ESP32 NTP Clock

The boards from OSHPark came back and they work just fine. Shorting the boot pads while applying power puts it into the firmware loading mode as expected and the firmware worked the same as it did on the prototype.

Moreover, the board fits just fine in the 3D printed case. That was simply a modified version of the GPS clock case, with some of the lettering changed, one of the button holes removed, the antenna hole removed and the power hole elongated to accommodate a USB-C jack.

I am going to order a v1.1 board. It will move the ESP closer to the USB jack just to cut down on the trace lengths and replace the TVS diode with a USB protection diode array that protects the data lines as well as the VUSB. When that comes back and is tested I'll probably get some assembled and add them to the store.

I was able to figure out how to do the configuration UI. Pressing the "setup" button will display "SEtuP" on the display and create a WiFi network called "ESPClock". Connect to that and then surf to the web page at 192.168.4.1 and you'll get a form to put in the SSID, password, hostname NTP server and set things like 12/24 hour mode, enabling or disabling the 10th of a second digit and setting the mode for the colons.

I was also able to perform a rudimentary accuracy check on the clock. I took some slow-motion videos of the ESP clock prototype next to one of my GPS clocks. The iPhone slo-mo video seems to me to be running at about 120 FPS or so, so any given frame is maybe 8 ms or so away from its neighbor. Immediately after startup, the two clocks were changing the tenth-of-a-second digit about 6 frames apart, which is not great, but after sitting for an hour the two clocks were changing in perfect unison. Even at the start they were within 50 ms of each other, so that's still not too much to complain about. I'm certainly confident that it'll be just as accurate or more than the Pi clock I used to have.

The prototype is up and running. It consists of the Pi clock display board with the Pi removed and a SparkFun Pro Micro ESP32-C3 hooked up to it with 5 jumper wires. The wires cary the 3 lines of the SPI interface (MISO is not used), ground and +5. This setup has allowed me to develop the firmware and validate the design (at least as much as possible).

At the moment, the bit still missing is the setup system, which puts the WiFi into AP mode and puts up a web server. That's still TBD. But everything else is working, and that's good enough to move on to dedicated hardware.

The first board has been ordered from OSHPark as well as raw C3-Micro modules from DigiKey and a paste stencil for the modules. Fingers crossed for the first build!