|Would somebody who has an 8MB Juicebox with a JTAG connection please check what the base address of the LCD screen is when running the built-in picture viewer? That's set by the LCDSADDR1 register at 0x01F00008, which has a value of 0x160F8F80 in the picture viewer on a 2MB box (indicating an address of 0x0C1F1F00).|
I've finally found some time to try the idea of making specially-formatted pictures executable, by connecting a microcontroller to the JTAG pins that will set up the ARM's breakpoint units appropriately. It looks like this is going to work just fine, with one slight modification: the picture viewer copies image data to the screen in reverse order, so the trigger words will have to be at the top of the image rather than the bottom. However, my code currently assumes that the screen is at a fixed address, and it would be considerable work to change that - it does not currently have to do ANY memory reads, so I can avoid all the complicated JTAGery needed to implement that. All of my Juiceboxes are 2MB units, so I have no idea if the 8MB ones keep the same screen address, or move it to the top of their memory space.