GUIDE - NRF5 / NRF51 / NRF52 for beginners

[nagelc]

Hi @electrik

You can program these ibeacons to work with MySensors.
I reprogrammed one by soldering some wires to a jlink adapter. Not elegant, but it worked.
Some type of push pin setup would be good if you are going to actually use these modules.

The version I got had only a button on the board, and no way to easily add any other sensors, so they weren't very useful. It would be interesting to try the ones with the temperature and acceleromator.

[abelson]

I am using a generic nRF52 dev board with the Arduino nRF52 core. I am trying to get a sample BLE service to display, but it cannot find it on my BLE scanner. After I couldn't get that to work, I decided to make the code even simpler. Since the dev board that I am using has a serial USB out I thought I would just check if I could get a "Hello World!" to the serial monitor... After flashing the soft device, I still couldn't get any output on my serial monitor.

Open On-Chip Debugger 0.10.0-dev-00254-g696fc0a (2016-04-10-10:13)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
debug_level: 0
0x4000
adapter speed: 10000 kHz
nrf52.cpu: target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0x61000000 pc: 0x0001b08e msp: 0x20001188
nrf52.cpu: target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0xfffffffe msp: 0xfffffffc
** Programming Started **
auto erase enabled
nrf52.cpu: target state: halted
target halted due to breakpoint, current mode: Thread 
xPSR: 0x61000000 pc: 0x2000001e msp: 0xfffffffc
wrote 114688 bytes from file C:\Users\Admin\Documents\ArduinoData\packages\sandeepmistry\hardware\nRF5\0.7.0/cores/nRF5/SDK/components/softdevice/s132/hex/s132_nrf52_2.0.1_softdevice.hex in 2.559271s (43.762 KiB/s)
** Programming Finished **
** Verify Started **
nrf52.cpu: target state: halted
target halted due to breakpoint, current mode: Thread 
xPSR: 0x61000000 pc: 0x2000002e msp: 0xfffffffc
nrf52.cpu: target state: halted
target halted due to breakpoint, current mode: Thread 
xPSR: 0x61000000 pc: 0x2000002e msp: 0xfffffffc
verified 110636 bytes in 0.372659s (289.924 KiB/s)
** Verified OK **
** Resetting Target **
shutdown command invoked

I am using OpenOCD and an ST-Link v2 to upload my code and it looks like it is uploading successfully. Here is the output when I try to flash the S132 soft device:

void setup() {
  Serial.begin(9600);
  Serial.println("Starting...");

}

void loop() {
  Serial.println("Hello World!");
  delay(1000);

}

I also tried running this code with the MySensors library:

#define MY_RADIO_NRF5_ESB
#include <MySensors.h>

void setup() {
  Serial.begin(9600);
  Serial.println("Starting");
}

void loop() {
  Serial.println("Hello World!");
  delay(3000);
}

And got this error:

In file included from C:\Users\Admin\Documents\ArduinoData\packages\sandeepmistry\hardware\nRF5\0.7.0\cores\nRF5/Arduino.h:5:0,
                 from sketch\MyBoardNRF5.ino.cpp:1:
c:\users\admin\documents\arduinodata\packages\sandeepmistry\tools\gcc-arm-none-eabi\5_2-2015q4\lib\gcc\arm-none-eabi\5.2.1\include\stdint.h:9:26: fatal error: stdint.h: No such file or directory
compilation terminated.
exit status 1
Error compiling for board MyBoardNRF5 nRF52832.
Error while flashing SoftDevice.
java.io.FileNotFoundException: C:\Users\Admin\Documents\ArduinoData\packages\MySensors\hardware\nRF5\0.3.0\softdevices.txt (The system cannot find the file specified)

[monte]

@abelson first you have to flash SD and then chose softdevice in board options and flash your sketch.
It seems that you are lacking softdevice binary. It seems that your version of sandeepmistry's NRF5 core is pretty outdated, you have 0.3 version when surrent version is 0.7. No wonder that links to softdevice binaries are broken in softdevices.txt. Try updating core to the latest version and/or downloading softevice binary from nordic's site yourself.

[abelson]

@monte that makes sense. Do you know what options I have to do to flash the sketch after I flash the soft device? If I get the above output that I posted, does that mean that the soft device flashed successfully?

[monte]

@abelson no. You need to have softdevice binary on your PC to flash it to NRF board. Please, read my answer above and try to do, what I suggested.

You need to choose softdevice option if it has been flashed to the board.

[electrik]

This post is deleted!

[electrik]

@BearWithBeard
Great explanation, thanks!
On my windows 10 installation I had to run Zadig to make the programming from platformIO work.

[electrik]

@BearWithBeard
What did you do to get the serial pins of the Ebyte development board configured correctly, when using the generic board variant in platformIO? I've copied MyBoardNRF5.cpp but this is not used it seems.
Also redefining the definitions from variant.h

#define PIN_SERIAL_TX (11)
#define PIN_SERIAL_RX (12)

doesn't give serial output.

[BearWithBeard]

@electrik Yeah, I ran into that issue, too. Not sure if that's the proper way to solve it, but I add a custom board directory to the build flags in platformio.ini ...

build_flags = 
	-I $PROJECT_DIR/boards/generic

... and copied the board variant files from .platformio/packages/framework-arduinonordicnrf5/variants/Generic/ to boards/generic/ in my project folder. Changes made in here aren't ignored or overwritten by global PIO definitions.

[electrik]

@BearWithBeard Thanks that did it.
Could it be the TX and RX are switched on the BMP in your post?

[BearWithBeard]

@electrik Good to hear. And yes, I think you are right. I'll swap them and change the naming to RXI and TXO to clarify the directionality. Thanks for the hint!

[Ivanli]

Great post, thanks a lot for sharing.

[nagelc]

With respect to initial erase of NRF52, I have been using @BearWithBeard Black Magic Probe instructions successfully for years. But, my latest set of Minew boards doesn't respond.
I found that there is a new lock procedure from Nordic:

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/working-with-the-nrf52-series-improved-approtect

I have tried upgrading my gdb and also J-Link EDU and nrfjprog tool chains and have not successfully connected to the new boards yet.

Has anyone had success with unlocking one of these new boards?

[NeverDie]

@nagelc Sorry I don't have an informed answer, but thanks for posting and making us aware of your experience with the minew's! Haven't heard from you in a while. Have you tried upgrading the firmware on the J-link that's part of a DK? I can't say that I have, but the firmware upgradeability was one of the alleged selling features of a DK's J-Link. That potential upgradeability didn't ever seem to matter, but maybe now it does.

As for me, after a long break I'm back to have a run at getting the nRF52805 to work. So far I've got bare metal blinking and bare metal UART working. I'm opting for bare metal code because it's unclear how well anything else will work with the nRF52805, which doesn't seem all that well supported. Soon to get some basic bare metal proprietary radio working, I hope.... If successful, I'll post it to github to memorialize it. There are surprisingly few examples of bare metal code out there, even though that's all the datasheet itself talks about. I guess I can understand why, because I've found some surprising ambiguities in the datasheet. For instance, who would have thought that PSELTXD would refer to an actual pin number and not to a bitmask? From the datasheet I thought for sure it would be a bitmask (like nearly everything else in the datasheet), but no, it's the actual pin number. I mean, why does the datasheet show literally every bit of a 32 bit word is relevant for specifying the pin number? On a different issue, bare metal UART doesn't work quite right without some artificial delays, even if driven by interrupt events, apparently because the actual generated baudrates aren't exactly right (something the datasheet admits). So, there's some finessing involved that you don't see when you're only working from abstracted libraries.

Regardless, the architecture itself remains pretty cool, and I enjoy it a lot!

[nagelc]

After correcting a wiring error (duh!) I was able to erase using my J-Link Mini EDU.
I used Nordic's nrfjprog:
nrfjprog --family NRF52 --recover
nrfjprog --family NRF52 --recover

I had to run it twice to get the unlock. I think this makes sense after reading the devzone article.
Once unlocked, I could use my black magic probe for programming. I expect the blackmagic folks haven't had time to adapt to the new lock scheme yet.

[nagelc]

@NeverDie Interesting chip for a sensor node. All the other NRF52s have way more capability than we are likely to use in a low power sensor node. The 52805 seems to have just enough. Hope you are able to make some progress.

[NeverDie]

@nagelc said in GUIDE - NRF5 / NRF51 / NRF52 for beginners:

After correcting a wiring error (duh!) I was able to erase using my J-Link Mini EDU.
I used Nordic's nrfjprog:
nrfjprog --family NRF52 --recover
nrfjprog --family NRF52 --recover

I had to run it twice to get the unlock. I think this makes sense after reading the devzone article.
Once unlocked, I could use my black magic probe for programming. I expect the blackmagic folks haven't had time to adapt to the new lock scheme yet.

For future reference, yet another way you can also erase your chip is using the "Programmer" app that you can install into "nRF Connect for Desktop" program. Just connect and press the "Erase All" button:

I find that I have to do this in order to unlock the chip for the first time prior to enabling the reset pin with the code:

  // Note: if chip has never been mass erased, then most likely PSELRESET[0] and PSELRESET[1] are both zero.
  // When that is the case, the chip is locked and neither can be set to 21.
  if (((NRF_UICR-> PSELRESET[0])==0xFFFFFFFF) && ((NRF_UICR-> PSELRESET[1])==0xFFFFFFFF)) { //if the two RESET registers were erased by a mass erase
    NRF_NVMC->CONFIG=1;  // Write enable the UICR
    //Note:  BOTH registers must be set to 21, or else PIN00.21 will not function as a RESET pin.
    NRF_UICR-> PSELRESET[0]= 21;  //designate pin P0.21 as the RESET pin
    NRF_UICR-> PSELRESET[1]= 21;  //designate pin P0.21 as the RESET pin
    NRF_NVMC->CONFIG=0;  // Put the UICR back into read-only mode.
  }

[NeverDie]

Well, I take it back. Although the above method worked for doing an "erase-all" and unlock the nRF52832 that's built into the nRF52-DK, it isn't doing anything to unlock a nRF52805 that's externally connected to an nRF52-DK. "Erase all" does seem to erase the program that on the nRF52805, but it nonetheless doesn't allow access to the reset registers NRF_UICR-> PSELRESET[0] and NRF_UICR-> PSELRESET[1]. I say that because, for instance, NRF_UICR-> PSELRESET[0] and NRF_UICR-> PSELRESET[1] are still zero after the "erase all" instead of 0xFFFFFFFF, and attempting to write them both to 21 fails.

I also tried nrfjprog:
nrfjprog --erase all
nrfjprog --recover
nrfjprog --resetpinenable
nrfjprog --family NRF52 --recover
nrfjprog --family UNKNOWN --recover
nrfjprog --eraseuicr

and after each try the nRF52805 still has the reset registers impervious to writing.

Well, I see that the nRF52805 has been blessed with some kind of fancy new access port protection (APPROTECT), but reading the value of NRF_UICR->APPROTECT, it is currently at 0xFFFFFFFF, which means that APPROTECT is disabled.

So, not sure what to do about this one.

[NeverDie]

For anyone who may be interested, this is what the current draw on an nRF52805 looks like when it's sleeping:

It's about the same whether it's using DCDC mode or LDO mode when the system is sleeping in ON mode. When I first saw this plot I thought the MCU was waking up, doing something, and then falling back to sleep on what seemed like a very repeatable periodicity. I even went hunting for some part of the system that I had forgotten to turn-off that might be causing this behavior. However, when that hunt didn't turn up anything, my present theory is that this is just how the low power mode works when the system is ON but in sleep mode: it maybe is more efficient to sip current at periodic intervals than it is to run the LDO/DCDC continuously.

Now that you've seen the above picture of the spikey nature in which a nRF52 module draws its sleep current, you can appreciate that using a uCurrent Gold or a Current Ranger (let alone a multimeter) to measure sleep current is likely to give an erroneously low measurement: these pulses pass by too quickly for such a meter to properly register. That's why, for instance, I began to suspect that this guy's measurements were possibly too low:
https://www.youtube.com/watch?v=7sMbcyYS9os

Indeed, when I hook my same sleeping module up to a current ranger, the current ranger shows 0.0ua when set in ua mode. In na mode, though, the measurements are jumping around all over the place. The point being: if that was all I had to go on, I'd probably erroneously conclude that the sleep current was something less than 1ua, whereas the PPK2 here is reporting an average 5.3ua within its measurement window.

What remains unexplained is why the average current draw I measured with PPK2 while sleeping like this is so high. According to the nRF52805 datasheet, the current drawn while sleeping in system ON mode with full memory retention should be just 0.8ua.

and so I'm not sure why I'm experiencing so much more than that (5.3ua in this PPK2 example), unless maybe it's something about the Fanstel BC805M module that it's a part of which is raising the sleep current. If so, that would certainly be disappointing: I bought it precisely because the nRF52805 is supposed to have such a low sleep current compared to the other Nordic nRF52 chips that are out there.

As a matter of fact, the spikey nature of the current draws led me to wonder whether maybe the PPK2 itself was perhaps not measuring the current correctly. So, to answer that, I added a 220uF bypass ceramic capacitor (i.e. between VCC and GND) near the nRF52805 module to better average out the current draw seen by the PPK2, and then I measured using the PPK2 again. Guess what? Now the PPK2 measures an average of 0.81ua, which is spot-on with what the datasheet predicted. Whew! What a relief. I find this new measurement trustworthy not only because (a) it agrees with the value predicted by the datasheet, but now also (b) both a PPK2 and a Current Ranger produce current measurements that agree with one another, and (c) by averaging out the current draw, the potential problems stemming from a highly spikey measurement are cast aside.

[monte]

@NeverDie have you checked the radio already? How much work is needed to make it work with mysensors?