It's difficult to find a read-to-use 4.3"-5" tablet/photoframe/panel PC/others at low-cost (50USD) for quantity (1k-5kpcs) that is hackable with a custom firmware/software for my application that requires just the display and a RS485 two-wires ports.
I tried to contact some Chinese photo frames manufacturers, but they aren't available to let me install a new firmware and it's diffult to find a UART port.
So I'm thinking to design the product myself, starting with choosing the display. Could someone suggest a good manufacturer of TFT 4.3"-5" displays with a low price?
I started with the idea of using Android, but even that choice isn't simple. So I'm thinking to use a different UI framework, even if it doesn't support multi-touch or fast movement. The target will be a product to mount to the wall, similar to a stand-alone GPS navigator (like this one buy.garmin.com/en-GB/GB/on-the-road/in-car-sat-navs/latest-range/nuvi-55/prod139770.html).