Extending Blinky to talk to i2c breakout board

Question

Hello, I'm playing around with the Moto Mods developer resources and have gotten the 'blinky' examples working. Embedded development is a bit new to me, so this has been a lot to learn at once! My apologies in advance if this question is inappropriate for here.

I want to extend the "Blinky" example so that the toggle switch in the Android app causes a simple change in an i2c IC that I'm adding to the perfboard. Do I need to create an entire "device driver" for my IC (the TI DRV2667)? (If so, can anyone point me to a guide through that process?) Or can I just extend "stm32_modsraw_blinky.c" to use the i2c methods at "<nuttx/i2c.h>" like other examples do?

...as you might have gathered, I'm coming from the world of Arduino, so both embedded linux and the particular microcontroller here are both new to me. I am a determined learner, though, so any help or links would be much appreciated!

AKA

motomodsdev · Answer

Take a look at the nuttx Porting Guide , that should have some advice. You're on the right track, but you'll need to actually write an i2c driver. You don't need to implement all the functionality, but you can limit it to just what you plan on using. You'll need to configure the appropriate MuC pins as i2c, make sure addressing is correct, etc, you'll do this in menuconfig (both under STM32 Peripherals and under Device Drivers). In the MDK, you can look at the BQ driver, or the MAX17050 fuel gauge. Both of those connect to the MuC via i2c and can be found in nuttx/nuttx/drivers/power.