Is there no I2C/TWI peripheral example in the SDK documentation?

[la-ble]

As I run through the examples for the nRF51 S110 SDK, I'm not seeing anything for communicating with a sensor over I2C.

On a secondary note, since I have the option to talk to this sensor over SPI vs I2C, is SPI the recommended route to use for an nRF51822?

There are lots of tradeoffs between SPI and I2C in general. I'm just looking to understand tradeoffs between them in the context of an nRF51822. Is something unreliable with the TWI hardware peripheral? Will it will soon no longer be available? Will I generally get lower power consumption if I use SPI instead? Will there be less blocking code is I use SPI instead? etc.

[Stian Røed Hafskjold]

The TWI example was removed in SDK 7 after the introduction of the new development kit, because there was no TWI slave on the board that any TWI master examples could use.

You can of course use the TWI examples from SDK 6.1.0: developer.nordicsemi.com/.../a00051.html.

It might need some modifications to work with the TWI hardware driver in SDK 8: developer.nordicsemi.com/.../a00014.html

I guess the general tradeoffs are number of lines needed and speed. I believe the SPI would require less power because the execution time is lower, but I can not confirm that. The TWI hardware should be as reliable as the SPI hardware, and it will be available in the future.

[Bouke]

I can confirm that SPI is more energy efficient than TWI in general.

[Kevin]

I'm having a lot of trouble using TWI with the S110 softdevice and v8.0 sdk. Specifically, the softdevice cannot find nrf_delay.h. The workaround has been to not include the twi while compiling the softdevice, then include it when compiling application code. I understand there isn't a need for TWI in the sdk examples since not TWI slave is on the new board, but, it seems like the consequence is inadvertently dropping TWI support entirely...

[Stian Røed Hafskjold]

I agree that it should definitely be a TWI example in the SDK. However, there is a TWI driver in the SDK8.0 (and a completely new and improved driver in SDK8.1), which has twi_master_init and twi_master_transfer functions, so I wouldn't say that the TWI support is dropped entirely.

[Kevin]

Thanks for pointing out that there is a new driver in 8.1, @Stian. I'll try it out today, and hopefully it will resolve my nrf_delay problem :)