Example

One example of using pyripherals is an impedance analyzer which calculates the impedance of an unknown component. For this example you will need an Opal Kelly XEM7310 FPGA connected to your computer as well as a DAC80508 and ADS8686 connected to the FPGA (the ADS8686 is available on an eval kit and the DAC8058 could be mounted onto a VQFN4x4 breakout board). The pin connections between the FPGA on the XEM7310 and these peripherals are as follows:

DAC80508

• SDI - L3

• SDO - K3

ADS8686

• SDI - P2

• SDOA - N5

• SDOB - N2

Also download the top_level_module.bit bitfile, ep_defines, Registers.xlsx, and the impedance_analyzer.py Python file from the GitHub. Change the BITFILE_PATH constant in impedance_analyzer.py to the path of top_level_module.bit on your computer. Read through the documentation included in impedance_analyzer.py to understand the other constants you can change as well as the setup of the circuit. You can then run impedance_analyzer.py.

This will send a test voltage across the unknown impedance with the DDR3 and the DAC80508 and read it back using the DDR3 and the ADS8686. With the known resistor’s value, the current is calculated to be used with the read voltage to calculate the impedance.