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Hardware (DIY v0.9)
While you can order pre-built USG hardware from the online store, the USG has been designed to allow anyone to build their own from readily available development boards.
Build your own USG v0.9
You will first need the following hardware directly from Olimex, or through Digikey (who usually ships quickly):
- 1x STM32-H405 with USB device port: Olimex or Digikey
- 1x STM32-H407 with USB host port: Olimex or Digikey
- 1x 0.1uF through-hole capacitor, ceramic or monolithic type
- 20cm of 1mm diameter tinned copper wire
- Wire cutters
- Soldering iron, solder, and some soldering experience
For firmware development work:
If you don’t want to develop firmware and only want to use the latest firmware image, you will need:
- 1x USB A male to male cable. Check the DFU Firmware Upgrade page for more details.
Your goal is to connect +5V, Gnd, and the SPI1 port of your two Olimex development boards together.
|Signal name||MCU pinout||H405 pinout||H407 pinout|
Here is the same information in pictures:
Position the H405 board (smaller) on top of the H407 board (larger) with the USB connectors facing in opposite directions. Use the 1mm tinned copper wire to link the boards together. When all required connections are in place the wire will provide adequate mechanical support.
The H407 board comes with handy rubber feet, but be aware they require some determined twisting to insert. When you are done you should have something like this:
Bugfix the H405 board
Under heavy use, the H405 board will occasionally glitch out and your USG will crash. To fix this you need to add a 0.1uF filter capacitor to the CPU’s reset line. The easiest way to do so is by soldering it across the pins of the reset button, as below.