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10 years, 6 months ago.
am having trouble displaying image from local flash memory.
Code worked straight away with a lcd (same as the banggood screen). Having trouble with displaying image from local flash memory. Works fine from sd card though.
Also, is there info on speeding up the update rate of the screen. Is it simply an SPI speed issue? I heard of using DMA (is that direct memory access?). Is there a good reference on how it might be applied to this problem.
Thanks for any help. Appreciate the work on the screen library.
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1 Answer
10 years, 6 months ago.
I would assume is probably mainly a limitation of the mbed SPI lib. Since it first writes, and then reads back, it needs to wait until it is completely done before the spi write function can return. At high speeds this gives a significant overhead. Both DMA or another SPI lib can be faster (BurstSPI for example), but contrary to just SPI that isn't supported on all mbed devices (it is on your LPC1768).
For why it doesn't work via LocalFileSystem (I assume you mean that one) I don't know, you will need to give more info.
Thanks for the reply. I will try to mod the display library and see what happens with another spi lib such as burst spi. I mean the local file system (the one that appears on the pc file explorer). I left the LocalFileSystem local("local"); command out. I thought it was included in the library. Works fine now. Thanks for the help. Will report back when I have tried faster spi.
posted by 25 May 2014