carl0s
Member
Hi!
I'm well out of my depth here, but I'll have a go..
I have on order, a 3.4" 800x800 MIPI round display. I've spent the last week or so getting my head around stuff, realising that microcontrollers and MIPI don't go hand in hand.
At 16bpp, 800x800 would be 1.2 megabytes of pixel data I think ? So I need a framebuffer, or a controller with a framebuffer.
The screen has an ILI9981c controller which has no GRAM or framebuffer (one and the same? does GRAM mean graphics ram?).
I was thinking of using an SSD2828 to convert from RGB to MIPI. It has the requisite 3 MIPI DSI lanes. I originally thought I'd try a different MCU such as the stm32L4r9 or stm32f469/f479 with their inbuilt gfx engine and MIPI DSI, but they are only 2 lane DSI :-/
I think the SSD2828 because it has no framebuffer though, would require a framebuffer constructing out of MCU memory, and, well, I think some sort of hardware graphics helper will help a lot.
So I am thinking (and have ordered some bits for), a module consisting of:
MCU SPI connection input -> RA8876 graphics / display controller + external 512MBit SDRAM -> SSD2828 which will convert RGB output from RA8876 to MIPI, which will then go into the ILI9981c that is inside the display.
I am feeling brave with the el-cheapo hot air soldering iron, and I hear you can get PCBs made cheap.
What do you think? Dreaming?
The screens are on order anyway, as are 0.4mm pitch QFP breakouts, and LCD FPC breakouts, etc.
RA8876: http://www.raio.com.tw/data_raio/Datasheet/RA887677/RA8876_Brief_DS_V11_Eng.pdf
SSD2828: https://datasheet.lcsc.com/szlcsc/SSD2828QN4_C48596.pdf
ILI9981c: http://en.startek-lcd.com/res/starteklcden/pdres/201706/20170617115241070.pdf
I'm well out of my depth here, but I'll have a go..
I have on order, a 3.4" 800x800 MIPI round display. I've spent the last week or so getting my head around stuff, realising that microcontrollers and MIPI don't go hand in hand.
At 16bpp, 800x800 would be 1.2 megabytes of pixel data I think ? So I need a framebuffer, or a controller with a framebuffer.
The screen has an ILI9981c controller which has no GRAM or framebuffer (one and the same? does GRAM mean graphics ram?).
I was thinking of using an SSD2828 to convert from RGB to MIPI. It has the requisite 3 MIPI DSI lanes. I originally thought I'd try a different MCU such as the stm32L4r9 or stm32f469/f479 with their inbuilt gfx engine and MIPI DSI, but they are only 2 lane DSI :-/
I think the SSD2828 because it has no framebuffer though, would require a framebuffer constructing out of MCU memory, and, well, I think some sort of hardware graphics helper will help a lot.
So I am thinking (and have ordered some bits for), a module consisting of:
MCU SPI connection input -> RA8876 graphics / display controller + external 512MBit SDRAM -> SSD2828 which will convert RGB output from RA8876 to MIPI, which will then go into the ILI9981c that is inside the display.
I am feeling brave with the el-cheapo hot air soldering iron, and I hear you can get PCBs made cheap.
What do you think? Dreaming?
The screens are on order anyway, as are 0.4mm pitch QFP breakouts, and LCD FPC breakouts, etc.
RA8876: http://www.raio.com.tw/data_raio/Datasheet/RA887677/RA8876_Brief_DS_V11_Eng.pdf
SSD2828: https://datasheet.lcsc.com/szlcsc/SSD2828QN4_C48596.pdf
ILI9981c: http://en.startek-lcd.com/res/starteklcden/pdres/201706/20170617115241070.pdf