Resetting Write Protect (WP) bit on MCP46XX digital potentiometer

[fedeza]

Hi all,

I'm a noob here, so apologies if my question may seem a bit simple.

I am using a MCP4661 10K digital potentiometer (Microchip, datasheet found here: https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/22096b.pdf) and I'm interested in writing a value into the non-volatile register for wiper 0 or wiper 1. On my PCB, the WP* pin on the IC (active low) is connected to a GPIO of my MCU and set high (3.3V), whereas pins A0, A1, A2 are tied to ground (connected to ground plane using vias underneath pads) to assign the slave address for I2C (I am using 2 units of this digipot on the same I2C bus).

My question is: how can I reset the internal WP bit so that I can write to the memory, please? I read the datasheet over and over again but I am just more confused. Should I put a high voltage (8.5V-12.5V) on the WP* pin or on the A0 pin before I send the I2C command to reset the WP bit? Or should I do something else? I just can't figure it out.

Any suggestion is very much appreciated, please!

[DavidAlfa]

Basically, yes. Also read 22107B, page 20

[fedeza]

Hi DavidAlfa,

Thanks for your help. I had a look at the datasheet you linked and that is in fact the one I meant to include the link for since I'm using the Nonvolatile Memory MCP4661, so apologies for that. I'm not too sure which section of page 20 you're suggesting I should look at. Could you specify which graph, please?

Regarding my issue her:

1. The WP* physical pin tied to 3.3V is effectively useless and is not sufficient to reset the WP bit?
2. If I were to connect the WP* to my 12V supply, would that be enough to be able to write to the memory? Or would I still need to put high voltage onto A0 and send the below command to register 0x0F to achieve that? Or both simultaneously maybe?


Thanks again!