Write protect on the EPROM

[chiisai-fukurou]

Hi, I’ve looked at the documentation of the EPROM and saw that it has a write protect pin.

Did you try out connecting the WP pin to Vcc?

I want to try and connect the detergent tanks directly to the internal dosage pumps of bob to avoid having to refill the cassettes. I’d still need the EPROM of the Cassette to get it to work tho. So my train of thought is that Bob couldn’t modify the value on the EPROM anymore, reading the same number of cycles every time.

Also sorry if im getting things wrong… it’s been quite a few years since I worked on anything electronic :|

Thanks anyways :)

[dekuNukem]

Here's the description of the write protect (WP) pin:

and here is how it is wired up on the circuit board:

You can see that it is connected to the ground plane UNDER the chip, which disables the write protect, allowing the EEPROM to be written to.

If you want to enable the WP again, you would need to either:

• Bend the pin upwards so it's not touching the pad, or...
• Desolder the chip, cut the connection to the ground plane, solder it back on

Then, you can connect that pin to VCC, which should then enable the write protect.

I haven't tried it myself, but it would be interesting to see what happens.

[dekuNukem]

Good news! I have tested out the Write Protect, and it works! The wash count will be frozen, and Bob still works.

I have written a guide, check it out here:

https://github.com/dekuNukem/bob_cassette_rewinder/blob/master/user_manual.md#can-i-enable-write-protect-wp-to-lock-out-wash-count

[bendardenne]

Good news! I have tested out the Write Protect, and it works! The wash count will be frozen, and Bob still works.

I have written a guide, check it out here:

https://github.com/dekuNukem/bob_cassette_rewinder/blob/master/user_manual.md#can-i-enable-write-protect-wp-to-lock-out-wash-count

Excellent news! I will try this with my current cassette once it runs out.

Couldn't they update the software to refuse the cassette if the eeprom cannot be written? I would probably disable over-the-air updates if I used this approach, what do you think?

[dekuNukem]

It's definitely a good idea to keep it offline. There'ss no reason for a dishwasher to be online anyway, especially now it can be refilled! 😅