From: Gordon K. <go...@gu...> - 2005-02-25 15:54:20
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> Hi,<br> <br> I have tried to take all points into consideration and I would like to hold a new design out for further comment. Here: <a class="moz-txt-link-freetext" href="http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=+Robostix">http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=+Robostix</a><br> <ol> <li>I revised the board to use 2mm spacing on all connectors except the servos, uarts, and I2C. Servos seem to universally use the 0.100" spacing.</li> <li>Can I do 0.100" board that's bigger? Yes-- but is 2.00mm pitch OK (versus 2.54mm == 0.100")?</li> <li>I have also borought out power and ground adjacent to all signals: AGND and AVCC to the ADC pins, VCC5 to the UARTs, V_MOTOR and GND to the servos, and V_BATT to the remaining power pins. I would especially appreciate comment on this as it pertains to the overall power strategy; namely, that V_BATT is provided as a power source bus, reasonably regulated at 5V and providing 1A total. Vcc is 3.3 and is intended for this board only; Vcc5 similarly.</li> <li>The UART arrangement is a little different, but allows power and ground as well as the chance to jumper level-shifted PXA signals to the ATmega128.</li> <li>The SPI bus is strictly between the PXA and ATmega128 for communication and boot-download at this point, with the PXA as the master and thus limited to 3.6864MHz per the intel docs.<br> </li> </ol> Have I missed anything major?<br> <br> Finally, you may note that there are still a few lines open. Any selections? Oh, and I think that I will bring out the PA onto unpopulated pads on the reverse side.<br> <br> Thanks for the comments,<br> <br> Gordon<br> </body> </html> |
From: Dave H. <dhy...@gm...> - 2005-02-25 16:25:16
|
I had to use this link instead: http://www.gumstix.org/tikiwiki/tiki-index.php?page=+Robostix On Fri, 25 Feb 2005 07:54:19 -0800, Gordon Kruberg <go...@gu...> wrote: > Hi, > > I have tried to take all points into consideration and I would like to hold > a new design out for further comment. Here: > http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=+Robostix -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Jay P. <jay...@gm...> - 2005-02-25 19:34:29
|
I'm a little late to the conversation, so maybe this is covered already, but I couldn't find it on the schematics. Are you going to bring out I2C to a header of some sort? And include pull up resistors, preferably to a 5V power source? (Either the I2C on the AVR or the XScale would be fine by me....but 5v would mean that its the AVRs I2C.) Very exciting board idea... would solve a couple problems for me that I'm using multiple boards to accomplish right now. On Fri, 25 Feb 2005 08:25:07 -0800, Dave Hylands <dhy...@gm...> wrote: > I had to use this link instead: > http://www.gumstix.org/tikiwiki/tiki-index.php?page=+Robostix > > > On Fri, 25 Feb 2005 07:54:19 -0800, Gordon Kruberg <go...@gu...> wrote: > > Hi, > > > > I have tried to take all points into consideration and I would like to hold > > a new design out for further comment. Here: > > http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=+Robostix > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------- > SF email is sponsored by - The IT Product Guide > Read honest & candid reviews on hundreds of IT Products from real users. > Discover which products truly live up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Gordon K. <go...@gu...> - 2005-02-25 20:37:17
|
Jay Prince wrote: >I'm a little late to the conversation, so maybe this is covered >already, but I couldn't find it on the schematics. Are you going to >bring out I2C to a header of some sort? And include pull up >resistors, preferably to a 5V power source? (Either the I2C on the >AVR or the XScale would be fine by me....but 5v would mean that its >the AVRs I2C.) > >Very exciting board idea... would solve a couple problems for me that >I'm using multiple boards to accomplish right now. > > > > I2C is included with pull-ups to 5V. Gordon |
From: Dave H. <dhy...@gm...> - 2005-02-25 21:00:53
|
Hi Gordon, On Fri, 25 Feb 2005 07:54:19 -0800, Gordon Kruberg <go...@gu...> wrote: > Hi, > > I have tried to take all points into consideration and I would like to hold > a new design out for further comment. Here: > http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=+Robostix Looks much better. > I revised the board to use 2mm spacing on all connectors except the servos, > uarts, and I2C. Servos seem to universally use the 0.100" spacing. > Can I do 0.100" board that's bigger? Yes-- but is 2.00mm pitch OK (versus > 2.54mm == 0.100")? I think that 2mm pitch is fine. > I have also borought out power and ground adjacent to all signals: AGND and > AVCC to the ADC pins, VCC5 to the UARTs, V_MOTOR and GND to the servos, and > V_BATT to the remaining power pins. I would especially appreciate comment > on this as it pertains to the overall power strategy; namely, that V_BATT is > provided as a power source bus, reasonably regulated at 5V and providing 1A > total. Vcc is 3.3 and is intended for this board only; Vcc5 similarly. > The UART arrangement is a little different, but allows power and ground as > well as the chance to jumper level-shifted PXA signals to the ATmega128. > The SPI bus is strictly between the PXA and ATmega128 for communication and > boot-download at this point, with the PXA as the master and thus limited to > 3.6864MHz per the intel docs. I'm confused by your power stuff. If I'm reading your comments above correctly, then V_BATT = 5v Vcc5 = 5v Vcc3.3 = 3.3v However, on the schematic you show Vcc5 as coming out of a MIC5255, which doesn't appear to make a 5v device, and you can't put 5v in and get 5v out anyways. It's important that the voltage present on the connectors be the same as the voltage that the ATMega128 is being driven with (i.e. V_BATT = Vcc5) (the whole purpose of having the +5 on the conenctor is so that it could be connected through a sensor to the signal pin). So if there's some onboard voltage regulator that's taking the power jack and going down to 5v, then the power jack voltage CAN'T be put on the connectors. If you're assuming that the power jack is providing 5v regulated, then you wouldn't need an onboard 5v regulator, just a 3.3v one for the level shifters. > Have I missed anything major? I still think you're missing the pullup resistors on the X_SCL and X_SDA signals. The PCA9517 data sheet shows that pullups are needed on both sides. The schematic shows X_MISO connecting to ATM_MISO and X_MOSI connecting to ATM_MOSI, shouldn't they cross over? i.e. X_MISO to ATM_MOSI and X_MOSI to ATM_MISO. > Finally, you may note that there are still a few lines open. Any > selections? Oh, and I think that I will bring out the PA onto unpopulated > pads on the reverse side. It would be good to have at least one output pin (say PE2) from the ATMega go through the voltage shifter and connect to an input GPIO pin on the gumstix, so that the ATMega could grab the attention of the gumstix (by configuring the gumstix GPIO to cause an interrupt). Since SPI is driven by the master (i.e. the gumstix) it can easily interrupt the ATMega. It would also be good to take one I/O pin on the ATMega (say PD5) and connect it to an LED on the board (useful for a heartbeat). I see that there are 3 extra pins on the AT_INTS connector. If you don't get anything else for these, you could always connect ALE, RD, WR to them since they're also available as Port G pins. Having PA0 thru PA7 brought out to pads on the back would be nice. It would be good if the pins required to use the USB connection were available so the circuitry could be added if desired (this would be part of the pads on the back you were talking about). I'd like to propose a slightly different layout for the AT_UARTS. The way it's currently done, you'd need to find 2x2 1.25mm pitch connectors. If such connectors are readily available, then I'm happy with the current layout, otherwise, I'd propose using a layout where each connector is a 1x4 rather than a 2x2. It would also be nice if it used the same 2mm pitch as the rest of the connections (I was able to find 2x2 connectors at 2mm pitch). The 1x4 layout would be something like this: GND VCC5 IR_RXD_5V ATM_TX0 IR_TXD_5V ATM_RX0 VCC5 GND GND VCC5 ATM_SDA ATM_TX1 ATM_SCL ATM_RX1 VCC5 GND which still allows the serial connectors to all be wired the same and allows jumpering for IR_TX/RX <=> ARM_RX/TX0 > > Thanks for the comments, Happy to oblige :) -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Dave H. <dhy...@gm...> - 2005-02-25 21:14:02
|
> The schematic shows X_MISO connecting to ATM_MISO and X_MOSI > connecting to ATM_MOSI, shouldn't they cross over? i.e. X_MISO to > ATM_MOSI and X_MOSI to ATM_MISO. Sorry - the schematic is correct. The pins change direction depending on whether you're a master or a slave. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: mgross <mar...@th...> - 2005-02-26 14:07:39
|
On Friday 25 February 2005 07:54, Gordon Kruberg wrote: > Hi, > > I have tried to take all points into consideration and I would like to > hold a new design out for further comment.=A0 Here: > http://www.gumstix.org/tikiwiki/tiki-editpage.php?page=3D+Robostix > > I revised the board to use 2mm spacing on all connectors except the servo= s, > uarts, and I2C.=A0 Servos seem to universally use the 0.100" spacing. > > Can I do 0.100" board that's bigger?=A0 Yes-- but is 2.00mm pitch OK (ver= sus > 2.54mm =3D=3D 0.100")? I guess, but it will be harder for saps like me to connect my sensors and=20 motors too. I have some robots that use > 2 servos, and > 6 analog sensors. My current robot that I am working on will need to connect the following=20 things to the AVR side of the system. 1 PWM H-bridge=20 2 servos 2 I2C acoustic proximity sensors 1 I2C digital compas 1 interrupt generating wheel encoder 2 GPIO bump sensors 1 serial port CMU-cam Oh and this robot will be moving and I can't have my blue-wire connections = to=20 "PADS" come off when the thing is running. So please, please when you run the AVR pin outs to "pads" include a through= =20 hole site as well I can attach a wire to. It can be a small hole, just lar= ge=20 enough to put a wire through with a good solid electrical and mechanical=20 connection. BTW, I think this robo stick idea kicks ass. =20 =2D-mgross > > I have also borought out power and ground adjacent to all signals: AGND a= nd > AVCC to the ADC pins, VCC5 to the UARTs, V_MOTOR and GND to the servos, a= nd > V_BATT to the remaining power pins.=A0=A0 I would especially appreciate c= omment > on this as it pertains to the overall power strategy; namely, that V_BATT > is provided as a power source bus, reasonably regulated at 5V and providi= ng > 1A total.=A0 Vcc is 3.3 and is intended for this board only; Vcc5 similar= ly. > > The UART arrangement is a little different, but allows power and ground as > well as the chance to jumper level-shifted PXA signals to the ATmega128. > > The SPI bus is strictly between the PXA and ATmega128 for communication a= nd > boot-download at this point, with the PXA as the master and thus limited = to > 3.6864MHz per the intel docs. > > Have I missed anything major? > > Finally, you may note that there are still a few lines open.=A0 Any > selections?=A0 Oh, and I think that I will bring out the PA onto unpopula= ted > pads on the reverse side. > > Thanks for the comments, > > Gordon > ------------------------------------------------------- SF email is > sponsored by - The IT Product Guide Read honest & candid reviews on > hundreds of IT Products from real users. Discover which products truly li= ve > up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=3D6595&alloc_id=3D14396&op=3Dclick > _______________________________________________ gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |