Hi all,
Here's my effort so far.....
4.58", 320x960 TFT LCD.
STM32 Blue Pill (STM32F103C8T6)
LT7680A-R TFT Graphics Controller.
It's been quite a journey to get to where this is right now, but today I got text rendering working on the display.......over the moon and over the technical hurdle, should be easy from now!
I decided to use the STM32 Blue Pill as I am experienced with them and they are easily integrated for somebody wanting to build up my version. However, out of the box and on their own they are NOT up to the task. Not enough I/O for one.
I picked the LT7680A-R controller because of it's size, it's narrower than the LCD and will mean it's easy to mount on the back and it of course took the heavy lifting away from the Blue Pill, just simple SPI comms with the LT7680A-R is required.
However, the way the LT7680A-r works is that you still need to communicate directly (via the pcb) to the LCD's ST7701S COG, albeit only once at startup to configure things.
In total I needed 3 SPI ports, the R6581T gets one, the LT7680A-R and............oh, the Blue Pill only has 2 SPI ports!
So, I bit banged a 3rd, the 3-wire interface to the ST7701S. It's only used once at boot so no worries.
Actually, I nearly went with the STM32 Black Pill (I still might) as it has 3 SPI ports, but we'll see.
I plan to design a Pcb thats the same dimensions as the LCD and mount everything on it. The green Pcb in the photo is just a temporary one used for dev.
Software is developed in Visual Studio/Visual GDB, and through the STLINKV3 it's got pretty good debugging, I can live watch variables etc.
By far the biggest problem was the LT7680A-R, the datasheet/manual and the supporting App notes are quite extensive. I had to sync the settings such as the back porch stuff and of course they are in different units and needed tweaked even after that. Also, having to set up the LCD PCLK, VSYNC, HSYNC settings...........having never driven a TFT direct before it was quite a learning experience.
The LCD pic below is just the first font I picked, plan is to have the nicest, smoothest font I think.
Thats all for now.
Ian.