Revision 1 finally done (and for sale)

A project log for USB type-C power meter

A low-cost ($20) bidirectional USB-C power meter 5-20V 0-5A

muxmux 08/07/2017 at 12:130 Comments

Revision time! A little while ago I uploaded a video where I worked on the revision 1 schematic and layout, and after quite a long wait for the displays as well as about 2 weeks of on-and-off coding on the firmware, it's finally finished. 

As it turns out, the MOSFET and resistor approach I used to calibrate the input offset of the current shunt amplifier was not really ideal. The resistor I used to short out the amplifier was actually introducing an additional (significant) error, so I've done a bunch of testing to find out how to salvage this anyway. I ended up having to change out the resistor and MOSFET to both be lower-resistance, which fortunately got them completely in-spec. 

Also, shipping times from China are very variable. Whereas my first couple of OLED displays were here within a week, this shipment took a month. I hate sourcing from China for this reason, it's so hard to plan products.

Anyway, here's a little update video and if you like the project, check out the schematic and documentation on