nRF5 action!

monte

I can do a diff later this evening if you're interested...?

Yes please, I think I'm not the only one who will appreciate your code :)
I have a bunch of 51822's but wanted to get into 52840. I have paused my research of NRF5 for some time, while I am finishing my other work, but I would like to have more complete experience with NRF5 than what is now provided by mysensors.
I guess FreeRTOS is a way to go, when you have far mo complex MCU then atmega, and far more capable.
I hope that mysensors core team will consider moving forward to more complex, but more powerful architecture.

acb

@monte: Okay, sorry for the delay in getting back to you about this (- FWIW: UK went into another national lockdown, schools closed, so it’s been pretty crazy here the last few days...!)

I’ve dug back into my original code, done some experimenting and have tried to get down to a minimal set of steps necessary to get MySensors code to play "nicely" with a SoftDevice. Hopefully it’ll be helpful as a starting point. But note that minimal is not optimal - or even the best - see more on that below.

Caveats aside...

As far as prepping the nRF52832 goes, this HEX file will load the chip with the following MySensors-compatible regions either “in-mind” or in-place:

0x00000 to 0x00FFF -   4K MBR Region, currently up to 0xAFF.
0x01000 to 0x25FFF - 148K SoftDevice Region, currently with S132 up to 0x2514F.
0x26000 to 0x6FFFF - 272K Application Region, bootloader intelligently fills.
0x70000 to 0x70FFF -   4K VirtualPage? managed by arduino-NVM.
0x74000 to 0x7EFFF -  44K Bootloader Region, currently custom up to 0x78FCB.
0x7F000 to 0x7FFFF -   4K “EEPROM” Area? managed by arduino-NVM.

It’s best to get the bootloader to load the application code (via an FTDI) since it knows where to put it, otherwise you’re doing it manually with a JLink, etc.

The linked bootloader also expects:

UART TX on P0.11
UART RX on P0.12
USR BTN on P0.15
BLE DFU on P0.16
MCU RST on P0.21

Other optional, but useful pins are:

LED1 on P0.13
LED2 on P0.08

Once the above-linked HEX has been flashed (using JLink, BMP, etc.), you can boot the nRF52832 into a state where it is expecting a DFU over UART by grounding USR BTN (P0.15) and resetting (ground P0.21 briefly). LED1 will fade up and down slowly to confirm the new state.

Or you could do this over BLE by grounding both USR BTN and BLE DFU (P0.16) and resetting. LED1 and LED2 will fade up and down more quickly to confirm.

I’ve found the custom tools in Adafruit’s nRF52 BSP for Arduino to be pretty solid for FTDI uploading, but YMMV. Otherwise, it’s Nordic’s nRF Toolbox app.

(Note that if you do go with Adafruit’s BSP, you can call built-in functions in your Sketch code like enterSerialDfu() and enterOTADfu() to perform the same button operations as above.)

As far as prepping MySensors goes, these are (I think) the minimum files and modifications needed to make things work. In summary:

Either comment out the define check for NRF5 right at the bottom of MySensors/drivers/NVM/Flash.h (or define it somewhere) so that the flash driver gets compiled. This is the only file that uses that define, AFAIK.
If you’re using Adafruit’s nRF52 BSP (recommended), you have to make sure MySensors uses the correct pin assignment array. Quick hack is to just replace line 37 of nrf5_wiring_digital.c (MySensors/hal/architecture/NRF5/drivers) with ulPin = g_ADigitalPinMap[ulPin];
Finally, you will probably want to play around with the implementation of MySensors and FreeRTOS in this MyMainNRF5.cpp file (replacing the one in MySensors/hal/architecture/NRF5).

This last file is where FreeRTOS is being used to create a sort of Arduino-like structure with a loop_task() being added to the scheduler that contains both the usual setup() and loop() functions you’ll probably be familiar with from Arduino IDE land - setup() is run by MySensors inside the _begin() function.

Note that this is NOT the best or lowest power way to do this! But it is (possibly) the fastest way to get your existing MySensors sketches up and running.

Remember that this is now an RTOS running on the MCU. So ideally, you probably want to completely dispense with system ticks and move to a setup that only uses interrupts, timers, callbacks, etc. to get the lowest possible power, depending on what you’re trying to do in your Sketch. If you want a quick-and-dirty low power hack, just lower the configTICK_RATE_HZ define in FreeRTOSConfig.h (Adafruit nRF52 BSP) to something like 4 (Hz) or so - but that not the “right” way to do it...

However, that’s outside the scope of this (now, not-so) little post. If you want to dig deeper, I’d suggest familiarising yourself with FreeRTOS and reading through this low power Github issue with Adafruit’s implementation and the associated links mentioned in it - this page from FreeRTOS on Low Power Tickless Idle Support is good too. Here’s an example of an Arduino Sketch using tasks, timers and interrupts - but using Bluetooth - that illustrates a loop-less implementation.

I’ve tinkered down to the 2 or 3 µA region with MySensors using the RTC, portsense interrupts, etc. and you can, of course, go sub-µA using a custom SYSTEM OFF sleep implementation and an external nA region RTC.

I can try to put together a better MySensors integration, if folk are interested. It’ll take time though, especially now that we’re locked down for the next month…

Anyway, hope that was helpful. Any questions, I’ll do my best to respond with what I know.

(P.S. Oh, and you'll need the latest MySensors development branch to get the most stable nRF52832 radio implementation.)

Have fun! :)

monte

@acb thank you for such complete answer!
One more question for now, is this standard, or modified bootloader?
And how many additional steps do I need to take to make this work on nrf52840?

acb

@monte - Glad you found it helpful!

The bootloader I linked to is a custom (modified) one to fit the board I'm using. I remember tinkering with things like buffer sizes to make large BLE DFUs more reliable - I'd have to dig back into my notes to be sure...

But I believe Adafruit's standard nRF52 Feather should keep approximately the same memory regions - which is the "main" hurdle. I think the only other potential issue for the nRF52832 was their use of a BOOTLOADER_SETTINGS region at 0x7F000, so you'll have to check that it's not in the way of the arduino-NVM sections. On the Adafruit Bootloader side, it's all linker-related, nrf52.ld is the file I think.

Or you can, of course, modify arduino-NVM to pick it's sections somewhere else, say, underneath the bootloader, for example. Just be sure to limit how much it erases from there.

I remember nRF52840 being trickier because Adafruit had (and used) both the BOOTLOADER_SETTINGS region (this time at 0xFF000) and a BOOTLOADER_CONFIG region (at 0xFE000 - 2K, or something like that...) which they used for USB VID+PID, UF2 family, etc.

I've got a similar (custom) Adafruit-based bootloader I made for Nordic's nRF52840 Dongle that works with MySensors, if you're interested?

I couldn't get Nordic's default Dongle bootloader to play nicely with MySensors (at the time). They sign their bootloader so you can't replace it through nRF Connect without a JLink/BMP/etc. - you have to wipe the chip completely - which creates another problem. The bootloader also needs to set REGOUT0 in the UICR to 3v so you can see your LEDs and debug the thing without level-shifting (the default is 1.8v). Anyway, it does all work (eventually!) - I've currently got a Dongle serial gateway and Dongle nodes running in various places. Oh, you'll need to up the data rate too, since the 840 doesn't support the MySensors (deprecated) default of 250kbps.

Does that help at all?

What nRF52840 board(s) do you have?

monte

@acb I have a couple of Ebyte's E73 modules. I also have BMP, so it shouldn't be a problem.
If you could share your bootloader for 52840 it would be a great start for my tinkering.

@acb said in nRF5 action!:

I couldn't get Nordic's default Dongle bootloader to play nicely with MySensors (at the time).

So have you gotten any success eventually?
Once again, thank you for such extensive information :) I hope others will appreciate it too.

NeverDie

@monte said in nRF5 action!:

I hope others will appreciate it too.

Yes! Any examples which shed light on how to write a custom bootloader for the nRF52 would be greatly appreciated.

orhanyor

I just gave this design to pcb fab and cant wait to test it out. I made and tested a similar board using nrf52840 but soldering aQFN package is a nightmare and i needed to cancel quite abit of pins to increase the success chance.
So this design is based on nrf52832with a normal QFN package which is easy to solder and that allowed me to breakout every single pin (except P0.07). Can be powered with a single cell lipo or USB port and managed to fit in a charger for it with a charging indicator led. It has a voltage divider to measure the battery but it can be desoldered if the pin is needed for another function.
Comes with PA and LNA just like my nrf52840 test and had to follow quite abit of design recommendations from the datasheet.
Some pins are compatible with adafruit 52832 circuit design just in case if i want to use their bootloader. Like reset, DFU, 2 different leds are connected to the same pins as in their board design. Also theres a selector 0 ohm resistor between pcb and external antenna.
I will report when i receive and test it!

acb

@monte, @NeverDie - Took some time this weekend to take a look at this and used my previous post as something of a template; hope it helps...

Re: Nordic’s default Dongle bootloader - I never managed to get it to play nicely with MySensors and so abandoned it completely in favor of a modified version of Adafruit’s again, since I was already familiar with it from my nRF52832 work. It would have been nice if Nordic had revealed their private key to move/replace their bootloader, but I get it, I figure they’d rather you bought their DK.

This is the custom bootloader (.HEX file) my Nordic nRF52840 Dongle nodes currently use. You’ll need to completely wipe any current Dongle (or EByte E73 module) using a JLink/BMP before flashing. It has the following MySensors-compatible regions either “in-mind” or in-place:

0x00000 to 0x00FFF - 4K MBR Region, currently up to 0xAFF.
0x01000 to 0x25FFF - 148K SoftDevice Region, currently with S140 up to 0x25DE7.
0x26000 to 0xEFFFF - 807K Application Region, bootloader will intelligently fill.
0xF0000 to 0xF0FFF - 4K VirtualPage? managed by arduino-NVM.
0xF4000 to 0xFD7FF - 38K Bootloader Region, currently custom up to 0xFC01F.
0xFD800 to 0xFDFFF - 2K Bootloader Config, currently custom up to 0xFD857, 88B.
0xFF000 to 0xFFFFF - 4K “EEPROM” Area? managed by arduino-NVM.

The linked bootloader will of course expect the same pin connections as the Dongle. The important ones are probably only:

LED1_YLW_GREEN on P0.06

LED2_RGB_RED   on P0.08
LED2_RGB_GREEN on P1.09
LED2_RGB_BLUE  on P0.12

USR BTN on P1.06
BLE DFU on P1.10

MCU RST on P0.21

The bootloader supports CDC, DFU and UF2 upload modes. So the first time you flash the bootloader and reset, you can then mount it as a removable drive with UF2 support for drag-and-drop uploading of applications and/or new bootloader images, etc.

It should also appear as a usual COM port via it’s CDC descriptors, enabling FTDI-like uploading through PlatformIO/Arduino IDEs. And as before, you can perform DFUs over BLE through a manual combination button-press - more on that below...

Also as before, the bootloader shows the upload state through the LEDs, but note that on the Dongle, the LEDs are all active LOW - i.e. drive a logic zero (‘0’) to illuminate the LED(s). If you’d like a version of the bootloader where the LEDs are all active HIGH, let me know and I’ll try to dig out my old environment and compile something - you can do this yourself though… ;)

Manually entering these upload states is similar to the nRF52832. Uploading via FTDI works as you would expect. Ground P1.06 (USR BTN) and reset (ground P0.21, MCU RST, briefly) and the nRF52840 will expect a DFU over USB either via it’s COM port or UF2 if mounted. On the Dongle, LED1 will fade up and down slowly and I think the RGB LED goes green if mounted.

For DFUs over BLE, ground P1.06 (USR BTN) and P1.10 and reset. I chose P1.10 because it’s right next to a ground pin on the Dongle and I just soldered another push switch to it. LED1 fades up and down more quickly together with the RGB LED turning blue to confirm. Uploading is via Nordic’s nRF Toolbox app and again, if you’re using Adafruit’s BSP you’ll get the built-in enterSerialDfu() and enterOTADfu() sketch functions to perform the same button operations as above.

As far as prepping MySensors goes, the same applies as above with the nRF52832, only this time you’ll need to up the data rate to 1Mbps or higher, as I mentioned earlier.

I could upload Arduino IDE and PlatformIO board variants for the Dongle if you’d like. But it’s straightforward enough to create variants for your specific board. If you’re using the Dongle, probably the most useful thing I have to hand is this code-snippet for enabling the regulator:

// Set REGOUT0 to 3V mode
// https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial
if ((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) ==
    (UICR_REGOUT0_VOUT_DEFAULT << UICR_REGOUT0_VOUT_Pos))
{
    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy);

    NRF_UICR->REGOUT0 = (NRF_UICR->REGOUT0 & ~((uint32_t)UICR_REGOUT0_VOUT_Msk)) |
                        (UICR_REGOUT0_VOUT_3V0 << UICR_REGOUT0_VOUT_Pos);

    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy);

    // System reset is needed to update UICR registers.
    NVIC_SystemReset();
}

If you stick this in an initVariant function in your variants.cpp, the Adafruit nRF52 BSP will call it as part of main.

I think that's everything - I hope it was helpful - any questions, I’ll do my best to respond a bit faster this time!

Famous last words... ;)

NeverDie

@acb Thanks for your post!

My nRF52 skills have gotten a bit rusty, so in case you're no longer around when I circle back to this toopic in the future, I'm going to jump the gun and ask you now so that your answer can be memorialized here and then suitably curated by Hek for years to come: How exactly do you ensure that your bootloader is loaded into the proper bootloader memory segments and not treated like a regular program and stored in ordinary, non-privlidged program memory? I'm guessing it's accomplished through a linker directive of some kind? If you could share even a brief simple example here on how to implant the bootloader code where it needs to be, I'm sure it would be immensely helpful to anyone who wants to create a custom bootloader of their own. ;-)

Actually, it seems you did offer a summary of how to do it when you wrote "Manually entering these upload states is similar to the nRF52832. Uploading via FTDI works as you would expect. Ground P1.06 (USR BTN) and reset (ground P0.21, MCU RST, briefly) and the nRF52840 will expect a DFU over USB either via it’s COM port or UF2 if mounted. On the Dongle, LED1 will fade up and down slowly and I think the RGB LED goes green if mounted.", but again a step-by-step actual example, with demo files, would really drive it home. Now, some people might consider that much detail would constitute a "no thinking required" guide and therefore overkill, but I'd prefer overkill to underkill any day. I'm sure at least some others who are reading this would rather have s complete demo example that's too basic than have to puzzle over a missing or vague step. It may not seem like it's missing or vague to you now, but believe me if you ever have to switch to a different project for a while, it might not look anywhere near as obvious or as familiar when you come back to pick up where you left off.

So, if I can prevail upon you to put together even a very simple demo, I'd volunteer right away as a test subject to see if I could replicate it. And if I can, then you can be confident that if you had to shelf your work then you could come back years later and resume without help just based upon re-reading your own notes. :sunglasses:

acb

Thanks @NeverDie, I appreciate that.

Okay, well, the short answer to your question is yes, it’s a “linker directive” or rather a series of them, usually a file with the .ld extension. There’s normally a general stack/heap/etc. one called nrf_common.ld in Adafruit’s BSP, and then an architecture-specific one: nrf52.ld I think for the nRF52832 and nrf52840.ld for, well, I bet you can guess! ;)

This architecture-specific linker directive contains the memory locations for things like the MBR, ram region for the bootloader, initialized and (shared) non-init RAM, bootloader settings/configuration, MBR parameters, etc. The bootloader itself can of course read this memory allocation/settings/configuration data and then load any new application code or indeed new bootloader code wherever it needs to be. That’s why it’s best to let the bootloader perform the FOTA, either via serial or BLE.

Now I’m guessing here, but ideally, the arduino-NVM library that sort of emulates AVR EEPROM for MySensors could just read this information too and store it’s virtual EEPROM pages around these allocations. Currently, I think it just tries to determine the top application page address from the UICR and then allocate the pages based on that. It’s been a while since I looked at the code, so it might have changed. Essentially, it’s trying to find where the bootloader starts (if there is one) and allocate some pages a bit back from there to be safe.

In theory, a large enough application could overwrite this area - that’s why it’s not the best solution as I mentioned earlier - but if you reach that point, you’ve gotten so close to the bootloader with your application code, you might be in (other) trouble anyway! ;)

As far as a step-by-step with actual example code, demo files, etc. I’m more than happy to do it but it’ll take me some time. And would be helped if you could specify a particular board you’d like me to target (especially if I have one lying around), e.g. Nordic’s nRF52840 Dongle, Ebyte module, etc?

The other side of this is the FreeRTOS side. Would you like examples for the lowest possible power?

It seems like that’s how folk like these devices to operate. Going down around 2µA in bare System ON sleep (nRF52832) and around 300nA in bare System OFF sleep requires more involved MySensors code modifications, due to (among other things!) how FreeRTOS takes care of the power management when idling, use of the RTC(s), how it handles ISR callbacks, attaches interrupts, etc. By “bare” I mean no additional sensors, just, for example, a button or internal RTC (only in System ON) to wake it.

Does all, or at least some, of that make sense? :)

NeverDie

@acb said in nRF5 action!:

As far as a step-by-step with actual example code, demo files, etc. I’m more than happy to do it but it’ll take me some time. And would be helped if you could specify a particular board you’d like me to target (especially if I have one lying around), e.g. Nordic’s nRF52840 Dongle, Ebyte module, etc?

Yes to nRF52840. Dealer's choice as to which nRF52840 module--i.e. I'm neutral, so whatever is more convenient for you. I suppose for others reading this the dongle might be a good choice though.

The other side of this is the FreeRTOS side. Would you like examples for the lowest possible power?

Is FreeRTOS definitely required? I suppose I could live with it, but as a simple demo even just some simple code that did nothing more than blink an LED and which resided where the bootloader out to be and which got loaded automatically from protected memory on reset as though it were a real bootloader is sufficient. If I knew how to do that one small thing, then I presume I could extend it to be a real wireless bootloader instead of just an LED blinker. I'm just missing the info on how to put code into the privileged and normally protected bootloader location. I'm hoping it's actually pretty simple and straightforward and not something lengthy and complex like the way the Nordic SDK advocates doing it.

Jon Raymond

@ncollins Hey any update on your NRF52805 Breakout work? I've got a couple of the Ebyte modules that I have been playing around with. Found your pull request on GitHub for board support in sandeepmistry's nrf5 core. Wondering if you got any further as the pull request hasn't been merged and it would be great to see Arduino support for these modules.

ncollins

@Jon-Raymond I kinda got hung up on the last conversation in the merge request and haven't looked at it since. Let me push the changes I have to address the other comments, then try to figure out how to best handle that last bit.

Jon Raymond

@ncollins That's great, thanks!

ncollins

@Jon-Raymond I pushed my latest changes, posted a question to the merge about next steps.

Jon Raymond

@ncollins Here is my version of a breakout for the nRF52805.

Been playing around with your fork/pull request and I do have one question.

Should there be a SoftDevice for this? According to Nordic it needs either S112 or S113 for BLE to function? Right now your pull request only has the "None" option in the SoftDevice menu.

Is this something you have run into? Do you have any example code that you are running on this module? Thanks again for your work in getting this device supported.

ncollins

@Jon-Raymond the nRF52805 should support the S112 and S113 soft device, but I removed it from the menu because I never tested it and didn't intend to immediately use it.

Digging through sandeepmistry/arduino-nrf5, it looks like S112 and S113 aren't included in the SDK. It might be easy enough to just drop in two new folders, then update boards.txt.

(Just an example of how I would add a soft device option to the dropdown, these would have to match up with whatever is in the sdk)

I would recommend opening an issue/question on https://github.com/sandeepmistry/arduino-nRF5, specifically asking the best way to add a new softdevice to the library. If it's straightforward, I can work with you to get those changes incorporated and, hopefully, included in the merge request.

Jon Raymond

Thanks @ncollins. I created the issue as requested.

ncollins

@Jon-Raymond Well, not seeing a lot of activity in the repo.

I took a very long shot at adding support https://github.com/nikolac/arduino-nRF5/tree/nrf52805-s112-support.

I was able to flash the softdevice, but I haven't tested or even uploaded a working sketch (sloppy). Feel free to mess around and test. If it works for you, I do the same for S113.

Biggest question I have is around figuring out the proper values for the "linker scripts" https://github.com/nikolac/arduino-nRF5/blob/nrf52805-s112-support/cores/nRF5/SDK/components/softdevice/s112/toolchain/armgcc/armgcc_s112_nrf52805_xxaa.ld

NeverDie

I've ordered an Adafruit Clue, which should be arriving today. It utilizes the nRF52840. Judging from the reviews, Adafruit has done a nice job of supporting both the Clue and the Clue's vast number of built-in sensors with 1. good adafruit library integration along with lots of example programs and 2. the adafruit bootloader, making it easy for beginners to program the Clue via the familiar Arduino IDE. For those just getting started, I think it's likely to be a more satisfying experience and a gentler introduction to nRF5x than buying a nRF5x DK and then wondering what to do next.

nRF5 action!

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