I’ve been flicking through the datasheet for the screen and apparently its possible to read pixel data back from the screen using command 0x22.
Does anyone know anything about this? Is the hardware even setup to make it possible?
Read Data from DRAM (R22h)
RD [17:0]: 18-bit data read from the DRAM. RAM read data RD [17:0] is transferred via different
data bus in different interface operation. When the ST7775R reads data from the DRAM to the
microcomputer, the first word read immediately after RAM address set is executed is taken in the
internal read-data latch and invalid data is sent to the data bus. Valid data is sent to the data bus
when the ST7775R reads out the second and subsequen t words. When either 8-bit or 16-bit
interface is selected, the LSBs of R and B dot data are not read out.
Here’s an idea! use it for double buffering when using direct pixel modes. Simple draw the gfx to an off screen region then jump to it with hardware scroll then repeat… I wonder if hardware scroll or screen offset or whatever lets you do that.