Replicate "Mi Band" wristband functionnalities, hardware ?

[jerome]

Hi,

Same question in the ARM forum: topic

I am a (French, sorry for my English) software engineer with very little knowledge in hardware. As part of a prototype, I'd like to replicate the functionalities of " Mi Band" wristband.

First , I would like to control the lighting of a LED and retrieve the motion sensor data through bluetooth .

Secondly , I would like to control a capacity touch sensor and vibrator sensor.

Now, I need your help to choose the Hardware !

Based on my research, the NRF51-DK board seems ideal. It is "mbed enabled" based on the Low-Power Cortex M0 chip, already has a LED and a button

What about the others sensors. I have take a look at developer.mbed.org/.../ but i'm lost. Ideally , I'd like to find examples to speed up my prototyping and sensors that are plug and play (ideally of course :D) with the board.

Motion sensor:

• ADXL362 (3-axis) -> developer.mbed.org/.../

• MPU-9150 (9 -axis) -> developer.mbed.org/.../, project based on http://www.twiz.io/

• BNO055 (9-axis) -> developer.mbed.org/.../ - ...

Vibration sensor ?

Capacity sensor ?

Please help me :D ! Thanks.

[Susheel Nuguru]

There are very few plug and play drivers that we give with our software, most of them are legacy. There is a lot of discussion here on this on devzone on many sensors, but we here at Nordic are not testing or recommending anything.

Motion: ADXL362 is well discussed and implemented. Capacity sensor: www.sparkfun.com/.../9695 this is well documented and there are tutorials on the page. vibration sensor: www.sparkfun.com/.../9196

I am not recommending anything, because we at Nordic should work with any sensor with standard interface. I am just posting you my findings :)

[jerome]

What about the NRF52 ? This board is the successor of the NRF51.

I'm wondering if the difference of power consumption is "huge", in the wearable context, between Cortex M0 and M4F.

[Susheel Nuguru]

NRF52 is better choice with respect to power consumption and execution power because of the M4F running at 32MHz. The peripherals in NRF52 have more options with more modules having EasyDMA in them. But it is worth mentioning that NRF52 is in its beta phase but it is well suited for development.