Help needed getting STM32-Eval board LCD into 18bit mode over spi

[stm321]

Posted on June 05, 2008 at 19:31

Help needed getting STM32-Eval board LCD into 18bit mode over spi

[stm321]

Posted on May 17, 2011 at 12:35

The docs with the evaluation board say the M524B LCD has an ILI9320 controller.

Using the datasheet and demo application code I have not been able to get the device to switch into 3 bytes per pixel transfer mode through the SPI interface. I have tried writing to R03 0xCxxx or 0xC2xx config words but tests show that it is still only expecting 2 bytes per pixel (16bit mode). The datasheet implies that you only have to set bit TRI and DFM to one to do this. There is a mismatch in the d/sheet as in one place it states that DFM is two bits but the register definition only shows on bit. If you have figured this out please pass on your superior knowledge. Cheers.

[jj]

Posted on May 17, 2011 at 12:35

Don't know about superior knowledge...

straight from ILI9320 spec: TRI When TRI = “1�, data are transferred to the internal RAM in ''8-bit x 3 transfers mode'' via the ''8-bit interface.'' *** imho - this means PARALLEL, 8 bit transfer! (ratz) however - spec continues (& raises hopes): It is also possible to send data via the 16-bit interface or SPI in the transfer mode that realizes display in 262k colors in combination with DFM bits *** THIS appears to be what you/others are after! So - how to do it? (truth in advertising - my firm has NOT yet tried this) On the right edge of the flex circuit of the Lcd you'll see JP1-JP4. Now these jumpers equate to IM0-IM3 - described on pg 3 of the 36 pg. Lcd spec. The factory default: IM3=0, IM2=1, IM1=0, IM0=0 corresponds to SPI *** 16 bit *** interface! (note: IM3 relates to JP4, IM2 to JP3 - to keep us further on our toes) To get into 18 bit mode you need: IM3=1, IM2=0, IM1=1, IM0=0. The spec (imho) is not adequate here in defining IF you CAN achieve 18 bit color (3 transfers) by so doing. All of my review of the SPI diagrams reveal ''only'' 2 transfers (16 bit color) - exactly as you have reported. Perhaps you want to r/r the flex circuit jumpers - experiment - and report back to our forum. I must state that I don't see substantial gain in 18 versus 16 bit color. Hope this helps - good luck.

[jj]

Posted on May 17, 2011 at 12:35

stm32

Are you still pursuing 18 bit color?