Reflectance module on FPGA

[spalinowy]

Hello everyone,

I'm trying to read the signal from the QTRX HD 11RC module, but it's not working for me and I don't know why. On the oscilloscope I can only see the pulses that charge the capacitor, but there is no return signal. By chance I was able to read the signal, but interestingly in analog, not digital. But the analog option is out of the question due to the small number of analog channels in myRIO.
Does anyone have an idea how to improve the code to read informations from sensors?

[Bob_Schor]

As I read the Data Sheet on this device, it is designed to be read with an A/D Converter!  The myRIO has 10 A/D inputs, if I remember correctly, or you could use a USB Multi-function device.  Finally, the Manufacturer provides an Arduino library that you might be able to interface between the myRIO and this device.  I'm not an Engineer, but the Digital method they suggest sounds a little kludgy to me ...

Bob Schor

[spalinowy]

Thank you for your response.
I, on the other hand, do not see that the RC version of the module needs an ADC. The A version does.

Each sensor option is available in two output types: an “A” version with analog voltage outputs between 0 V and VCC, and an “RC” version with outputs that can be read with a digital I/O line on a microcontroller by first setting the lines high and then releasing them and timing how long it takes them to read as low (typically anywhere from a few microseconds to a few milliseconds). The lower the output voltage or shorter the voltage decay time, the higher the reflectance. The following simplified schematic diagrams show the circuits for the individual channels: