A long while ago I wrote about that I might make a series of boards for easier testing of the open USB stacks. Testing all different version of mcu’s and crystal speeds to make the right #defines and linker maps for the firmwares can be a bit tedious.
OSUS will make life a bit easier by removing most of the parts required on the boards to be tested by moving the other parts to this master board. The test-boards basically only need a decoupling cap two and a 14 pin 0.1″ pin header – that’s it.
On the OSUS master board there’s a Reset button and .a extra button to be used for invoking the bootloader or just for general usage. There are also three status LEDs for simple debugging and a connector to a BusPirate LCD adapter for more involved stuff.
The crystal clock speed can be set in 15 steps between 1.25MHz and 48MHz and is provided to the test-board in both 5 and 3.3 volt versions.
Of course there are a ICSP connector and a USB Mini connector on the board as well. It’s possible to disconnect the USB D+/D- by removing two jumpers.
All of this on a SOB DP5050 -sized board.
I’ll solder up some MCU test-boards for this and give it a spin. I’ll be happy to send a presoldered OSUS Master board for free to those who contribute to the Open Source USB Stacks out there.
After setting the frequency jumpers to 20MHz, plugging in the Pickkit to the right and the USB cable to my laptop to the left I could easily flash it with the JTR USB stack, debug it via the three green staus LEDs and see that it enumerates as a CDC device on the laptop.
Jumpering the oscillator to 16MHz and then change the configwords.h in the code, recompile and flash to test is quick and painless.
For more detail: OSUS – Open source USB Stack test board