Hi guys, I am a software engineer and I am working on a new wearable prototype (wristband kind).
At the moment I used an Arduino Uno starting kit to start to configure my Android and iOS SDK just to make some proof of concepts.
Right now I am in the phase of choosing the first development board for my physical prototype. The idea is to work on ARM Cortex A for low energy comsumption but also ARM Cortex M is interesting even if I believe that its power will blow away the battery in few days.
Before desigining any custom PCB I want to test out an ARM Cortex, plug my sensors, write the internal OS of the wearable and more forward from there.
What development kit do you suggest me to start with the evaluation of the ARM Cortex MicroCrontroller and mbed OS system?I have few requirements to start with:
About the sensors I don't really need a development board with already a gyro or other sensors in it. But I want the possibility of tests my own sensors with mbed OS.
It would be nice if you can point me to some development board kits like the Arduino Uno. Then from there my plan is to slowly design various versions of my custom PCB as soon as I have a stable prototype done with the development board.
May I suggest the nRF51822 mkit from Nordic Semiconductor? I've used this board a few times now and it's consistently dependable. I did a review of it a few months ago Out of Box Analysis: Nordic nRF51822-mKIT ***PRIZE POST*** and it seems to fit the parameters you have mentioned here. It's mbed compatible, has 2 LEDs, 2 push buttons, and pinouts for sensor testing, runs BLE, runs on a Cortex-M3 processor and has Flash and RAM memory. It's relatively small for prototyping and the nrf51822 SoC will take very little space on a custom PCB. It can also be powered by a single 2032 coin-cell battery with an on-board battery holder, USB, or a different external power source.
Is this the type of board you are looking for or am I missing a crucial likeness to the Arduino Uno?
Hi Carissa and thank you for your answer. I had a look at the product description. Actually the board seems nice I just had a look at the presentation PDF for the version nRF51822-mKIT.
Unfortunately the board seems to be dismissed cause on DigiKey the price is not available and there is no availability in stock. The price is a bit high, is about 60 Euro which is quite expensive for a development kit.
Can be a little hassle the way the analog and digital inputs are provided, they have pin header so it requires some extra work.
Nordic suggests to move away from that model and try the new nRF51 DK kit available here: nRF51 DK - Nordic Semiconductor
I think I will give a shot to this version but again, we are talking about 75$ for this version which includes only the board without a screen. But it seems to be the way to go for embed prototyping. Also the size is interesting.
If I start with this board, any OLED screen and any sensor can be connected or do I have some limitations?
please check out
once you pick your platform, you can then add the connectivity, sensor and display modules you need.
you have different models at varying price points
Thank you Diya for the reply.
Actually is my fault, I didn't notice that area of the web site. Interesting cause I found some PCB to be quite inexpensive and I can even start to program an M0 and move forward if I realize I need more CPU power.
I think I can choose from those:
But if I look in terms of Price/Flexibility this one Nordic nRF51-DK seems to be best choice to start with.
It would be very interesting, if you have the time, to write a blog on your progress with this project.
What you are doing involves pulling together HW, SW, Sensors, Connectivity, etc etc to create a prototype.
I believe many people would love to know the good things and the bad things that you will encounter in building your prototype.
I have a technical blog here: Raffaeu's blog | A NET coder relocated in TurkeyAs soon as I will have something working and I will start to write firmwares in mbed OS and SDK for Android for sure I'll write some posts.
The nRF51 DK also looks like an excellent option- for the cost of a little more real estate you get twice the buttons and LEDs plus the compatibility to Arduino R3 shields. If you are looking for something cheaper there is also the RedBearLab board RedBearLab nRF51822 | mbed which uses the same SoC but you will also lose the nice on-board peripherals for testing that you will have to purchase later. Finally you could get something like the $10 Nucleo board and purchase a BLE shield (Seeed Bluetooth Shield | mbed). It comes down to a trade off of either cleaner prototyping for a higher price or half the price but the prototype will be more piece-meal.
As for the OLED screen, have you taken a look at the mbed-ready options? Components | mbed These mean the library is already in place to start communicating with the board. I need to look into it more but I'm not seeing 5V compatible pins so that may be a limitation. Let me dig some more into that and get back to you on that piece =).
Carissa thank you so much for your precious answers. I didn't see the available display drivers but at the end I browsed also SparkFun and it seems that the best deal so far is this one:
mbed Application Board
Then I can easily choose external sensors and develop my prototype code and hardware. It's about 59$ including screen, gyro, battery support and more.
I think I will probably follow this path. Use this board and buy the final sensors. Develop the entire firmware and when the prototype is stable enoughI will design my own PCB and try to shrink all those components into a flexible PCB.
So after some researches I came up with a first development kit board. You guys have also to consider that now I am based in Turkey and only some distributors can reach me here without the burdain of paying tons of import taxes.
Below is my BOM and the motivation
Development board (one of them)
For sure the Sensors and the Bluetooth will require custom firmware for mbed OS but at the end I will have a custom solution.
That's my resource update so far
So, as a final choice I will start with the following components:
I will start by writing the SDK for Android and iOS and the PCB menu class. Will post some updates as soon as the hardware is delivered and I have a working sample.Note: On Nordic web site they suggest to start with the nRF51-DK because the other boards will be discontinued soon so this is why I didn't choose the famous LPC1768
Please can anyone help me,,I have a testbed for mbed board and lpc1768 MCu.
I want to connect it to bluetooth and use piezo speaker?