From: Dave H. <dhy...@gm...> - 2010-05-22 15:56:55
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Hi Ash, On Sat, May 22, 2010 at 12:40 AM, Ash Charles <ash...@gm...> wrote: > On Fri, May 21, 2010 at 6:40 PM, Dave Hylands <dhy...@gm...> wrote: >> Hi Ash, >> >> On Fri, May 21, 2010 at 5:01 PM, Ash Charles <as...@gu...> wrote: >>> Afternoon, >>> >>> We've looked through the pin-muxing for this board and we propose the >>> following 3 by 8 pin right-angle 0.1"pitch male headers: >>> >>> =====HEADER #1===== >>> PWM0 PWM1 PWM2 PWM3 PWM4 PWM5 PWM6 PWM7 >>> Vbat Vbat Vbat Vbat Vbat Vbat Vbat Vbat >>> GND GND GND GND GND GND GND GND >> >> Hopefully, these will be Vmotor, which is jumpered to Vbat. > To make sure I understand what you meant in your previous post, the > jumper on the Robostix allowed people to use either a battery or a > wall wart to supply power to the board? > For the new board, the 'Vbat' signal (definitely a misnomer on my > part) would be the V+ line taken directly from the power source be it > a wall wart or a battery. I guess by battery you really mean a dedicated 2-pin power connector. >> How will the luminary micro be programmed? Will a JTAG interface be available? > I hadn't included the JTAG interface; I think this requires an > additional four pins which is not impossible but board space would > start to get tight. One option would be putting contact pads for > JTAG...does this seem useful? > The device can be accessed via I2C0, UART0, or SSI0. I just wanted to make sure that you address how the device will be programmed. I see that it does indeed have a ROM based bootloader which can be programmed as you indicated, which somewhat alleviates the need for a JTAG. Although having the JTAG allows a debugger to be used, which I think will be important. If you put the pads somewhere that a 10-pin JTAG mini connector could be used <http://www.luminarymicro.com/products/mdl-ada2.html> This could be a surface mount connector. It looks like its a 2x5 0.050" header (see the schematics and BOM for this eval board: <http://www.luminarymicro.com/index.php?option=com_remository&func=download&id=983&chk=d1a772ed2075b69e938af114b279083b&Itemid=591> >>> Secondly: is the arrangement of pins correct? >>> -- on Header #2, should the UARTS be four pins each (RX, V+, TX, >>> GND) with all three stacked on top of each other? e.g. >>> RX0 5V TX0 GND >>> RX1 5V TX1 GND >>> RX2 5V TX2 GND >> >> The Arduino stuff seems to have standardized on using: >> the same pinout as the FTDI USB-to-logic level serial connectors which is >> >> 1 - GND >> 2 - CTS >> 3 - VCC >> 4 - TXD >> 5 - RXD >> 6 - RTS >> >> <http://www.ftdichip.com/Products/EvaluationKits/TTL-232R-3V3.htm> >> >> On the Arduino, the RTS pin is tied into the reset circuitry so that >> the board can be reset (and serial downloaded to) from the host. >> >> Having the 4 pin layout which is compatible with the robostix also >> makes sense. I just wanted to throw out the Arduino thing since it's >> quite popular. > Thanks for pointing out the Arduino connector; I'd been hunting around > to see if there was such a standard earlier today and hadn't found > anything. > Is there a strong motivation for including the CTS and RTS lines? I > don't recall using them before so I found it hard to justify extra > pins but perhaps this is more a reflection on my inexperience than on > the utility of these pins. Being able to reset the microcontroller through the download interface is nice. It means that the SW can do the reset and send the appropriate bytes with appropriate timings, rather than relying on a particular sequence of events by the user. Although looking at the protocol, it seems pretty easy to just start the host side program and then hit reset on the micro. So I think you could eliminate the extra lines if you need the space. It would be nice, especially in standalone mode to be able to connect up the FTDI chip normally used for the overo console to the micro, perhaps using some switches, or DNI resistors. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |