How do I access variables like $PROGNAME or $BUILD_DIR in an openocd .cfg file?

Development Platforms
1

Is it possible to do this? I would like to access these values from inside a target .cfg file, but I can’t figure out any way to get this to work. Is there something equivalent to Import(“env”) that could work in a .cfg file?

I tried this

if { [info exists BUILD_DIR] } {
set myBuild $BUILD_DIR

but no luck there.

I would like to get the BUILD_DIR and PROGNAME and PROG_SUFFIX so it can be used in an openocd flash write command. Currently I have to hard code the entire path and filename like this:

set IMGFILE “C:\Users\tony\Documents\PlatformIO\Projects\TGBlinky2.pio\build\lpc1769\firmware.bin”
flash write_image erase $IMGFILE 0x0 bin

I’m looking for a way to send the path and filename from platformio so I don’t have to keep changing that .cfg file for every project.

Could someone tell me if this can be done and how?

Oh…and the reason for all this is that I need to create a custom upload command to get openocd to use an ST-Link tool to program an debug LPC17xx chip.

2

You can completely control the OpenOCD invocation yourself using either Advanced scripting or the upload_command. So you can inject -c "set IMGFILE ..." flags from inside there that you can reference in custom config files.

3

Thanks Max, that works for me.

I have another hurdle…how do you inform the linker that you want the compiled code to start at an offset address( say like 0x00004000 ) instead of whatever the default may be ?

4

That is very dependent on the used platform. If you’re using the PlatformIO provided NXPLPC platform, then

the upload respects the offset_address information, so you can add

board_upload.offset_address = 0x00004000

to the platformio.ini.

5

I’m using platform “nxplpc-arduino-lpc176x” and it doesn’t have those lines in builder/main.py.
But I did try add the command to upload_flags like this:
upload_protocol= custom
upload_command = $PROJECT_PACKAGES_DIR\tool-openocd\bin\openocd
upload_flags =
-c
set LOADADDRESS 0x00004000
-c
set FIRMWARENAME {$PROJECT_DIR$SOURCE}
-f
$PROJECT_PACKAGES_DIR\tool-openocd\scripts\board\lpc1769_upload.cfg

which for some reason does not pass the upload_flags with the upload_command unless I call an extra_script that does this:

env.Replace(
UPLOADER="$PROJECT_PACKAGES_DIR\tool-openocd\bin\openocd",
UPLOADCMD="$UPLOADER $UPLOADERFLAGS"
)

This finally makes it work!
But…then there is another issue.
The code gets placed at the LOADADDRESS I defined at 0x00004000 (verified with TelNet dumping memory). However, the LPC chips need the vector table to be at 0x00000000 and when I checked, it was all empty (0xff bytes) up till the load address at 0x00004000.
So the code will not execute!

If I examine the program code at 0x00004000, it has the vector table starting right at 0x00004000.
How do we tell the compiler/linker to place the vector table at 0x00000000 when the actual program code is at the given offset address?

6

Well yes the point of moving the application upwards in flash is that the chip contains a bootloader that sits at 0x0 and that then loads the application from the pre-agreed offset. What bootloader have you flashed on your chip?

7

Well, no bootloader actually, thanks for pointing that out!
I mistakenly thought I could use a command like “mww 0xE000ED08 $_LOADADDRESS”
where 0xE000ED08 is the vector table offset register on the LPC1769 chip.
I figured a reset would then jump to the vector table with the offset applied. But I realize now that doesn’t work.
The chip is built to start at address 0x00000000 after reset (unless the BOOT0 pin is low, which starts the chip’s own bootloader).