I have seen many posts about TFT SPI displays relating MISO problem when touch, SD and display memory read are used togheter. Recently I had this problem and among many possible solutions I found a very inteligent and simple one at: https://www.thebackshed.com/forum/ViewTopic.php?PID=193293#193293:
I do not know how and why it works, but it works !!!
Its possible that SDO idles low when it ought to be tristate, in which case your solution would be much simpler than many of the configurations being tried elsewhere. Then again just putting a resistor in series with MISO might be enough.
IMO the proper solution would be to add a tristate buffer, "125" or equivalent depending on details of your project, 74HC125 in DIP for a 3.3V plugblock project or some sort of 5 pin SMT part for a custom PCB. This is one way of dealing with SPI devices that have conflicting outputs.
Then again if the resistor and diode work OK you might leave it at that.
Also FWIW I might have misunderstood the problem, reading about it elsewhere someone described how one of the circuits had a buffer IC on its SPI pins, and it was the buffer IC that was hardwired to be always enabled, meaning the cause was the design of the module and not some kind of IC design error.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.
