i'm not that new to arduino, but i'm new to this chapter of the forum on display's
for a project, i'm eyeballing to a 5" (or 7") TFT display from buydisplay (eastrising)
I have a RA8875 480x272 bare module that I use with 3.3V SPI.
If you are familiar with the Demo that comes with my MCUFRIEND_kbv library, you would be gobsmacked by the sheer speed of the RA8875. e.g. the full set of Adafruit tests take about 0.65 seconds with a Uno.
I have just ordered (yesterday) a RA8875 800x480 with Arduino shield. This screen is about 3x bigger so I would expect 2.0 secs.
This is far faster than a SSD1963 running on a Due native 16-bit parallel adapter shield.
Note that there is hardware acceleration for every graphics and text operation. Hence the speed. Hence the SPI speed is unimportant.
Things like transferring data from a SD card are no faster than anything else.
However if you pre-burn a Flash chip, the RA8875 will transfer data with DMA.
This is only practical for a production item. You can't program the Flash in situ.
I cannot see any point in the SSD1963 shield. It will be the same performance as a Mega Adapter shield.
Likewise the ILI9488 480x320 or ILI9341 320x240 display with shield. You might just as well buy a purpose built one-piece display shield.
OTOH, apart from the SSD1963, everything else can run with SPI. Or parallel if you solder a $1 worth of chips.
David.
p.s. the RA8875 is very fast. It has a few quirks. I am just learning.
david_prentice:
You can't program the Flash in situ.
Says who? I can
David,
I know you will understand this, and sorry about hijacking the thread! But ... my Arduino based 'Flash_Multifunction' sketch has evolved quite significantly since inception, to the extent I can now run a Windows program which can remotely instigate a font dump to TFT from Font IC, request screen dump data and save it as a PNG on the PC. My current collection of fonts runs to 1120 which equates to 14 font families in 10 sizes as proportional and mono-spaced flavours as standard or alternative sizes. I have a batch file which runs automatically and reprograms the Font IC 8 times during the course of producing the 1120 screen shots representing all versions of the fonts I currently offer. I am REALLY proud of this! You didn't respond to my email so maybe you are not interested... But I will continue development regardless of lack of general interest. You might like to look here, all thanks to readGRAM!!
You might want to try the high speed usb patch, and updated Flash_Multifunction if you have not already done so... Next thing is overclocking..... many exciting developments in the pipeline!
My 480x272 screen takes about 90ms to render the whole screen from the Flash chip.
So I would expect 270ms for an 800x480 screen. (I actually rendered the Font chip)
Copying an image from AVR memory takes a long time over the public SPI bus.
The Flash (and Font) chip are on a private SPI bus. The WP pin is wired true on the Flash chip.
The RA8875 is designed to read from its private SPI bus. (which it can do with DMA)
I will do some experiments. I might be able to put the RA8875 in Reset. Then grab the bus manually. I have already lifted the WP pin.
Ra8875 also has a bug in its spi bus which means you've got to use an external buffer to tristate the miso pin or forget about using other spi devices (sd card, for example).
On the buy display boards, you cannot use the onboard sd card reader due to this bug.
OTOH, if it can be controlled by the RA8875 e.g. write, erase, read ID, ...
then it would be worth tying /WP high.
EastRising would not be the first company that needs mods on a pcb.
Soldering only 7 pins to the pcb and 1 pin bent upwards.
Of course, this is not attractive.
Mind you, the RA8875 performance is so impressive in many ways that it is worth the effort.
But only if I can find an undocumented feature that can send 'other' commands than 0x03 from the controller.
Yes, I have to investigate the MISO behaviour. Will 3-wire mode disconnect it?
