On 10/02/2012 3:55 AM, David Riley wrote: > Hello all, > > I'm building a board with an FT4232 on board to support UART access of > various devices and reprogramming of the onboard ARM. I'd like to use SWD > instead of JTAG for the ARM if possible, but I'm having a hard time finding > documentation on how to hook up the 4232 so that it will be supported by > OpenOCD. > > The best guess I have comes from the KT-Link manual, which shows a > multiplexer connecting the TDI/TDO pins to the TMS output (which is the > standard pin used to connect SWDIO in a multilingual system). Another schematic you can look at is TI ICDI, it'll do swd also (based on FT2232). Once swd is up and running it'll surely be supported. It'll give you a full schematic (in the user manual any dev kit that includes it) rather than just the basic outline you get of a kt-link, but yeah the kt-link will be supported first certainly.
> If I were to assume that I'll never use JTAG (I'm trying to keep the BOM > for the board down, but I guess a MUX or a DPDT switch wouldn't break the > bank), would it be reasonable to just connect the TDI/TDO pins together > through resistors (a la converting MOSI/MISO to a bidirectional SPI line)? I think the resisters should definitely work, the ft4232 should have no problem driving the swd line directly, so long as it's not too far track-wise to the main chip. Depending on how tight you are for board space I'd wire up to all the jtag lines as well (with jumpers to enable), and put space for the full buffer system, but have the resistors/jumpers in as well so you can place/not place parts as needed later on. At least on a first prototype that'd definitely be worth doing, and you can scrap the space for buffers later if you need to on a future build? This would allow you to use jtag initially while waiting for swd support to catch up in software, so long as your processor has jtag at all. > > Or is there a more efficient way of connecting these up? I haven't delved > into the guts of the MPSSE code in the FTDI code, so I don't know if there's > a more efficient "direct" connection for this. > > Also, since this is a small, internal project and we're not about to acquire > USB VIDs: if I leave the 4232 in "generic" mode (i.e. using FTDI's VID/PID), > will I be able to "claim" the JTAG/SWD port dynamically with OpenOCD? I know > my Olimex pod has an entry in FTDI's OS X driver that claims the serial port > but leaves the JTAG port open, and I'm wondering if I'll run into the same > problem. I used the amontec layout for one of my integrated debuggers (internal design only) and I naughtily used an amontec vid/pid as well to make openocd use it easily. I should figure out myself if I can use openocd in amontec layout with generic vid pid though, becuase sometimes my ft2232 isn't reading the eeprom chip on bootup correctly.... I've given that board a pretty hard time during development. > > Many thanks in advance, > > - Dave > ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ OpenOCD-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/openocd-devel
