RA8875 Driver Board For 40-pin TFT Touch Displays – 800×480 Max

Have you gazed longingly at large TFT displays – you know what I’m talking about here, 4″, 5″ or 7″ TFTs with up to 800×480 pixels. Then you look at your Arduino. You love your Arduino (you really do!) but there’s no way it can control a display like that, one that requires 60Hz refresh and 4 MHz pixel clocking. Heck, it doesn’t even have enough pins. I suppose you could move to ARM core processors with TTL display drivers built in but you’ve already got all these shields working and anyways you like small micros you’ve got.

What if I told you there was a driver chip that could fulfill those longings? A chip that can control up 800×480 displays, and heck, a resistive touchscreen as well. All you need to give up is 5 or so SPI pins. Would you even believe me? Well, sit down because this product may shock you.

The RA8875 is a powerful TFT driver chip. It is a perfect match for any chip that wants to draw on a big TFT screen but doesn’t quite have the oomph (whether it be hardware or speed). Inside is 768KB of RAM, so it can buffer the display (and depending on the screen size also have double overlaying). The interface is SPI with a very basic register read/write method of communication (no strange and convoluted packets). The chip has a range of hardware-accelerated shapes such as lines, rectangles, triangles, ellipses, built in and round-rects. There is also a built in English/European font set (see the datasheet section 7-4-1 for the font table) This makes it possible to draw fast even over SPI.

The RA8875 can also handle standard 4-wire resistive touchscreens over the same SPI interface to save you pins. There’s an IRQ pin that you can use to help manage touch interrupts. The touchscreen handler isn’t the most precise driver we’ve used, so we broke out the X/Y pins so 11:54)

Please note: the bottom of the RA8875 PCB has some pads that you can solder which gives extra power to the backlight (if you feel the backlight isn’t bright enough).

Technical Details