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WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944
Posted: 04:04am 21 Nov 2015
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Will be trying this when next at home with a new TFT. The current TFT has the SD socket removed (due to space constraints within the enclosure).
Note: If no SD card is in the socket then all is ok. BUT then if the SD is inserted, it will fail unless I perform an SD function first. It is as if the SD card has to be 'initialised' first, otherwise the issue happens whenever power is first applied.
I have tried many different SD cards from branded types, to cheap ones. The only common factor here is they are all uSD cards in an full-size SD adapter. Using 2Gb and 8Gb in terms of capacity.
I did play with different CPU speeds along the way, but the issue still remained. I can't remember if the 'time before failure' was different for different CPU speeds though so will test this again.
I have changed from SDCARD 6,7,8 to SDCARD 6 to eliminate anything to do with Card Detect, and Write Protect.
Google implies that there is an initialisation required before accessing an SD card. If true, then when does the MM firmware do this? I assume not at power up because an SD card may not initially be inserted. Does it possibly do this every time an access occurs? Remember that everything works 100% IF I do an SD access first . Surely a socket can't cause this issue??
Regarding a circuit diagram, take the Explore 64 circuit but substitute the 64 pinner with a 100pinner, add an external full size SD socket (connected to the correct pins!) (using SDCARD 6,7,8). Also add a ILI9341 with touch to the necessary pins (TOUCH 48, 47; LCDPANEL ILI9341,L, 49,50,52). Yes I do have other modules and hardware on other pins currently; but these have been totally removed with no change to the issue.
Once I have a second unit built up, I should be able to say whether I believe it is a hardware, software, TFT or SD card issue.