gaensli / Icebreaker - History

Changed the inline CRESET resestor to 2k2.

We need a lower resistor value so that the FTDI chip can reset the FPGA.
Using a 10k resistor results in a voltage divider and the 1.65v is too
high to assert reset.

Added differential comparator input pin pair groupings.

The symbol in the schematic now shows which pins form diff comparator
input pairs.

Add an FPGA CRESET jumper. Fixes #9

Adding an in line resistor for the CRESET line from FTDI as well as a
jumper that allows access and pulldown of the CRESET line. This allows
us to override the CRESET signal from FTDI and force the FPGA chip to
stay in reset in cases when we need to access the flash and prevent the
FPGA from configuring the FLASH chip. Especially in cases when the FPGA
is using the FLASH after the design is loaded and configures the flash
into QSPI and other higher bit modes.

Added pulldown on the B port ~CTS ftdi line. Closes #10

With this line pulled down we can use minicom even when hardware flow
control is enabled. If this pin is not pulled low and hardware flow
control is used, no data is ever sent out by the FTDI chip. This can
easily happen because minicom has hardware flow control enabled by
default.

I decided to only add the CTS line pulldown to keep the placements under
control.

Use normally closed jumpers. And fix VCCIO2 bypass. Closes #11

These jumpers connect two nets without impacting the schematic net
lists. This is a safer solution and easier to read than having to
remember where the net jumpers have to go and not miss a side path.
These jumpers use a hack of KiCAD where the DRC ignores lines on the
copper layer in footprints. The two pads of the jumper are shorted
within the footprint but they are not from the perspective of the DRC.
While I was already at it I have also replaced / separator with |
separator for multifunction nets. Unfortunately KiCAD reserves the /
separator for its multisheet net naming. This patch should fix the
bypass of the VCCIO0 jumper that was a mistake in the previous versions
of the board.

Initial commit of icebreaker V1.0a hardware.

Work in Progress.