I2C/TWI slave with nRF51822

RE: I2C/TWI slave with nRF51822

ti_me1 — Fri, 19 Sep 2014 12:33:06 GMT

In our application, the nRF51 needs to combine the role as I2C-slave and I2C-master at the same bus. This is because we have event triggered I2C-telegrams in both directions. As long as the nRF51 does not have any telegram to send, it listenes in slave mode. If it wants to send a telegramm, it switches temporarily to master mode.

Afaik, the SC18IS602B works only as I2C-slave. At the moment, I am thinking about using the nRF51 peripheral TWI0 as I2C-master and the SPI0 to connect the SC18IS602B. The I2C-bus of this chip I want to connect to the TWI0. If anyone knows a simpler solution, I would be very interested.

@Adrian: For me, too, I2C-slave functionality is a point for the wishlist of the next chip generation from Nordic.

RE: I2C/TWI slave with nRF51822

Adrian Eggenberger — Thu, 08 May 2014 06:11:34 GMT

It apears that the bridge chip is the only real way to do. The software I2C can't be done with a parallel working softdevice. I agree it would be better to have an integrated way to do. Maybe a point for the wishlist for the next gen chip from Nordic?

RE: I2C/TWI slave with nRF51822

Jarmo — Fri, 28 Feb 2014 14:52:05 GMT

Yesterday I set up nRF51822 Evaluation Board to become I2C-master and to connect to some I2C-devices, and it seems to work. I just needed four wires from the board's pins to connect to I2C devices (GND, Vcc, SCL and SDA). The code I used was from Nordic's example, twi_hw_master.c or something like that.

However, we would also need to have I2C-slave there because the system connects to another system as a slave while being master for the another part. I am thinking if SPI-slave could somehow be tricked to become I2C-slave, or would there be any efficient way to do it in software (interrupts?).

The bridge chip I mentioned is one possible solution, but not an optimal one.

RE: I2C/TWI slave with nRF51822

ABDELLI-W — Thu, 27 Feb 2014 09:42:51 GMT

Hi, I'm in the same context, i want to create an I2C library. Please, help me to prepare this project and how i add the includes for so that the compilation works well Thanks

RE: I2C/TWI slave with nRF51822

Adrian Eggenberger — Wed, 26 Feb 2014 13:16:49 GMT

Thank you for this answer. I guess this will work with the nRF51822. I'll have a closer look to the NXP chip.

RE: I2C/TWI slave with nRF51822

Jarmo — Wed, 26 Feb 2014 12:23:20 GMT

We have used a chip of type "SC18IS602B I2C-bus to SPI bridge" that seems to work, although we used it with an atmel atmega32u4. But there's no reason it wouldn't work with nRF51822, too. However, it's not very simple to use in case you want to read data from the slave. Doable, but requires a bit patience to get everything working.

Regards,

Jarmo Nikula iProtoXi Oy