This adds connections from the A2 - A5 inputs on the Arty A7 to the
XADC module in the Artix-7 plus a way for software to access the XADC
via its DRP port, and a status register to tell software when
conversion sequences are done.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds an interface for an Arduino-compatible LCD touchscreen. The
screen module plugs directly on to the Arduino/chipKit shield
connector on the Arty A7. Unfortunately, the slightly strange way the
resistive touchscreen is brought out (connected to the D0, D1, RS and
CS pins) combined with the 200 ohm protection resisters on the Arty
board mean that some hardware hacks to the module are necessary. I
rewired mine so that D0 and D1 are on the A4 and A5 pins and the reset
is where D0 was (shield I/O 8).
This interface is suitable for boards with a HX8347 driver chip. The
timing may not be quite suitable for other driver chips.
The interface is a byte which can be read and written at 0xc8050000,
containing an index register, and a 1-8 byte data register at
0xc8050008. Reading at offsets 1 to 7 from those addresses yields the
same value as at offset 0. Writing 64 bits to the data register
writes the bytes at offset 1, 0, 3, 2, 5, 4, 7, 6 in that order to the
driver chip. This allows pixel data to be transferred using 64-bit
writes, ending up in the frame buffer in the expected order (for
16-bit pixels, the driver chip expects MS byte then LS byte). 32-bit
writes do 1, 0, 3, 2, and 16-bit writes do 1, 0.
The touchscreen support so far is a 1-byte register containing bits to
set RS, D0, D1 and CS high or low or make them tri-state. There is
nothing to do analog conversions of the signal levels at this stage.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras