search

stimmer / DueVGA

Arduino Due VGA library
92 stars 30 forks source link

About SMC... (question) #5

Open warpzon opened 11 years ago

warpzon commented 11 years ago

I saw this:"...The colour mode uses DMA to the SMC - static memory controller" If I connect external parallel SRAM like this - http://www.cypress.com/?docID=41968 (which use a SMC), will VGA.lib work? Thanks.

stimmer commented 11 years ago

It's quite difficult to get parallel SRAM working well with a Due anyway because not enough of the SMC bus has been brought out to Arduino pins (a few address and data lines are missing) - I have tried connecting external SRAM and it was more trouble than it was worth, and slow too. Therefore I haven't tried both SRAM and VGA together.

To get colour mode working with SRAM would need at the very least an external buffer on the data bus. The Due can use chip select lines to select between the buffer and the RAM. You would only be able to access the RAM during the vertical blanking period (making the RAM even slower still). I do not think it would be worthwhile.

Monochrome mode might work with SRAM, I don't know for sure. Composite mode definitely won't work as it uses the SMC bus continuously.