[Noisebridge-discuss] Big LED Screen - potential upgrade?

[d p chang]

nils at shkoo.com writes:

> The DMA would run between the RAM and be the SPI controller within the
> ARM chip.

ok. i think the ti part is the only one mentioned thus far that does this.

>> unless i missed something else in the pictures (thanks for that) two spi
>> on an arm isn't going to replace two boarduinos since you have to change
>> the spi chipselect for the halves. spi seems fast enough though
>
> The halves don't actually talk full SPI; they just have a data line, a
> clock line, and a strobe/latch line.

right, but if usually you have shared lines mosi/miso lines so someone
has to do some chip select toggling.

a quick look at the ti datasheet makes me think that the dma goes
through the regular control registers. this means that even though the
lines are separate, it looks as if transfers are serialized. it does
mean that you don't have to write 'ready' polling logic though.

>> (although maybe not for nice refresh).
>
> I think you misunderstand. The refresh speed is fixed at about 500Hz.

ok. i was thinking that this was actually a function of your input data
rate. ie, you could get faster (to a limit) panel refresh by writing out faster.

\p
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