Sun Feb 27 14:29:02 EST 2011


The Microchip 23A256 256kbit SPI SRAM[1] arrived.  I wonder if I can
use this to implement a TV/VGA frame buffer.  Does it support
continuous bit stream to dump out serial bits without any gaps?  If
so, readout can be used to draw scan lines, and the dead time can be
used to upload data.  In the datasheet[2] it is mentions that it
supports sequential operation, so giving it a proper clock will just
dump out all the bits.  The remaining problem is then to detach the
RAM SPI data output from the frame buffer output when we're updating.
This can be done using a simple resistor connected to a PIC pin that's
kept floating when the RAM is supposed to drive the output, and tied
high or low when it is not.

Other applications are 1 bit sample playback.

[1] http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en539040
[2] http://ww1.microchip.com/downloads/en/DeviceDoc/22100E.pdf