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"Misuse" SDIO interface to drive parallel 8bit graphics LCD?

Question asked by bil.til on Mar 29, 2014
Latest reply on Apr 9, 2015 by
I need an LQFP 64 device to shuffle data from an SD card to a small graphics LCD (320x240, mostly small bitmaps).

The LCD I use has a parallel data interface (standard 8bit databus with 11 connection lines: Data line 0-7 CPU, WRX signal CPU, CS signal, Data/Control signal).

All data lines are one-directional CPU -> LCD (I do NOT need to read back data from the LCD).

As the LQFP 64 devices have no FSMC interface, unfortunately I cannot handle the LCD data transfer by DMA.

But there are LQFP 64 devices with SDIO interface. As I can use the SD card in SPI mode, using an SPI interface, I thought about using the SDIO interface in 8-bit mode to shuffle the data to the LCD.

But the SDIO description in the manual is very complex. Hard for me to understand. Has anybody ever tried to use the SDIO interface in 8bit mode to shuffle out parallel data?

I would use the SDIO_CK line as /WR line for the LCD (I checked the signals, as I see it, the SDIO and LCD both use the positive edge of this control line for data write/ read, so this should work).

The LCD needs two additional control lines (/CS and /Control), but these two lines are changed only very seldom - I would just use two normal port pins for this.

PS: I would like to use the STM32F401RC (or possibly also STM32F103RC or STM32L100RC).