From: Keith S. <ks...@cs...> - 2007-02-06 17:08:42
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Hi all, I'm trying to get i2c working with my gumstix and robostix. Following the directions on the wiki, I eventually got to the stage of running i2c-test to check the connection between the gumstix and robostix. I get the following results: [root@gumstix cf]# uisp --erase --upload if=i2c-test.hex Atmel AVR ATmega128 is found. Erasing device ... Reinitializing device Atmel AVR ATmega128 is found. Uploading: flash [root@gumstix cf]# ./i2c-test gumstix: SCL: 0 SDA: 0 gumstix: SCL: 0 SDA: 0 robostix: SCLw: Z SCLr: 1 SDAw: Z SDAr: 1 DDRD: 0 PIND: 3, PORTD: 0 This is clearly not the expected result. Any ideas as to what is going on here? Also, when I try to access the i2c bus, I get a slave timeout message. I suspect the two are related. Any help appreciated. Keith |
From: Dave H. <dhy...@gm...> - 2007-02-06 17:59:53
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HI Keith, > I'm trying to get i2c working with my gumstix and robostix. Following the > directions on the wiki, I eventually got to the stage of running i2c-test > to check the connection between the gumstix and robostix. I get the > following results: ...snip... > [root@gumstix cf]# ./i2c-test > gumstix: SCL: 0 SDA: 0 > gumstix: SCL: 0 SDA: 0 > robostix: SCLw: Z SCLr: 1 SDAw: Z SDAr: 1 DDRD: 0 PIND: 3, PORTD: 0 So the first thing that needs to be resolved is that the gumstix is reporting SCL and SDA as 0. Are the i2c modules loaded? (i.e. do they show up in lsmod output?) The i2c-test is only valid when the the i2c modules are NOT loaded. Are you powering the robostix? The power jack on the robostix isn't wired in parallel with the power jacks on other boards, so the robostix needs to be powered in order for stuff to work properly. Try unplugging the robostix and rerunning the i2c-test (you may need to use an alternate daugthercard like the tweener/waysmall/etc). You should at least see the gumstix reporting 1 and 1 for SDA and SCL. It's also weird that the robostix is reporting that it's seeing 1 and 1 on the SDA and SCL while the gumstix is reporting 0's (although this might be caused by not powering the robostix). -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Keith S. <ks...@cs...> - 2007-02-06 18:30:49
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Hi Dave, On Feb 6, 2007, at 12:59 PM, Dave Hylands wrote: > HI Keith, > >> I'm trying to get i2c working with my gumstix and robostix. >> Following the >> directions on the wiki, I eventually got to the stage of running >> i2c-test >> to check the connection between the gumstix and robostix. I get the >> following results: > ...snip... >> [root@gumstix cf]# ./i2c-test >> gumstix: SCL: 0 SDA: 0 >> gumstix: SCL: 0 SDA: 0 >> robostix: SCLw: Z SCLr: 1 SDAw: Z SDAr: 1 DDRD: 0 PIND: 3, PORTD: 0 > > So the first thing that needs to be resolved is that the gumstix is > reporting SCL and SDA as 0. > > Are the i2c modules loaded? (i.e. do they show up in lsmod output?) > The i2c-test is only valid when the the i2c modules are NOT loaded. > I removed them, and verified that they are gone via lsmod. > Are you powering the robostix? The power jack on the robostix isn't > wired in parallel with the power jacks on other boards, so the > robostix needs to be powered in order for stuff to work properly. > The wall wort is plugged into the robostix. Eventually, batteries will be plugged into the robostix. > Try unplugging the robostix and rerunning the i2c-test (you may need > to use an alternate daugthercard like the tweener/waysmall/etc). You > should at least see the gumstix reporting 1 and 1 for SDA and SCL. > I'll try this either later today or tomorrow. thanks for your help, Keith > It's also weird that the robostix is reporting that it's seeing 1 and > 1 on the SDA and SCL while the gumstix is reporting 0's (although this > might be caused by not powering the robostix). > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your > job easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Keith S. <ks...@cs...> - 2007-02-07 20:16:02
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OK. So, I plugged the gumstix into another robostix and a waysmall, and ran i2c-test with results of gumstix: SCL: 0 SDA: 0 I also tried rebuilding rootfs from scratch, but that didn't help. Any ideas? Keith On Feb 6, 2007, at 12:59 PM, Dave Hylands wrote: > HI Keith, > >> I'm trying to get i2c working with my gumstix and robostix. >> Following the >> directions on the wiki, I eventually got to the stage of running >> i2c-test >> to check the connection between the gumstix and robostix. I get the >> following results: > ...snip... >> [root@gumstix cf]# ./i2c-test >> gumstix: SCL: 0 SDA: 0 >> gumstix: SCL: 0 SDA: 0 >> robostix: SCLw: Z SCLr: 1 SDAw: Z SDAr: 1 DDRD: 0 PIND: 3, PORTD: 0 > > So the first thing that needs to be resolved is that the gumstix is > reporting SCL and SDA as 0. > > Are the i2c modules loaded? (i.e. do they show up in lsmod output?) > The i2c-test is only valid when the the i2c modules are NOT loaded. > > Are you powering the robostix? The power jack on the robostix isn't > wired in parallel with the power jacks on other boards, so the > robostix needs to be powered in order for stuff to work properly. > > Try unplugging the robostix and rerunning the i2c-test (you may need > to use an alternate daugthercard like the tweener/waysmall/etc). You > should at least see the gumstix reporting 1 and 1 for SDA and SCL. > > It's also weird that the robostix is reporting that it's seeing 1 and > 1 on the SDA and SCL while the gumstix is reporting 0's (although this > might be caused by not powering the robostix). > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your > job easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Dave H. <dhy...@gm...> - 2007-02-07 22:27:07
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Hi Keith, > OK. So, I plugged the gumstix into another robostix and a waysmall, > and ran i2c-test with results of > > gumstix: SCL: 0 SDA: 0 > > I also tried rebuilding rootfs from scratch, but that didn't help. > Any ideas? If you just purchased it, then my guess is that there's a problem on the gumstix motherboard, and I'd return it. It sounds like both of those lines are being grounded. The newer gumstix (They have the New 60pin connector) include pullups on the main board, so with a waysmall plugged in you should be seeing SDA and SCL both being 1. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: DJ D. <dj...@de...> - 2007-02-07 22:45:55
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"Dave Hylands" <dhy...@gm...> writes: > It sounds like both of those lines are being grounded. The newer > gumstix (They have the New 60pin connector) include pullups on the > main board, They do? What value, and how can we verify this? It may explain an anomoly I've been seeing in my project. |
From: Dave H. <dhy...@gm...> - 2007-02-08 00:21:26
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Hi DJ, > "Dave Hylands" <dhy...@gm...> writes: > > It sounds like both of those lines are being grounded. The newer > > gumstix (They have the New 60pin connector) include pullups on the > > main board, > > They do? What value, and how can we verify this? It may explain an > anomoly I've been seeing in my project. 68K ohms See this mail thread: http://thread.gmane.org/gmane.linux.distributions.gumstix.general/7253/focus=7296 -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: DJ D. <dj...@de...> - 2007-02-08 01:12:59
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"Dave Hylands" <dhy...@gm...> writes: > 68K ohms Ok, thanks. IMHO too high for i2c, but even without my resistors, it didn't solve my anomaly (the r8c/1b I'm talking to doesn't see the i2c signals change in the i2c module, although the gpio module sees the change). |
From: Patrick D. <wp...@gm...> - 2007-02-08 03:12:25
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On 07 Feb 2007 20:12:55 -0500, DJ Delorie <dj...@de...> wrote: > > "Dave Hylands" <dhy...@gm...> writes: > > 68K ohms > > Ok, thanks. IMHO too high for i2c, but even without my resistors, it > didn't solve my anomaly (the r8c/1b I'm talking to doesn't see the i2c > signals change in the i2c module, although the gpio module sees the > change). 68K is an order of magnitude higher than anything I've ever seen for I2C pullups. However, I've only been exposed to I2C at one place, so there is a certain amount of corporate knowledge that has been propagated to numerous designs. Still, I agree with DJ, it seems awfully weak. Where did 68K come from anyway? --wpd |
From: Dave H. <dhy...@gm...> - 2007-02-08 04:45:53
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Hi guys, > 68K is an order of magnitude higher than anything I've ever seen for > I2C pullups. However, I've only been exposed to I2C at one place, so > there is a certain amount of corporate knowledge that has been > propagated to numerous designs. Still, I agree with DJ, it seems > awfully weak. > > Where did 68K come from anyway? I think Gordon just picked something weak so that it wouldn't have a dominant effect on whatever else is on the bus. There is an i2c device on the gumstix motherboard (something to do with the voltage regulator). With no pullups you can't talk to it at all. 68K also doesn't consume much power. I wouldn't rely on those pullups for any external devices, and would put much lower values (the robostix has 10k pullups, the i2c spec suggests even lower values). -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Keith S. <ks...@cs...> - 2007-02-10 22:53:52
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Hi Dave, I'm clearly doing something wrong. I borrowed a different gumstix and robostix, rebuild the rootfs, and tried running i2c-test. Same results as before. Also, I still get SCL: 0 and SDA: 0 when connecting to a waysmall board. Any ideas? Keith On Wed, 2007-02-07 at 14:26 -0800, Dave Hylands wrote: > Hi Keith, > > > OK. So, I plugged the gumstix into another robostix and a waysmall, > > and ran i2c-test with results of > > > > gumstix: SCL: 0 SDA: 0 > > > > I also tried rebuilding rootfs from scratch, but that didn't help. > > Any ideas? > > If you just purchased it, then my guess is that there's a problem on > the gumstix motherboard, and I'd return it. > > It sounds like both of those lines are being grounded. The newer > gumstix (They have the New 60pin connector) include pullups on the > main board, so with a waysmall plugged in you should be seeing SDA and > SCL both being 1. > |
From: Dave H. <dhy...@gm...> - 2007-02-11 06:28:21
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HI Keith, > I'm clearly doing something wrong. I borrowed a different gumstix and > robostix, rebuild the rootfs, and tried running i2c-test. Same results > as before. Also, I still get SCL: 0 and SDA: 0 when connecting to a > waysmall board. Any ideas? Hmm. Let me take a look at it. It could be the mmap problem with recent buildroots. I haven't used i2c-test in a while, so it might be broken for the same reasons pxaregs doesn't work. Yeah - I took a look at i2c-test again, and it does, in fact, use mmap. Sheepishly lurking away.... -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Keith S. <ks...@cs...> - 2007-02-13 03:26:39
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Hi Dave, To further your suspicion that mmap is the culprit, I downloaded and installed revision 1093 on all the gumstix and robostix combinations and everything worked fine. Keith On Feb 11, 2007, at 1:27 AM, Dave Hylands wrote: > HI Keith, > >> I'm clearly doing something wrong. I borrowed a different gumstix >> and >> robostix, rebuild the rootfs, and tried running i2c-test. Same >> results >> as before. Also, I still get SCL: 0 and SDA: 0 when connecting to a >> waysmall board. Any ideas? > > Hmm. Let me take a look at it. It could be the mmap problem with > recent buildroots. I haven't used i2c-test in a while, so it might be > broken for the same reasons pxaregs doesn't work. > > Yeah - I took a look at i2c-test again, and it does, in fact, use > mmap. > > Sheepishly lurking away.... > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your > job easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Craig H. <cr...@gu...> - 2007-02-13 06:02:41
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On Feb 12, 2007, at 7:26 PM, Keith Sullivan wrote: > To further your suspicion that mmap is the culprit, I downloaded and > installed revision 1093 on all the gumstix and robostix combinations > and everything worked fine. I'll re-look at the mmap problem. It's quite likely to have been fixed by now upstream, I imagine. C |