Jianming Liu wrote: > I am writing to query about whether it is possible to use UBB to extend a > SPI ADC (ads8341), because currently I am designing a data collection system > using a SPI ADC ads8341 based on S3C6410.
That should work, yes. One question is what sampling rate you need and how much delay and jitter your samples tolerate. UBB is bit-banged, so your maximum data rate is limited to something like 1 Mbps (or ~30 kSa/s), at 100% CPU utilization. The jitter depends on your trigger. Would you do periodic sampling, have a trigger signal, or would your program decide when it's time on its own ? For anything that uses a timer/external trigger, you need to consider the Ben's interrupt latency. Delay depends on latency plus how quickly you need to retrieve the sample. In the best case, if you have interrupt-driven operation, you'd first retrieve the previous sample and only then start the next acquisition and conversion. That way, you only need one interrupt per sample. > I am considering whether it is > possible use the UBB and JZ47xx instead for this. If "JZ47xx" means that you'll design your own board, then you could use the SPI controller and thus wouldn't have to worry about bit-banging. You'd still have to think about the other timing issues, though (like you would with any other processor). > How to implement the driver for this under Linux, That again depends on your requirements ;-) If they're modest enough, even a user-space implementation might do. Ben+UBB with a user-space driver may also be handy for prototyping. - Werner _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
