Building the mcHF

Suggested tools, equipment and techniques

Builders of the mcHF should have access to a quality soldering iron. Good temperature control of the soldering station is essential to working with the small SMT based components which make up the mcHF radio. A good pair of ESD safe tweezers should also be available along with a jewelers loupe or desk mounted magnifier.

Soldering the main CPU and other multipin small form factor components can be accomplished using drag soldering techniques. Chris has a great video he put together specifically on soldering the STM32F407 to the mcHF. Andreas DF8OE also has a video - he shows a different method of soldering. The eevblog has an entire series on SMT soldering techniques with the drag solder technique covered in episode #186.

Ordering the parts and compiling a bill of materials (BOM)

The mcHF is composed of two main boards, the RF board and the UI board. Both are available for sale from Chris (M0NKA) from his webpage. He also has complete kits for order so you can avoid having to source all the components yourself and save on shipping.

The original bill of materials (BOM) references parts from the electronics supplier Farnell, primarily supplying to the European part of the world. Builders in the US can use Farnell part numbers with the electronics supplier Newark. Clint (KA7OEI) has also provided a BOM giving part numbers from Mouser, another major US electronics part supplier.

Soldering and Assembly

TBW

Testing

Running Just The UI Board

It is possible to install bootloader and firmware with just the UI board finished. Please note, these instructions do not apply to the mcHF 0.7 hardware (they apply to all hardware featuring the original 30pin connector between UI and RF board). The mcHF uses 3 PCB and has different connectors.

Powering The UI Board

Approach 1: For all board revisions

You will need a reliable source for 5V DC.

• Connect the GND to Pin 30 and 5V to Pin 28 of the 30 pin connector P1.
• Double check you did 30 and 28, and not 1 and 3. Triple check. Remember, if you look on the back pcb side, Pin 30 and 28 are on the right side, if you look from the front side, the pins are left, always assuming the P1 connector is on the top side of the PCB.
• Power on. Check if the connections are stable. Backlight of LCD goes on.

Approach 2: For board revision 0.6

You may populate R43b (or it is populated). This connects the 5V from the Mini-USB to the internal 3.3V regulator and allows to run the board from USB power. That works fine for a standalone UI board test. Remove this resistor before using the UI board and RF board together. Not all PC USB ports will be happy if they receive the 5v from the USB device!

Power Usage

You should see a few milliamps without display, with 2.8" display around 60 to 70mA. These numbers are only valid if no bootloader or firmware is installed and running. In this case you will measure around 240mA.

Installing Bootloader and Firmware

Just follow the instructions for first time bootloader installation given here, then install the firmware using your preferred method. See Firmware Upgrades.

Running The Firmware With Just The UI Board

Please be aware that due to missing power supply the EEPROM and also the audio codec will not be detected, if you just connect 5V. This does not indicate an error, these components get their 3.3V from the RF board. If don't believe this, connect a 3.3V power source to pin 27. Now the Codec and EEPROM should be recognized during startup.