Software defined lab power supply

Sometimes in the lab there is need to monitor the power parameters during some period of time and put it on a nice graph.

Because I couldn't find something like this and because it is fun to make things, I start to wonder what if I put an Arduino on a power supply!

So, the lab supply must have:

-Variable voltage between 1- 14.4V

-Current monitor

-Start/Stop

-Overcurrent protection

-Serial output with time markers

Because I am lazy, I used some ready-made modules.

The main power supply is a modified 12V/5A SMPS; with a little tweak it now deliver 17V/4A.

The modification was made in the feedback circuit where the TL494 reference is compared with the output voltage.

The variable output voltage is made with a DC/DC Step down module able to handle constant voltage from 1.25 to Vsmps - 2V at around 5 A.

The output voltage and current are measured with the Arduino ADCs and I used two 2.5 LM4050 precision shunt reference in series to have Aref at 5V. 

The DC/DC Step down is controlled with a PCF optocoupler driven by a digital potentiometer MCP41010 on SPI.

The output relay is used for fast protection as a "crowbar" circuit and, in the future, will connect the output  to a controlled discharge circuit to characterise batteries.

By code, this power supply can be used to deliver regulated voltage and monitor the current or to charge various batteries.

The schematic:

The code is on Github.