nrf52840: crash running heartrate example

[deadprogram]

I tried to run the heartrate example with the latest dev branch of both this package and TinyGo, only to discover that it crashes:

$ tinygo flash -size short -target itsybitsy-nrf52840 -monitor ./examples/heartrate
   code    data     bss |   flash     ram
  41216    1464    4680 |   42680    6144
Connected to /dev/ttyACM0. Press Ctrl-C to exit.
Sread error: Port has been closed

Some println() debugging seems to indicate that this the line where it crashes:
https://github.com/tinygo-org/bluetooth/blob/release/examples/heartrate/main.go#L60

Changing that line to

return uint8(min)

allows the example to execute as expected.

Calling rand.Intn() function from a normal serial program without softdevice does not cause any problems.

Running the heartrate example on HCI or Linux does not cause any problems either.

I also experience this same crash on most recent TinyGo release.

[deadprogram]

I experienced problem also on pca10040 board:

$ tinygo flash -size short -target pca10040-s132v6 -monitor ./examples/heartrate
   code    data     bss |   flash     ram
  38624    1356    4588 |   39980    5944
Open On-Chip Debugger 0.12.0
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
swd
Info : J-Link OB-SAM3U128-V2-NordicSemi compiled Jan  7 2019 14:07:15
Info : Hardware version: 1.00
Info : VTarget = 3.300 V
Info : clock speed 1000 kHz
Info : SWD DPIDR 0x2ba01477
Info : [nrf51.cpu] Cortex-M4 r0p1 processor detected
Info : [nrf51.cpu] target has 6 breakpoints, 4 watchpoints
Info : starting gdb server for nrf51.cpu on 3333
Info : Listening on port 3333 for gdb connections
[nrf51.cpu] halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000a80 msp: 0x20000400
** Programming Started **
Info : nRF52832-QFAA(build code: E0) 512kB Flash, 64kB RAM
Warn : Adding extra erase range, 0x0002fc30 .. 0x0002ffff
** Programming Finished **
** Resetting Target **
shutdown command invoked
Connected to /dev/ttyACM0. Press Ctrl-C to exit.
BBBstarting
tick 00:00.009
SoftDevice assert
starting
tick 00:00.009
SoftDevice assert
starting
tick 00:00.009
SoftDevice assert
starting
tick 00:00.009
SoftDevice assert

The program does not crash, but it does not correctly publish the heart rate notifications. This same board does work correctly when running the scanner example.

[deadprogram]

Further update: nrf51 does not appear to work at all at present as an Advertiser.

[deadprogram]

@aykevl perhaps you could please take a look?

[bgould]

I tried to run the heartrate example with the latest dev branch of both this package and TinyGo, only to discover that it crashes:

$ tinygo flash -size short -target itsybitsy-nrf52840 -monitor ./examples/heartrate
   code    data     bss |   flash     ram
  41216    1464    4680 |   42680    6144
Connected to /dev/ttyACM0. Press Ctrl-C to exit.
Sread error: Port has been closed

I am also able to reproduce this using tinygo.org/x/bluetooth@dev with the latest release (0.35.0) of TinyGo:

$ go get tinygo.org/x/bluetooth@dev

$ tinygo version
tinygo version 0.35.0 windows/amd64 (using go version go1.23.4 and LLVM version 18.1.2)

$ tinygo flash -target feather-nrf52840 -monitor tinygo.org/x/bluetooth/examples/heartrate
Connected to COM12. Press Ctrl-C to exit.
Sread error: Port has been closed: The I/O operation has been aborted because of either a thread exit or an application request.

[bgould]

I believe math/rand.Intn ends up delegating to machine.GetRNG - https://github.com/tinygo-org/tinygo/blob/52983794d702af7a00833ae12b0d2e7175e46017/src/machine/machine_nrf.go#L323

If that is true, I wonder if the crash here is similar to the root cause of tinygo-org/tinygo#4170