Need help in connecting RA8875, sd card module, and USB host shield

I am using Arduino Mega 2560 and I need to connect RA8875 and sd card module but since I am using an RA8875 I need to use a tri state buffer I have the connection attached below. The USB host shield is using ICSP and the RA8875 and sd card are using SPI, I have no idea if I should include the USB shield to tri state buffer or I can just connect it directly to the arduino. I have attached the image of my USB host below too. Thank you in advance :slight_smile: :slight_smile:


ICSP and SPI are the same thing, essentially, with MISO and MOSI on both. ICSP also has reset and power, while SPI has some others as well. This means that you will probably need some sort of select pin for each RA.

I am not exactly sure what you mean by using the USB as a buffer, but as far as I know, all the graphics buffers go either in Atmel SRAM or some other special buffer inside the driver. The USB driver, unless you program it to do something, would just sit there doing nothing.

Otherwise, this sounds like a neat project! You could probably do some kind of virtual reality if you had an accelerometer.

Hope this helps!

I believe that the teensy allows for setting up a second spi bus, which would allow you to connect the teensy to the ra8875 and USB host without tristating the mosi line.

My personal opinion though is the the cold tears displays with ssd1963 and graham lawrences library is a far more superior option... including the ability to easily upload images and icons to the displays font ic chip w/o the need for a sd card... it's also faster.

The only downside is you need something like an Arduino Due or mega since the teensy doesn't have enough I/O for parallel driving of the display.

Sir Maximus I have to tristate the mosi line because of the RA8875, I try connecting the USB host shield alone in the Arduino mega using wires and I connected the USB host shield icsp’s mosi, sck, and miso to the spi but it didnt work sir. Btw here is the library I am using for the USB host GitHub - felis/USB_Host_Shield_2.0: Revision 2.0 of USB Host Library for Arduino.. Thank you for the reply :slight_smile:

Sir deathstar, I am using mega 2560 sir and the ssd1963 is not available here in Philippines sir if I order that on US we will be delayed and we already bought two ra8875 :( thank you for your reply sir