Dishwasher controller

[Simon]

This is not a repair as such but I want to reverse engineer the connections to the controller in my indesit ICD661 dishwasher so that I can run my own wash programs on my own controller controlling the various bits of the dishwasher

[shakalnokturn]

http://servicenet.indesitcompany.com/data/img_sm/sm46741.pdf

Although I understand the point in wanting to do that, an Indesit seem like a poor mechanical base to build your own electronics onto...

[Simon]

Well at the moment it takes too long to wash and it's what i have. I don't care for the drying cycle that requires salt that now is being gobbled up by the machines and left dirtily on everything it "washes" so time to hack it.

The is a box in the base with a PCB in it and cables from every device in the machine so should be fairly easy to just take control of each device.

I just want to run as hot as i can for 10-20 minutes and done. None of this running at 50-70 for 2 hours. Industrial machines do it and don't need detergent.

[floobydust]

Writing your own dishwasher firmware is a little hairy, there is safety to think about with leaving a heater or fill solenoid on. You have to filter and debounce all inputs, and have timeouts if a switch or float gets stuck, pump doesn't work, that kind of thing. But nothing an Arduino couldn't pull off
The controller board looks straightforward, I would see if it's possible to read the dishwasher MCU's firmware and disassemble it.
Just need to post PC board pics and sketch a schematic to assign I/O, the MCU seems to have only 16 pins.

[NivagSwerdna]

Drop your insurance a line and let them know you are running your own dishwasher firmware... I'm sure they will be interested!

Make sure you use a Watchdog timer and try and fail safe!

[Simon]

Drop your insurance a line and let them know you are running your own dishwasher firmware... I'm sure they will be interested!

Make sure you use a Watchdog timer and try and fail safe!

The whole point is that i can do a wash in 20 minutes or less while I am there rather than the current 23-3 hours which means I have to put it on a timer when I am not there. As for safety I am fast loosing confidence in everything. i recently found that my dehumidifier was intermittent due to a loose wire. I opened the plug up to find that one screw was not even screwed in and that the wire had just been sitting there making poor contact. But it's OK it has a CE mark and everything!

Yes i would do my best to make it as safe as possible. Things like over temperature protection can be done with an external comparator that can cut out the heater.

[Simon]

Writing your own dishwasher firmware is a little hairy, there is safety to think about with leaving a heater or fill solenoid on. You have to filter and debounce all inputs, and have timeouts if a switch or float gets stuck, pump doesn't work, that kind of thing. But nothing an Arduino couldn't pull off
The controller board looks straightforward, I would see if it's possible to read the dishwasher MCU's firmware and disassemble it.
Just need to post PC board pics and sketch a schematic to assign I/O, the MCU seems to have only 16 pins.

Thanks, that's very handy. Saves me a lot of reverse engineering.

[NivagSwerdna]

According to https://www.quora.com/What-OS-is-used-in-dishwashers there is an implication that at least one approach is FreeRTOS based... that would seem a good choice... perhaps something STM32 Nucleo or maybe a TI CC3200 LaunchPad might be a good choice of platform rather than squishing into an Arduino.
Sounds like a fun project.  You could start by logging the activity of the existing unit to get an idea for what it gets up to.
Update over the air or at least WiFi connectivity would stop you having to disassemble your kitchen all the time.
Have fun!

[Simon]

I just want to turn it into and industrial type. Fast and hot - no detergent required. I have used one before at a venue which is what prompted the purchase but this was a bit of a disappointment as it takes hours and does not always wash well.

[NivagSwerdna]

as it takes hours and does not always wash well.

I blame the EU.

[Simon]

as it takes hours and does not always wash well.

I blame the EU.

Don't be silly. I do not know why it has been done this way when other machines are faster and probably use less power. I'm sure that 20 minutes at 90C is less power than 2 hours at 60C. Maybe indesit did this to stop the machine being used professionally as it takes too long so that you have to buy a more expensive "professional" machine.

[NivagSwerdna]

Don't be silly.

Water consumption is a key criteria I believe. So sloshing less for longer...

https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=uriserv:OJ.L_.2019.315.01.0267.01.ENG&toc=OJ:L:2019:315:TOC

[Simon]

I would use the same amount. Long hot wash to get it all off, short hot wash to rinse it off.

[tunk]

Maybe it's cheaper to design it to run at 60C rather than 90C?
If that's the case, it may not last long if run at 90C, and you
may risk some of the plastics breaking and cause a leak.

[Simon]

Maybe it's cheaper to design it to run at 60C rather than 90C?
If that's the case, it may not last long if run at 90C, and you
may risk some of the plastics breaking and cause a leak.

I'm willing to take the risk. It goes to 70C tops, you would hope that in the name of safety everything is to withstand 100C. At 90C water is effectively boiling already so might have to be a bit less.

[tunk]

I don't have a clue about dishwashers, but there might be other
differences: higher pump/water pressure and faster heating in
the commercial versions.

Do you know what kind of temperature sensor it has? If it's an
NTC/PTC you may be able to fool it with a resistor in series or
parallel. It that works, run it for 20min and see if that cleans
your dishes. If so, put it on a timer for 20min.

[Simon]

Do you know what kind of temperature sensor it has? If it's an
NTC/PTC you may be able to fool it with a resistor in series or
parallel. It that works, run it for 20min and see if that cleans
your dishes. If so, put it on a timer for 20min.

That's a very good idea as t has a 30 minute light cycle at 40C, if I can make that 80-88C i will be happy for a start and see if it works.

[tunk]

Another thing you may bear in mind: Heatup time.
Looks like a dishwasher uses about 0.5-1kWh. If you assume all
is used for heating (not true) and have a 2kW element, heating
will take around 15-30 minutes (probably even more to reach
80-88C). Modifying the light cycle has a potential risk:
If you accidently put it in a higher temperature cycle, you
risk overheating/boiling.

Edit: It may have a mechanical thermostat as a safety to prevent
too high temperature. I suggest that you open the dishwasher to
find out what you have.

[madires]

I'd assume that you would have to spend a lot of time to experiment with timing, temperature and so on to get the best washing result.

[SilverSolder]

Professional dishwashing detergents often contain phosphates...   which is the real "secret" to making even ordinary household dishwashers perform well.

[Simon]

Another thing you may bear in mind: Heatup time.
Looks like a dishwasher uses about 0.5-1kWh. If you assume all
is used for heating (not true) and have a 2kW element, heating
will take around 15-30 minutes (probably even more to reach
80-88C). Modifying the light cycle has a potential risk:
If you accidently put it in a higher temperature cycle, you
risk overheating/boiling.

Edit: It may have a mechanical thermostat as a safety to prevent
too high temperature. I suggest that you open the dishwasher to
find out what you have.

No if you fool the thermistor it will simply read a different temperature. Once it gets to the new higher temperature it will stop. Only a few liters is used at a time so heating time should not be too long but this is the reason a completely new controller is actually probably safer.

[tunk]

I guess it depends on the sensor. If it's an NTC sensor and you fool it
to 85C in the 40C cycle, then it will never stop heating if you use the
70C cycle.

E.g. a 10k NTC:
40C 5.33k
70C 1.75k
85C 1.07k
I.e. to fool the 40C cycle you have to use a ~4.3k resistor in series.
In the 70C cycle you will then never reach 1.75k - it will never stop
heating (apart from the safety thermostat).

[Simon]

Yes true

[shakalnokturn]

Edit: It may have a mechanical thermostat as a safety to prevent
too high temperature. I suggest that you open the dishwasher to
find out what you have.

The service manual / power schematic shows there is one.

There may be a little time to spend on sniffing communications to the front panel off that is on a serial bus. Maybe not considering the number of pins on the interconnect.

[Simon]

There are unless i miscounted as many wires as there are buttons/switch positions/led,s on the front but I may have missed some so yes it could be that there is some comms but the control would all be in the main ECU i think.

Would the overflaw switch be what is used to tell if it is full? I see a flow meter but not sure if that is water in or circulation water to aid diagnostics.