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nRF52840 Bare Chip with Arduino Bootloader
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nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Fri May 17, 2019 12:43 pm

Hi all,

I've been using the nRF52840 Express with great success, and I noticed you also sell the nRF52840 separately. I am very comfortable with the Arduino environment, and I would be interested to know what it would take to program the nRF52840 board sold here using Arduino. I need a different power supply (either LTO or LiFePO4) for my project, and I am not quite ready to leap into native nRF programming.

Is it feasible or possible to program the nRF52840 with Arduino using the Adafruit libraries with the barebones chip? If so, could someone either explain how I would do that or point me to a tutorial?

Also, if anyone has any experience with LTO batteries and these microcontrollers, please feel free to provide input. They seem like a great fit for my application (my circuit uses 3mAh overall and around 40mA peak while powered -> I use the TPL to strobe power every 20m and I solar charge them in an outdoor application that sits outside 24/7). Thank you so much!

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Re: nRF52840 Bare Chip with Arduino Bootloader

by franklin97355 on Fri May 17, 2019 12:48 pm

As far as I know, it is not possible to use an Arduino to program the raw chip.

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Re: nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Fri May 17, 2019 12:54 pm

Even if I use an SWD and USB interface connected to it on a custom PCB? I'm basically trying to take the https://www.adafruit.com/product/4078 and possibly use Adafruit's bootloader to continue using Arduino. If I were to go with a different nRF52840 chip would it be the same process? I assume these chips are getting a bootloader somehow onto the chip, but I'm not sure if the Adafruit bootloader is very specific to the nRF sold here nor am I sure if it's even possible to do what I'm asking.

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Re: nRF52840 Bare Chip with Arduino Bootloader

by franklin97355 on Fri May 17, 2019 1:36 pm

You would need to follow the Nordic manuals and design your own process. We have no instructions for doing what you want, sorry.

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Re: nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Fri May 17, 2019 1:54 pm

Got it! So, just to post what I've learned... the Arduino platform is fantastic for prototyping and if you're ok with the power supply/consumption of the pre-flash/fabricated boards, then you can even use it beyond that.

Having said that, if you run into a scenario where you need some functionality (in my case, I am going to be powering my chip with an LTO battery, lower power consumption, and I need to lower costs) that is not easily provided on the board... you're looking at a custom board likely without Arduino (no bootloader needed).

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Re: nRF52840 Bare Chip with Arduino Bootloader

by danhalbert on Fri May 17, 2019 6:26 pm

The main issue is that the bare modules we sell have the Nordic bootloader installed, and you'll have to work with that. Reprogramming the bootloader requires accessing the device via the SWD pins. Once you install our bootloader, it will be usable from Arduino.

Instead of using the raw module, you might also look at the Nordic PCA10059, which is a nRF52840 on a tiny USB module. It's easier to get access to the pins.

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Re: nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Fri May 17, 2019 11:11 pm

That is excellent news! I've been using the nRF52840 Express, but I need an external antenna, LTO power supply (or LiFePO4), and the power consumption needs to go down (something on the board is drawing a lot of current). I would also be hooking up a different solar circuit.

So, if I were to get the same Raytac board (https://www.raytac.com/product/ins.php?index_id=79) and break out the SWD connector + USB interface, I should be able to upload the Adafruit bootloader onto the chip and use it just like an nRF52840 Express via the Arduino IDE? I've already written the code, so that would be incredible!

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Re: nRF52840 Bare Chip with Arduino Bootloader

by danhalbert on Sat May 18, 2019 7:55 am

Yes. All these use the same chip, either in or out of a module, so it's just the extra board circuitry that's drawing more current on the Feather. Other people also have nRF52840 boards that are mostly just a module, so you might see if you can spare yourself some hand assembly.

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Re: nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Sun May 19, 2019 12:05 pm

Thank you so much! I'll post my updates as I move along!

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Re: nRF52840 Bare Chip with Arduino Bootloader

by czuvich on Sat Jun 15, 2019 11:33 pm

Great news! I've been able to develop my own board and I've successfully uploaded the nRF52840 Adafruit bootloader! I am now able to power my own board via LiFePO4 and recharge via solar, AND use the powerful API and bootloader you guys have developed. I started off this project knowing nothing about hardware, and well a year later I'm that much closer to developing my own intelligent, remote relay management platform that should be able to operate off of 1 AA battery for years. I'll post a full thread at some point going over all of my experiences (once I actually complete this thing).

Thanks Adafruit!
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