There is a number of options you have for display shields for the D1 Mini: there is the nice OLED shield, there is a shield with a single WS1228B neopixel, there is the #D1 Mini Matrix Shield I’m still working on. But there is no high-resolution color display you could just slap on it. This “shield” doesn’t really deserve the name, it’s just a simple breakout board that connects the ST7735 display module with the SPI pins of the D1 Mini, and adds a trim pot for brightness control.
To save some pins, the CS pin is hardwired to GND, and the A0 pin is connected to MISO. That means you can’t connect other SPI devices while this is in, but that’s a rare enough case for me to care. It uses four GPIOs total, from GPIO12 to GPIO15. The backlight is connected to the 5V supply (to not strain the on-board 3V3 regulator) through a trim pot, so you can adjust brightness.
I used alternating holes for the module’s header, so that with some luck you should be able to plug in the module directly, without soldering a female pin header there — that should also save some space.
Modems have been around for longer than the web, and before we had Facebook we had the BBS scene. Somewhat surprisingly, people are still hosting BBSes, but have fun finding a landline these days. [Blake Patterson] is one of the leading aficionados of retocomputers, and recently he took it upon himself to review an interesting new…
From debug messages to the fundamental ‘hello world’, serial communication does it all over three little wires. Now imagine being able to cut the cord to your next microcontroller project and use your phone as a VT100 terminal. This was the premise of [Ondřej Hruška]’s Wireless Terminal Project where he took an ESP8266 and added an in-browser terminal emulator which can be accessed…
Castellations are small plated edges, typically used for making circuit boards into small PCB modules. These are often seen on wireless modules, such as the ESP8266-12E.
While we don’t offer full support for castellations, they can be fabricated if you don’t mind a few minutes of rework and verification of the PCBs.
It’s helpful to include a fallback hole near the edge. The ESP8266-12E boards, are a great example here. The extra via allows easy connecting of wires for rework, and makes it easy to salvage a module if the fabricated PCB doesn’t turn out perfectly.
Indicating in the design file
Castellations are simple to call out in most design tools. Simply include a via on the PCB, so the board outline goes through it.
However, due to our panelization process, the castellated vias must be indicated with round pads for copper and stop mask. The pads must also not extend more than 40 mil from the board edge. Square pads or pads that extend far beyond the edge will be trimmed, and the via will not be plated.
It’s also helpful to use a 10 mil wide line for the board outline. With our milling tolerance of 5 mil, this provides a good visual indicator of where the physical board edge might be. The fabricated edge can be anywhere within that line. This is very helpful for fine-pitch castellations with smaller holes.
Rectangular castellations can be made by using vias with round pads as noted above, and adding overlapping rectangular SMD pads. Since these pads are inside the board outline, they will not be trimmed, and will provide additional area for soldering (see below for example).
Cleaning up the final boards
We make a best-effort to minimize support tabs on castellated edges, but it sometimes happens. In these cases, you’ll need to file the tab off of your edge.
Additionally, the via plating may not be fully removed during the milling process. In some cases it’s smashed next to the edge, where it can cause unwanted connectivity between vias. In others, it’s smashed inside the via, where it will prevent good solder flow. A fine point file or hobby knife will help remove excess plating.
Upcycles D1 Mini Wemos board to create a USB connected ESP8266 Pogo pin jig
This is a board designed to take a WeMos D1 Mini board(with the ESP module removed) and use it as a USB interface with built-in reset/flash functionality for bare ESP8266 modules similar to the ESP-12 units.