MPR121 Sensor (I2C Support)


I try to make the MPR121 Object run with the Akso, without success.

The patcher-output says " mpr121(0x5A) i2c error " The sensor is connect to PB9 & PB8
Is I2C supported at these pins?

The Patch itself is pretty simple (The same setup on my Axoloti is working like a charm)


Interesting. Would you share the patch for the axoloti?
Best regards, Markus

Hi @sphynx

it’s exacatly what’s in picture above. All objects are straight from the patcher

btw: here is the full error message:

USB device found
Connected to device.
Firmware version on attached device:, crc=0x9922E990
Generate code complete
Compiling patch.
Der Befehl "sed" ist entweder falsch geschrieben oder
konnte nicht gefunden werden.
process_begin: CreateProcess(NULL, sed -n s/^\/\/$MODULES=\(.*\)/\1/gp ../build/xpatch.cpp, ...) failed.
Makefile.patch:98: pipe: No such file or directory
process_begin: CreateProcess(NULL, sed -n s/^\/\/$MODULE_DIRS=\(.*\)/\1/gp ../build/xpatch.cpp, ...) failed.
Makefile.patch:99: pipe: No such file or directory
Memory region         Used Size  Region Size  %age Used
            SRAM:        4828 B       384 KB      1.23%
           SRAM2:          32 B         8 KB      0.39%
           SRAM3:        1896 B       118 KB      1.57%
         CCMSRAM:        2452 B       116 KB      2.06%
           SDRAM:          0 GB        32 MB      0.00%
done ../build/xpatch
Done compiling patch.
mpr121(0x5A) i2c error

Well I just do not want to click around.
Since 0x5a is the default address of the MPR121…maybe ths thread can help you

Best, M

The error message is : “The “sed” command is either misspelled or
could not be found.” (according to Google translate) Looks like you need to install sed (the Posix stream editor) or fix the PATH so it is found.

Hope this helps.


1 Like

Hi @jcgriggs

Sed is installed and also the path is correct.
Very strange :face_with_monocle:

Sorry, I know software development in general, but not the Axso build system particularly. If the PATH is correct for sed from the command line, something in the build system is overriding or ignoring it. It seems to me that it is the CreateProcess call raising the error about sed and the pipe errors are attempts to execute whatever CreateProcess outputs. I’m also guessing all of this is related to the i2c error at the end, but there’s no guarantee that that is the case. My wild assed guess would be that sed is being used to parse the i2c device address from a file, but that is really going out on a limb in terms of the actual evidence.