Initially the intention was to utilise a simple arduino clone pro-micro utilising an ATMEL32u4 microcontroller it would be able to be flashed with the MMJoy utility for ease of use.
However in order to get any decent fidelity sensitivity of analogue inputs, an Analogue to Digital Convertor to increase the bit resolution available.
Whilst investigating this further the STM32 bluepill was discovered & the higher specs of this MCU was very attractive. Further investigation resulted in the discovery of the FreeJoy utility which worked on it.
This resulted in disbanding the MMJoy board & pursuing instead an STM32 solution, during the development of this project, covid-19 impacts to shortages in all industries saw prices of components going all over the place, it was actually cheaper to source complete bluepill boards than trying to aquire STM32 MCU chips as standalone items.
Initial development of the FreeJoy board has therefore been done as a shield for a STM32 bluepill, but the intention is to provide a purpose built board including improved power management circuitry to avoid common issues with bluepills being inadvertantly bricked by newcomers.
STM32 Shield prototype
Having finalised the design for prototype / testing / proof of concept, the boards arrived & appear immaculate.
Some of the SMD components, specifically the Shift Registers are a larger available foot print to allow for easier hand-soldering, through hole components are also all hand soldered.
Now to solder the boards to a usable level & perform the testing.
Shortcomings of the STM32 bluepill
the STM32 is a much better microcontroller, however the readily available & inexpensive bluepill board is somewhat lacking & we have refined the design somewhat to add some sadly lacking safety features in the bluepill which can & often results in bricked boards. (One of our friends destroyed 3 seperate boards in one sitting).
To overcome this we have decided to move away from the shield design board, though that might still be made available if an indicated demand exists, in favour of a custom built board with refined safety features & eliminates the requirement of also purchasing a bluepill board.
These customised purpose built boards will be shipped with the current version of FreeJoy configurator installed ready for use. Configuration files can be accessed by a download & applied, or created & manually customised to personal preference.