March 29, 2015 – Alan C. Assis

Unfortunately NXP uses a built-in programmer in the LPCXpresso board called LPCLink that is not supported by OpenOCD and there is not (AFAIK) an option to replace its firmware.

Then I decided to cut the board to separate the “LPCXpresso LPC1115 REV A” from the LPCLink programmer.

So I used a simple and low cost STLink-v2 programmer board that is supported by OpenOCD. In order to use OpenOCD to reprogram the LPC1115 board we need to connect four wires from STLink-v2 to LPC1115 board:

STLink-v2    |   LPC1115 Board
------------------------------
GND              GND
3V3              3V3
IO               AD4
CLK              P0.10

Also we need to instruct OpenOCD to use SWD protocol. You can do it creating the following config openocd.cfg file:

# LPC1115 LPCXpresso Target

# Using stlink as SWD programmer
source [find interface/stlink-v2.cfg]

# SWD as transport
transport select hla_swd

# Use LPC1115 target
set WORKAREASIZE 0x4000
source [find target/lpc11xx.cfg]

Now execute OpenOCD using the created config file:

$ sudo openocd -f openocd.cfg 
Open On-Chip Debugger 0.9.0-dev-00251-g1fa4c72 (2015-01-28-20:08)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.sourceforge.net/doc/doxygen/bugs.html
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
adapter speed: 10 kHz
adapter_nsrst_delay: 200
Info : Unable to match requested speed 10 kHz, using 5 kHz
Info : Unable to match requested speed 10 kHz, using 5 kHz
Info : clock speed 5 kHz
Info : STLINK v2 JTAG v17 API v2 SWIM v4 VID 0x0483 PID 0x3748
Info : using stlink api v2
Info : Target voltage: 3.137636
Info : lpc11xx.cpu: hardware has 4 breakpoints, 2 watchpoints

Connect to OpenOCD server:

$ telnet 127.0.0.1 4444

Reset the CPU and flash the lpc1115_blink.bin file:

> reset halt
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0xc1000000 pc: 0x1fff0040 msp: 0x10000ffc

> flash probe 0
flash 'lpc2000' found at 0x00000000

> flash write_image erase blink_lpc1115.bin 0x00000000
auto erase enabled
target state: halted
target halted due to breakpoint, current mode: Thread 
xPSR: 0x01000000 pc: 0x10000108 msp: 0x100001b8
Verification will fail since checksum in image (0x00000000) to be written to flash is different from calculated vector checksum (0xefffebe9).
To remove this warning modify build tools on developer PC to inject correct LPC vector checksum.
wrote 4096 bytes from file blink_lpc1115.bin in 0.592621s (6.750 KiB/s)

> reset run

The checksum warning message could be removed if you add the checksum to binary, read this post: http://sigalrm.blogspot.com.br/2011/10/cortex-m3-exception-vector-checksum.html.

The blink LED sample I got from Frank Duignan’s page: http://eleceng.dit.ie/frank/arm/BareMetalLPC1114/index.html

Edit Makefile and configure LIBSPEC to point out to the right path:
LIBSPEC=-L /usr/lib/gcc/arm-none-eabi/4.8/armv6-m

$ make

To generate the final binary I used objcopy:

$ arm-none-eabi-objcopy -O binary main.elf blink_lpc1115.bin