Ok, got it all working on the rev1 with the porcupine
Attached is the first image captured.
It's getting a bit late so I'll do some minor cleanup of the rough edges and publish a first prototype for people to try tomorrow. Just something that takes a single frame or so.
In the mean time you can start doing the hw mod to the porcupine that you'll need to try it. (at the moment this is still needed, I hope to lift that requirement).
MOD:
- GPIO_{N,P}7 is turned into a comparator
- GPIO_N7 is fixed to ~ 0.85v. You can do this either with a dedicated lab supply or a simple resistor divider. Personally I used a 1k to VCC_GPIO (2.5v), then 2*1k in parallell (so = 500ohm) to GND.
- GPIO_P7 is connected to GPIO_N8 through a 1k resistor. (value is not critical, but must be large enough to not distort the signal and low enough so that it doesn't take forever to charge the input capacitance of the pin)
I do have something a bit weird with the Xilinx VDMA controller, I configured it for 4 frame buffers (as opposed to 3 in my previous test) and strangely, it's still iterating through only 3 frame buffers ( 1->2->3->1->... ), it just never uses frame buffer 0 ... not sure wtf is going on there.