KrisKasprzak
Well-known member
All,
I have a 3.5" TFT display and I need to use the boards SD card, display and touch. Unfortunately I'm running into the inability to use display MISO and the SD card. The SD and the display SPI are shared but the touch is usign the UTOUCH lib and it's spi is on different pins. Normally I can get the 2.8" to fire right up, but the SD will not work if the display is used. Reason I need MISO for the display is so I can use my PrintScreen function to save the display to the SD card. I'm sure the issue is the infamous tri-state buffer problem and my tests confirm based on this page.
https://www.pjrc.com/better-spi-bus-design-in-3-steps/
I can put a buffer say the 74AHC1G125 as cited on the web page, on the display MISO, but do I need to put another buffer on the SD MISO as well?
I have a 3.5" TFT display and I need to use the boards SD card, display and touch. Unfortunately I'm running into the inability to use display MISO and the SD card. The SD and the display SPI are shared but the touch is usign the UTOUCH lib and it's spi is on different pins. Normally I can get the 2.8" to fire right up, but the SD will not work if the display is used. Reason I need MISO for the display is so I can use my PrintScreen function to save the display to the SD card. I'm sure the issue is the infamous tri-state buffer problem and my tests confirm based on this page.
https://www.pjrc.com/better-spi-bus-design-in-3-steps/
I can put a buffer say the 74AHC1G125 as cited on the web page, on the display MISO, but do I need to put another buffer on the SD MISO as well?