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Why do I get 'undefined reference to "c-method" ' error when trying to load my matlab function to arduino uno?

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Tina on 9 Feb 2018
Commented: Noam Greenboim on 21 Oct 2020
Hi, I have a Simulink model containing a matlab function block. In this function two methods from my .c file are called, hc595_Init and hc595_SendData. These should set the selected pins as outputs and set them to low/high. When I try to download the simulink model to my arduino Uno I get the following error:
Error(s) encountered while building "Fan": ### Failed to generate all binary outputs
In the code generation report it says:
C:\Program Files\MATLAB\R2017b\Fan_ert_rtw/Fan.c:61: undefined reference to `hc595_Init' C:\Program Files\MATLAB\R2017b\Fan_ert_rtw/Fan.c:134: undefined reference to `hc595_SendData' collect2.exe: error: ld returned 1 exit status gmake: * [../Fan.elf] Error 1 C:\Program Files\MATLAB\R2017b\Fan_ert_rtw>echo The make command returned an error of 2 The make command returned an error of 2 C:\Program Files\MATLAB\R2017b\Fan_ert_rtw>An_error_occurred_during_the_call_to_make Der Befehl "An_error_occurred_during_the_call_to_make" ist entweder falsch geschrieben oder konnte nicht gefunden werden.
Can anybody tell me why this error occurs?
Tina on 12 Feb 2018
yes I do, this is my code of the mask:
function sendToHC595(data, serPin, sckPin, rckPin, gPin)
persistent initflag;
if strcmp(, 'rtw'),
if isempty(initflag),
% initialise output pins and send data to HC595 ic
coder.ceval('hc595_Init', serPin, sckPin, rckPin, gPin);
initflag = 1;
% send data to HC595 ic
coder.ceval('hc595_SendData', data, serPin, sckPin, rckPin);
% send data to HC595 ic
coder.ceval('hc595_SendData', data, serPin, sckPin, rckPin);

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Accepted Answer

Shashank on 13 Feb 2018
You need to add the your .c and .h files in the Simulation Target pane of the Configuration parameters of the model. Here is the exact procedure you need to follow:
Hope this helps.
- Shashank
Noam Greenboim
Noam Greenboim on 21 Oct 2020
If you generate C code from the simulink model, be sure to check "Use the same custom code settings as Simulation Target" under Code generation --> Custom code (in Configuration Parameters window).

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