Hi, On Fri, May 02, 2014 at 04:54:31AM -0400, Berk Akinci wrote:
> 1) Is there enough interest in using RaspberryPi as the whole > debugger? (no host/USB dongle necessary.) Well, apparently some people are using that, but I've no idea how many. I still haven't seen any nice buffer board (like the one I was going to build myself as described in that gitorious project). > 2) Is this even a problem? Do people who use the RaspberryPi feel > GPIO bit banging is too slow or am I imagining a non-issue? Well, 4MHz seems to be enough for most practical purposes. And when it's not one can easily buy an FT232H breakout board [1] ($15.3 from Digikey, and don't forget to put ~47 Ohms series resistors on every signal line) and connect it to RPi's high-speed USB port. Current way bcm2835gpio bitbanging is implemented is already quite fast, as close to the hardware as it can get (assembly commands that write to hardware mapped GPIO control registers): it's using /dev/mem interface which can be easily configured to allow non-root access. A possible way to speed it up a bit would be to rewrite it using minidriver API or to at least inline the read/write functions in the generic bitbang framework. Not that I feel there's much need in that. > 3) The BCM2835 SPI controller appears to be flexible enough to use > as a JTAG master. The current SPI driver couldn’t accommodate JTAG. As already noted by the others, you also need control over TMS so I doubt hardware SPI would help here. Talking about SWD, I already have it working both with external buffer configurations and with direct connection to the SWDIO pin (i.e. with direction switching). Upstreaming this work requires cleaning up and streamlining the internal SWD API first but it's already usable with patches from Gerrit. [1] http://www.digikey.com/product-detail/en/UM232H-B-WE/768-1161-ND/3770838 -- Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software! mailto:[email protected] ------------------------------------------------------------------------------ "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
