There are main options for programming nRF52540 boards, and these are well documented at https://github.com/joric/nrfmicro/wiki/Bootloader. To program the tornblue I used a ST-Link/V2 with the Blackmagic firmware on OS X.
To install the blackmagic firmware on the ST-Link/V2 you need to first download and compile the following tool and firmware:
- https://github.com/UweBonnes/stlink-tool/tree/stlinkv21
- https://github.com/blacksphere/blackmagic/tree/master/src/platforms/stlink
Install the blackmagic firmware on the ST-Link/V2 using:
$ ./stlink-tool/stlink-tool blackmagic/src/blackmagic.bin
Firmware version : V2J31S7
Loader version : 14152
ST-Link ID : 52FF68064885555248171987
Firmware encryption key : A32E6E6E82ADAF7D99EBD574CB4C784D
Current mode : 1 Loaded firmware : blackmagic/src/blackmagic.bin, size : 97332 bytes
................................................................................................
Like many ZMK boards Tornblue uses the Adafruit_nRF52_Bootloader. I modified this for tornblue so that one LED is enabled in the bootloader. You can download this version from https://github.com/rtitmuss/Adafruit_nRF52_Bootloader.
Compile the bootloader using:
$ make BOARD=tornblue
You can find the compiled bootloader at:
_build/build-tornblue/tornblue_bootloader-0.6.3-49-gbfd3b24.out
You can connect the programmer to the tornblue using a SOIC connector. Connect the SWD pads on the PCB to the 20 pin JTAG header on the ST-Link/V2 as follows:
| PCB SWD | ST-Link/V2 |
|---|---|
| 3.3V | VCC Pin 1 |
| SWD IO | SWDIO Pin 7 |
| SWD CLK | SWCLK Pin 9 |
| GND | GND Pin 8 |
The pinout on the ST-Link/V2 20 pin JTAG header is:
You always need to setup the ST-Link/V2 after it has been powered up using:
./stlink-tool/stlink-tool
When the ST-Link/V2 is first connected all the three green LEDs on the Tornblue may all be lit.
You can first check the that board is correctly connected using swdp_scan as shown below. You may need to update the /dev path.
$ arm-none-eabi-gdb --batch -ex "target extended-remote /dev/cu.usbmodem14101" -ex "mon swdp_scan"
Target voltage: 3.30V
Available Targets:
No. Att Driver
1 Nordic nRF52 Access Port (protected)
You can then program the bootloader, using:
$ arm-none-eabi-gdb --batch -ex "target extended-remote /dev/cu.usbmodem14101" -ex "mon swdp_scan" -ex "file tornblue_bootloader-0.6.3-49-gbfd3b24_s140_6.1.1.hex" -ex "att 1" -ex "mon erase" -ex load
Target voltage: 3.30V
Available Targets:
No. Att Driver
1 Nordic nRF52 Access Port (protected)
warning: while parsing target description: no element found
warning: Could not load XML target description; ignoring
warning: while parsing target memory map (at line 1): Required element <memory> is missing
0xbfefed14 in ?? ()
Loading section .sec1, size 0xb00 lma 0x0
Loading section .sec2, size 0xf000 lma 0x1000
Loading section .sec3, size 0x10000 lma 0x10000
Loading section .sec4, size 0x5de8 lma 0x20000
Loading section .sec5, size 0x85b4 lma 0xf4000
Loading section .sec6, size 0x58 lma 0xfd800
Loading section .sec7, size 0x8 lma 0x10001014
Start address 0xfafcc, load size 188156
Transfer rate: 418 KB/sec, 969 bytes/write.
[Inferior 1 (Remote target) detached]
I found that I needed to program the bootloader twice for it to be successful.
$ arm-none-eabi-gdb --batch -ex "target extended-remote /dev/cu.usbmodem14101" -ex "mon swdp_scan" -ex "file tornblue_bootloader-0.6.3-49-gbfd3b24_s140_6.1.1.hex" -ex "att 1" -ex "mon erase" -ex load
Target voltage: 3.30V
Available Targets:
No. Att Driver
1 Nordic nRF52 M4
2 Nordic nRF52 Access Port
0xfffffffe in ?? ()
erase..
Loading section .sec1, size 0xb00 lma 0x0
Loading section .sec2, size 0xf000 lma 0x1000
Loading section .sec3, size 0x10000 lma 0x10000
Loading section .sec4, size 0x5de8 lma 0x20000
Loading section .sec5, size 0x85b4 lma 0xf4000
Loading section .sec6, size 0x58 lma 0xfd800
Loading section .sec7, size 0x8 lma 0x10001014
Start address 0xfafcc, load size 188156
Transfer rate: 31 KB/sec, 959 bytes/write.
[Inferior 1 (Remote target) detached]
When the booloader has been successfully installed then the a single green LED will be lit.