On 02.05.2014 11:25, [email protected] wrote: >> 3) The BCM2835 SPI controller appears to be flexible enough to use as >> a JTAG master. The current SPI driver couldn’t accommodate JTAG. >> If I go about writing a new driver on the Pi, how should the >> interface >> look to the application (OOCD specifically). Do you have other JTAG >> interface that you feel is such a good fit, I could use as an >> example? >> (Or your dream JTAG interface…) > I do not not much about the hardware limits of the SPI controller > inside the Pi but: > > My first thought is that it probably would be nice to be able to > transfer any numbers of bit, and not be bound to it being dividable by > 8. > > For SWD, TX and RX can probably be bound together, but the TX needs to > be able to tri-state unless a an external buffer is used. Having an external buffer is a good idea, anyway.
If it works without external logic for simple 3.3V-only-cases, that is great, but some protection for the PI's ports is nice to have - and for sub-3.3V targets, it is required anyway. cu Michael ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ OpenOCD-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/openocd-devel
