| | | | | | | |
AA | | | | | | | = 0x01 car contact on 0x05 car engine running
CS | | | | | | = Coolbox compressor running 0x00 off, 0x02 = on
?? | | | | |
BB | | | | = normally 0x3B, 0x36 car engine running
| | | | b0: 0 = contact on
| | | | b1: 1 = coolbox compressor runs
| | | | b2: 1 = engine running
CT | | | = Coolbox temperature sensor. same as ID 0x02 CT
?? | |
CC | = 0x40 for 0.4-0.5s when heater setpoint changed
??
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