Dev board mounting

[OllieK]

In my projects, I do use the MCUs (ESP32, STM32, and Teensy) as they are on dev boards. Recently, with the STM32 boards I have preferred models with 4 mounting holes and pins soldered on the top of the boards. The top soldering is preferred because some boards don't have the labeling on the backside and some keys on the front are essential for operations. The connections are done using female Dupont connectors directly to peripherals or through marshalling panels to share the GND and 3V3 lines. For example, to control 8 servos, there are 10 wires from the MCU to a marshalling panel and 24 wires from the marshalling panel for the 8 servos.

With ESP32 dev boards the pins are always on the backside. This implies the following use models

• Insert dev board on a bread board. This is handy during experimental development phase. Although some dev boards are too wide for single bread boards.
• Insert dev board on two sockets on a application specific PCB or a prototyping wiring board.
• Use a 3D printed frame to slide the dev board and use female Dupont connectors to wire those pins that are used in the project.

I am looking your advice based on your own personal experience about the best dev board mounting without bread boards before an application specific PCB is available.

If ESP32 boards would be available without soldered pins or pins soldered on front side then there would be more obvious alternatives.

[WiFive]

You can get devkit c with top female headers also wemos D1 esp32

[OllieK]

I have been using ESP32 products from Wemos and other vendors with creative solutions for mounting and interfacing in many different configurations. At the moment, I need a solution to allow development based on Espressif original development kits to go through the following steps

• Prototyping using a breadboard
• Feasibility demo without breadboard (subject for this post)
• Final product where ESP32 development kit is mounted in a socket on purpose built PCB

Here is my current solution using a 3D printed mounting enclosure for ESP32 Pico-Kit V4. I would like to get your comments how this could be improved.

Here is the development kit


It is inserted in a harness where the pins are on the top side.


The buttons and the power LED will stay on the bottom side.


Marshalling frame will be covering the frontside and keeping the development kit in the harness. The main component in the marshalling frame is the wiring area connecting the MCU pins to the external world. At this phase, all connections are done with female DuPont connectors. The main components in the marshalling panel are the bus bars for GND, 3V3, and 5V.


In the back side of the marshalling frame, you can see the different mounting options with the 7 screw holes.


In the USB connector slot, you can see a bar that is keeping the development kit in place.

[OllieK]

Some additional pictures showing the populated marshalling panel.



In this project, the ESP32 Pico Kit v4.0 is wired for 3 rotary encoders (5 wires), 16x16 LED Matrix (the black and green cable), UART1 (the black, blue, and yellow cable). There are pins to connect the UART0 via the marshalling panel, but in this instance the connection is with the USB cable.

The JTAG pins are left unused to allow testing with the debugger. In this project, the analog signals are not connected to ESP32. Those analog signals are not suited for GPIO connections and in practice only 3 GPIO pins are available for additional functionality.



The short power bar is for 5 V. In this case it is not used because the power is through the USB cable. The long power bar is for the 3V3 peripherals.

[alanesq]

I find using some plastic "pcb mounting pillars" to mount the dev board upside down so it's pins are pointing up is an easy/quick/cheap way to install a project in a case etc.

[OllieK]

@alanesq,

How are you mounting a dev board on the pillars when there are now mounting holes in the Espressif boards? How you are accessing the two buttons on top of a board?

[alanesq]

@alanesq,
How are you mounting a dev board on the pillars when there are now mounting holes in the Espressif boards? How you are accessing the two buttons on top of a board?

Sorry for the confusion - I tend to use the NodeMCU type dev boards which have mounting holes