From: DylanB <dbr...@un...> - 2010-04-13 05:21:31
|
Hello again Dave, Just a thought relating to my troubles. The level shifter I am using can convert "any" volatge to rs232 serial by using the voltage (Vcc) that powers the board. It seems that the Vcc on the robostix board, even for the Verdex STUART, is +5V. Presumably this means that, by design, the level shifter is going to be outputting and expecting 5V signals rather than the 3.3 that the Verdex can understand. Maybe this is what is going on. I don't know if it makes sense though that sertest still works. How can I access 3.3V to power the shifter? Dylan. -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28219224.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-04-13 05:39:26
|
Hi Dylan, On Mon, Apr 12, 2010 at 10:21 PM, DylanB <dbr...@un...> wrote: > > Hello again Dave, > > Just a thought relating to my troubles. > The level shifter I am using can convert "any" volatge to rs232 serial by > using the voltage (Vcc) that powers the board. It seems that the Vcc on the > robostix board, even for the Verdex STUART, is +5V. Presumably this means > that, by design, the level shifter is going to be outputting and expecting > 5V signals rather than the 3.3 that the Verdex can understand. Maybe this is > what is going on. I don't know if it makes sense though that sertest still > works. > How can I access 3.3V to power the shifter? Yeah - the robostix has level shifters to convert the STUART signals to/from the 3.3v on the verdex to 5v on the robostix connector. So your level converter should be converting to/from 5v and RS-232. The robostix board does the conversion from 5v to 3.3v. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: Dave H. <dhy...@gm...> - 2010-04-19 03:31:59
|
Hi Dylan, On Sun, Apr 18, 2010 at 7:44 PM, DylanB <dbr...@un...> wrote: > > Dave, > > My setup is as you have described: Verdex, Robostix, external IMU connected > to STUART via level shifter. > The level shifter works with sertest (RX TX crossed). > > When I try to run the IMU code, which works on my laptop, on the Verdex > strange things happen. > With no level shifter attached the code runs. > With the level shifter attached the code does not run at all, i.e. not even > a printf before I try to open the port. The IMU is not even connected here > so I don't know what is causing all the trouble. I have tried a couple of > level shifters. Does this seem very odd? This sounds very odd. It sounds like something is miswired. Can you describe exactly how you have the level shifter connected? -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: DylanB <dbr...@un...> - 2010-04-19 04:52:36
|
Hi Dave, OK the level shifter can be seen in this link: http://www.sparkfun.com/commerce/product_info.php?products_id=8780 The link has a schematic that Sparkfun provides. Robostix Board (PXA ST) Level Shifter Rx Tx V VCC Tx Rx G GND I have looked at it with a magnifying glass and I can't see any jumpers. The other end has a DB9. The cable that I use to connect the DB9 to my IMU has been tested and works on my laptop. This behaviour seems so strange. I'm starting to wonder whether I have stuffed up something in the Robostix by miswiring or something like that. Dylan. -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28287164.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: DylanB <dbr...@un...> - 2010-04-19 05:19:21
|
Not sure if this was in the original message. Sorry if it is a double post. Some observations: Using a multimeter I have put one probe on PXA ST G and then the other on the three remaining pins, these are the results. 2nd Probe Position (PXA ST) Reading With Level Shifter TX 5V V 5V RX 5V ******* No Level Shifter TX 5V V 5V RX 0V ******** I'm not sure if this helps. The Robostix is running i2c-io. -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28287282.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-04-19 15:47:32
|
Hi Dylan, On Sun, Apr 18, 2010 at 10:19 PM, DylanB <dbr...@un...> wrote: > > Not sure if this was in the original message. Sorry if it is a double post. > > Some observations: > Using a multimeter I have put one probe on PXA ST G and then the other on > the three remaining pins, these are the results. > > 2nd Probe Position (PXA ST) Reading > > With Level Shifter > TX 5V > V 5V > RX 5V > ******* > > No Level Shifter > TX 5V > V 5V > RX 0V > ******** So that looks reasonable given nothing is hooked up. If you were to connect the Tx to Rx on the DB9 side, you should see the RX signal come upto 5v. And just to clarify the pin assignments. Pin 1 - STUART Rx Pin 3 - +5 Pin 5 - STUART Tx Pin 7 - Gnd (pin numbers are silkscreened on the topside of the board). I know that on some older robostix boards (prior to rev 1131), pin 2 is supposed to be ground, but it doesn't connect to the ground plane. See <http://docwiki.gumstix.com/index.php/Robostix_modifications> "Ground wire fix". If you're using pin 7 you should be fine. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: DylanB <dbr...@un...> - 2010-04-28 00:38:53
|
Hi Dave, I have the pins setup as you suggest. A while ago I asked someone who has the same hardware setp as me, incuding IMU, to test my code on their system. They did and it worked fine. Presumably this means that there is no issue with the C code. This leads me to believe that the problem will probably be in one of four areas: 1) Levelshifter not functioning. 2) Build environment not targeting system correctly. 3) Robostix malfunctioning. 4) Verdex malfunctioning. Testing procedure: 1) Use CRO to check the voltages. If they are incorrect I will try a different level shifter brand/style. 2) I will send my compiled file to someone with the same setup and see whether they are able to run the code. I will erase all the temporary files created and rebuild the basic image. 3) Test some sample code. Not sure what else to do. 4) ?? Do you have any suggestions about how I should go about checking the system? Dylan. Dave Hylands wrote: > > Hi Dylan, > > On Sun, Apr 18, 2010 at 10:19 PM, DylanB <dbr...@un...> > wrote: >> >> Not sure if this was in the original message. Sorry if it is a double >> post. >> >> Some observations: >> Using a multimeter I have put one probe on PXA ST G and then the other on >> the three remaining pins, these are the results. >> >> 2nd Probe Position (PXA ST) Reading >> >> With Level Shifter >> TX >> 5V >> V >> 5V >> RX >> 5V >> ******* >> >> No Level Shifter >> TX >> 5V >> V >> 5V >> RX 0V >> ******** > > So that looks reasonable given nothing is hooked up. If you were to > connect the Tx to Rx on the DB9 side, you should see the RX signal > come upto 5v. > > And just to clarify the pin assignments. > > Pin 1 - STUART Rx > Pin 3 - +5 > Pin 5 - STUART Tx > Pin 7 - Gnd > > (pin numbers are silkscreened on the topside of the board). > > I know that on some older robostix boards (prior to rev 1131), pin 2 > is supposed to be ground, but it doesn't connect to the ground plane. > See > <http://docwiki.gumstix.com/index.php/Robostix_modifications> "Ground > wire fix". If you're using pin 7 you should be fine. > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28383589.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-04-28 03:20:14
|
Hi Dylan, On Tue, Apr 27, 2010 at 5:22 PM, DylanB <dbr...@un...> wrote: > > Hi Dave, > > I have the pins setup as you suggest. > > A while ago I asked someone who has the same hardware setp as me, incuding > IMU, to test my code on their system. They did and it worked fine. > Presumably this means that there is no issue with the C code. This leads me > to believe that the problem will probably be in one of four areas: > > 1) Levelshifter not functioning. > 2) Build environment not targeting system correctly. > 3) Robostix malfunctioning. > 4) Verdex malfunctioning. > > Testing procedure: > > 1) Use CRO to check the voltages. If they are incorrect I will try a > different level shifter brand/style. CRO? Is that an oscilloscope? Yeah the logic level signal for the Tx pin should be high (5v) when the system is idle. For RS-232 this corresponds to a voltage <= 0v (it's supposed to be -3v to -25v IIRC but lots of level shifters consider <= 0v to be a logic 1. Try a few different grounds as well. Make sure you try the actual ground pin you're using as well as some others on the board. A bad ground (i.e. cold solder joint) can cause all kinds of weird problems. > 2) I will send my compiled file to someone with the same setup and see > whether they are able to run the code. I will erase all the temporary files > created and rebuild the basic image. > 3) Test some sample code. Not sure what else to do. sertest is some sample code that should work fine. Obviously, if you had a second robostix or a second level shifter you can swap stuff around and see what makes the problem change. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: DylanB <dbr...@un...> - 2010-04-28 13:56:40
|
Hi Dave, Yeah its an oscilloscope. I still can't find any info on how to change the kernel version that my build environment is targeting. Also whenever I bitbake recipes, i.e. helloworld or something to read the imu, it works but says "completed 229 of which 216 tasks didn't need to be rerun" and it appears to start at task 174. I'm sure it didn't always do that. Sertest appears to work but I have only really tested it using a loop back. I also used another computer running putty but that had mixed results, i.e. I could send characters but I wasn't able to receive any. Thanks, Dylan. Dave Hylands wrote: > > Hi Dylan, > > On Tue, Apr 27, 2010 at 5:22 PM, DylanB <dbr...@un...> > wrote: >> >> Hi Dave, >> >> I have the pins setup as you suggest. >> >> A while ago I asked someone who has the same hardware setp as me, >> incuding >> IMU, to test my code on their system. They did and it worked fine. >> Presumably this means that there is no issue with the C code. This leads >> me >> to believe that the problem will probably be in one of four areas: >> >> 1) Levelshifter not functioning. >> 2) Build environment not targeting system correctly. >> 3) Robostix malfunctioning. >> 4) Verdex malfunctioning. >> >> Testing procedure: >> >> 1) Use CRO to check the voltages. If they are incorrect I will try a >> different level shifter brand/style. > > CRO? Is that an oscilloscope? > > Yeah the logic level signal for the Tx pin should be high (5v) when > the system is idle. For RS-232 this corresponds to a voltage <= 0v > (it's supposed to be -3v to -25v IIRC but lots of level shifters > consider <= 0v to be a logic 1. > > Try a few different grounds as well. Make sure you try the actual > ground pin you're using as well as some others on the board. A bad > ground (i.e. cold solder joint) can cause all kinds of weird problems. > >> 2) I will send my compiled file to someone with the same setup and see >> whether they are able to run the code. I will erase all the temporary >> files >> created and rebuild the basic image. >> 3) Test some sample code. Not sure what else to do. > > sertest is some sample code that should work fine. > > Obviously, if you had a second robostix or a second level shifter you > can swap stuff around and see what makes the problem change. > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------------ > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28387971.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-04-28 14:36:54
|
Hi Dylan, On Wed, Apr 28, 2010 at 6:56 AM, DylanB <dbr...@un...> wrote: > > Hi Dave, > > Yeah its an oscilloscope. > > I still can't find any info on how to change the kernel version that my > build environment is targeting. Sorry - I don't know either - although I'm pretty sure it's been discussed. I did some poking around and it appears to be set in the conf/machine/include/gumstix.inc There's a line that says: PREFERRED_VERSION_gumstix-kernel = "2.6.21" > Also whenever I bitbake recipes, i.e. helloworld or something to read the > imu, it works but says "completed 229 of which 216 tasks didn't need to be > rerun" and it appears to start at task 174. I'm sure it didn't always do > that. I think if you have dependencies, then this means that the dependencies are already built so it just skips them. > Sertest appears to work but I have only really tested it using a loop back. > I also used another computer running putty but that had mixed results, i.e. > I could send characters but I wasn't able to receive any. That sounds very much like a grounding problem. loopback doesn't need any grounds, but connecting to another computer does. You should be able to connect the level shifter to the PC, with just power and ground coming from the robostix, and then loop back the logic level side of the level shifter. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: DylanB <dbr...@un...> - 2010-05-13 13:18:46
|
Setup: XM4, robostix, wifi. I'm trying to power 4 hobby servos and two brushless motors. I'm not sure if it is best to power the stack with 5v from one of the speed controllers or cut the jumper and power the PWMs and the board seperately using another battery for the board. I have done the jumper mod shown in the robostix wiki allowing the whole stack to be powered from the robostix jack. Dylan. -- View this message in context: http://old.nabble.com/Robostix-IMU-Serial-tp25185790p28547397.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-05-13 14:42:50
|
Hi Dylan, On Thu, May 13, 2010 at 6:18 AM, DylanB <dbr...@un...> wrote: > > Setup: XM4, robostix, wifi. > I'm trying to power 4 hobby servos and two brushless motors. I'm not sure if > it is best to power the stack with 5v from one of the speed controllers or > cut the jumper and power the PWMs and the board seperately using another > battery for the board. I have done the jumper mod shown in the robostix wiki > allowing the whole stack to be powered from the robostix jack. You really need to figure out how much current would be used. Hobby servos can draw several hundred milliamps, depending on the servo. And brushless motors - it really depends. I know I put a warning on one of the wiki pages which is actually more dire that it needs to be. If you leave the jumper in place, then V_MOTOR comes directly from the power jack and doesn't go through any of the voltage regulators, so it actually isn't too bad of an option. I don't recall what the board traces are rated for , but I seem to recall something like a couple amps or so. Keep this is mind. Often things like your brushless motors may be drawing more than that, and that could cause problems. If you're thinking about using battery power, I highly recommend using a separate supply. When the motors first start up, they will often draw many amps which can cause the battery voltage to dip - maybe only for a few milliseconds - but this is often enough to reset the microcontroller. So you can try using a single battery, if you find that the robostix is resetting on you when motors start, then this is where using the second battery becomes beneficial. Also - if you do go with a single battery, then you want to wire things up in a star configuration. By this, I mean you want to start at the battery, and run a power and ground to the robotix. Then have a separate power and ground for the servos, and another power and ground for the brushless motors (maybe a separate one for each motor). You should also twist the power and ground lines together between the battery and each load. With the star ground, the current rushes seen on the grounds to the motors will have less impact on the other grounds, and the twisting helps with reducing the PWM noise. Here's a PDF that gives a better explanation of some of this: <http://www.pacsci.com/support/documents/mtd/d-10.pdf> -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |