Hardware (DIY v0.9)

robertfisk edited this page Jul 16, 2018 · 6 revisions

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):

Other hardware:

  • 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:

Connections

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
+5V - EXT2-26 CON1 5V
GND - EXT2-6 CON1 GND
GND2 - EXT1-6 CON4 GND
nTX_OK PA3 EXT2-10 CON3 D0
SPI1_nSS PA4 EXT2-11 CON4 D10
SPI1_SCK PA5 EXT1-18 CON4 D13
SPI1_MISO PA6 EXT1-14 CON4 D12
SPI1_MOSI PA7 EXT1-22 CON4 D11

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.

Next steps

Either set up your JTAG Connection, or load in the latest firmware via DFU.

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