QSP32 Solar Boost

Two devices, the LCD shown above and a trio of sensors in one package, are communicating over the I2C bus at the same time. I captured the SDA (data, red) and SCL (clock, yellow) clock signals while both devices were running.

For fun, I used a Saleae logic analyzer to poke at this signal. We can see the address of the sensor 0x76 and an 8 second delay that I programmed into the sketch. Unsurprisingly, the logic analyzer correctly recognizes these signals as I2C!

I successfully validated the I2C communication on a Quilter-designed board, confirming proper functionality with two devices connected to the bus.

Energy harvesting happens through the BQ25504: a boost converter designed to acquire and manage micro or milliwatts generated from devices like a solar panel. I validated functionality with a small (~1.25” x 2”) solar panel with an open circuit rating of 3.4V and 2.2V maximum power point (V @pmpp) and a 470uF polarized capacitor rated for 6.3V.

I placed the probes on the capacitor to demonstrate charging via a solar panel through an energy harvesting chip. This is a simple setup for capturing solar energy.

The capacitor charges and discharges rapidly and although this video is sped up by 1000X you can see the functionality clearly.

Next up: I2C communication

We recently added support to Quilter for differential pairs and I could not wait to try the feature out on the QSP32 Solar Boost!

When I uploaded my schematic, Quilter automagically detected the pairs between USB and UART.

Quilter did a great job of placing the FTDI chip close to the USB-C connector.

I put probes on DP_P and DP_N (white arrows). These traces go between a UART chip (top) and a USB-C connector (bottom). The layout of the differential pairs have precise length matching for good signal integrity.

Take a look at these perfectly mirrored signals! This feature works perfectly, I had three boards fabbed and each one connects instantly to upload sketches.

Next up: energy harvesting from a tiny solar panel