photodiode configuration and signal mismatch

Main aim, I want to transmit signal from LED to Photodiode. So I have designed a basic diagram in Simulink.

But it shows some error message that

Error compiling Simscape network for model untitled.

Caused by:

• ['untitled/Photodiode']: Type mismatch in signal connection to W. Source signal type is {[1x1 double], 'W'} and destination signal type is {[1x1 double], 'W/m^2'}.
• Light_Emitting_Diode.W = {[1x1 double], 'kW'}
• Photodiode.W = {[1x1 double], 'kg/s^3'}

Please help me out to configure to match the signal.

Kindly refer to attached figure.

Parameters:

LED: 1) Battery 6V

Photodiode: 1) Battery 6V 2) Res= 100Ohms

Thank you

[Jyotsna Talluri]

Can you attch your model instead of sharing screenshot so that I can simulate and reproduce the error

Answer 1

[Joel Van Sickel]

Hello Vasavi,

your problem makes sense at it would seem those two blocks were designed to work together, unfortunately, they weren't. Those signals are 2 different units. The output of the LED is in watts, while the input of the photodiode in watts per meter squared. You need to divide the output of the LED by meters squared. you could do this using a PS gain block and set units to 1/m/m. However, you probably need to pick a small area for this to work.

Here is an example of a photodiode being used:

https://www.mathworks.com/help/physmod/sps/examples/microcontroller-with-gpio-adc-and-dac-connections.html

Regards,

Joel