cpu/nrf52/periph/i2c: 16-bit adressing

[nicoHarel]

Description

Hello everyone.
After my fix for cpp on the at24cx driver I tried using it in my app which is powered by a NRF52 MCU.

Big problem: the i2C periph of that MCU doesn't like it supports 16-bit register addressing (see: periph/i2c.c line 172)

Any reason why ?

Also a few lines later:

the nrf52's TWI device does not support to do two consecutive transfers
* without a repeated start condition in between. So we have to put all data
* to be transferred into a temporary buffer

That doesn't seem to be true:
See this link:
https://devzone.nordicsemi.com/f/nordic-q-a/5267/i2c-eeprom-with-16bit-addressing

I could use a use a 16KB AT24C chip but yeah... It's a bit small and ancient =)

Have a nice day.

[benpicco]

Any reason why?

My guess would be that nobody has gotten around to implementing it. If you want to take a stab at it, that would be great! 😃

[nicoHarel]

My guess would be that nobody has gotten around to implementing it. If you want to take a stab at it, that would be great! smiley

I'll have a look and give it a go as soon as I have a bit of time 😉

[nicoHarel]

Ok so a little update on this: - I won't open a PR just now because, unfortunately, I fail to see results with what I am trying to do. Write operation seems to be working (hard to confirm with my hardware and available tools at my disposal), but read operation is giving me nothing.

I did a bit of reading:

• The original PR: Driver for AT24CXXX EEPROM #11929
• The AT24C01/02/04/08/16 datasheet:
• The AT24C256C datasheet
• The NRF52 EasyDMA datasheet

Mostly I'm just posting this here so the links are there and to you guys updated. I'll of course open a PR as soon as I see results.

[nicoHarel]

Well obviously I just wrote this and now everything starts working.

Ignore the previous message 😆 I'll open a PR soon.