raspberry pi 4 nrf52840 adafruit bootloader

raspberry pi 4
sudo apt-get install openocd


openocd.cfg
adapter driver bcm2835gpio
bcm2835gpio_peripheral_base 0xFE000000
bcm2835gpio_speed_coeffs 236181 60
bcm2835gpio_swd_nums 25 24
transport select swd
set CHIPNAME nrf52840
source [find target/nrf52.cfg]
adapter speed 1000
init
targets
reset halt


SB1 soldered, SB2 cut


downloaded pca10059_bootloader-0.6.2.zip
extracted pca10059_bootloader-0.6.2_s140_6.1.1.hex


modified /usr/share/openocd/scripts/target/nrf52.cfg
#swj_newdap $_CHIPNAME cpu -expected-id $_CPUTAPID
swj_newdap $_CHIPNAME cpu -expected-id


sudo openocd
Open On-Chip Debugger 0.10.0+dev-00114-g41bcbc67d-dirty (2021-01-18-16:43)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Info : BCM2835 GPIO JTAG/SWD bitbang driver
Info : clock speed 1000 kHz
Info : SWD DPIDR 0x2ba01477
Info : nrf52840.cpu: hardware has 6 breakpoints, 4 watchpoints
Error: nrf52840.cpu -- clearing lockup after double fault
Info : starting gdb server for nrf52840.cpu on 3333
Info : Listening on port 3333 for gdb connections
target halted due to debug-request, current mode: Thread
xPSR: 0x01000000 pc: 0xfffffffe msp: 0xfffffffc
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections


telnet localhost 4444


targets
    TargetName         Type       Endian TapName            State
--  ------------------ ---------- ------ ------------------ ------------
 0* nrf52840.cpu       cortex_m   little nrf52840.cpu       halted


flash banks
#0 : nrf52840.flash (nrf5) at 0x00000000, size 0x00000000, buswidth 1, chipwidth 1
#1 : nrf52840.uicr (nrf5) at 0x10001000, size 0x00000000, buswidth 1, chipwidth 1


reg
===== arm v7m registers
(0) r0 (/32): 0x00000000
(1) r1 (/32): 0x00000000
(2) r2 (/32): 0x00000000
(3) r3 (/32): 0x00000000
(4) r4 (/32): 0x00000000
(5) r5 (/32): 0x00000000
(6) r6 (/32): 0x00000000
(7) r7 (/32): 0x00000000
(8) r8 (/32): 0x00000000
(9) r9 (/32): 0x00000000
(10) r10 (/32): 0x00000000
(11) r11 (/32): 0x00000000
(12) r12 (/32): 0x00000000
(13) sp (/32): 0xfffffffc
(14) lr (/32): 0xffffffff
(15) pc (/32): 0xfffffffe
(16) xPSR (/32): 0x01000000
(17) msp (/32): 0xfffffffc
(18) psp (/32): 0x00000000
(19) primask (/1): 0x00
(20) basepri (/8): 0x00
(21) faultmask (/1): 0x00
(22) control (/2): 0x00
(23) d0 (/64): 0x0000000000000000
(24) d1 (/64): 0x0000000000000000
(25) d2 (/64): 0x0000000000000000
(26) d3 (/64): 0x0000000000000000
(27) d4 (/64): 0x0000000000000000
(28) d5 (/64): 0x0000000000000000
(29) d6 (/64): 0x0000000000000000
(30) d7 (/64): 0x0000000000000000
(31) d8 (/64): 0x0000000000000000
(32) d9 (/64): 0x0000000000000000
(33) d10 (/64): 0x0000000000000000
(34) d11 (/64): 0x0000000000000000
(35) d12 (/64): 0x0000000000000000
(36) d13 (/64): 0x0000000000000000
(37) d14 (/64): 0x0000000000000000
(38) d15 (/64): 0x0000000000000000
(39) fpscr (/32): 0x00000000
===== Cortex-M DWT registers


nrf5 mass_erase
nRF52840-xxAA(build code: D0) 1024kB Flash, 256kB RAM
Flash protection of this nRF device is not supported
Failed to check chip's write protection


flash erase_check 0
successfully checked erase state
        Bank is erased


flash write_image /home/pi/openocd-config/bootloader.hex
Padding image section 0 at 0x00000b00 with 1280 bytes
Flash write discontinued at 0x00025de8, next section at 0x000f4000
SWD DPIDR 0x2ba01477
Failed to write memory at 0x20001948
Failed to write to nrf5 flash
error writing to flash at address 0x00000000 at offset 0x00000000