MMA845x (GY-45) and NRF52-DK with I2C/TWI: HELP

RE: MMA845x (GY-45) and NRF52-DK with I2C/TWI: HELP

Jørgen Holmefjord — Fri, 25 May 2018 09:08:45 GMT

Have you connected the GY-45 Module directly to an unmodified nRF52-DK/PCA10040 board?

If you use the TWI driver in the SDK (used by TWI scanner example), the pullups will be enabled. If they are enabled in mbed depends on what version and API you are using. Most likely they are enabled, but to be sure, you need to follow the API back to the implementation in the GitHub repository I linked in my last post.

RE: MMA845x (GY-45) and NRF52-DK with I2C/TWI: HELP

aldrinleal — Wed, 23 May 2018 18:29:47 GMT

Hi Jørgen,

I tried both on mbed as well as TWI_Scanner as well (NRF5 sdk version 12.3). On both cases, they report all addresses as available (which is a sign that its not working)

Question: Will both mbed and NRF5-sdk will enable the internal pullup?

RE: MMA845x (GY-45) and NRF52-DK with I2C/TWI: HELP

Jørgen Holmefjord — Wed, 23 May 2018 18:21:56 GMT

Hi,

Can you provide a more detailed description of what is not working than "Somehow, its not working"? Did you test the TWI scanner example from our SDK?

You have not included any information on what mbed version your are using, or how you configure TWI/I2C in your code. mbed include the TWI driver from our SDK, and use this for some of the I2C code. This driver will enable internal pullup resistor for both SCL and SDA, maybe this could explain the value you are seeing? The pullups should be between 11 and 16 kohm, with a typical value of 13k.