From: emmers369 <emm...@ya...> - 2010-07-07 16:21:35
|
Hi, I have an Overo Air and a Pinto expansion board. I am trying to use the I2C to connect to several external sensors. I have powered the board with a 9V and also tried an 11.1V battery and have checked that I am getting both VCC = 3.3V and V_Logic = 1.8V. When I try to run my program it appears to run fine but it fails to collect data from the sensors. I have the same exact configuration on the Summit board and it works perfectly. Other than miss-wiring, which I have checked multiple times, is there anything that I might be missing going between the boards? Is there something that I need to take into account since I am using a battery on the pinto instead of the 5V wall charger? Any suggestions would be greatly appreciated. Emily -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29098317.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-07-07 16:58:27
|
Hi Emily, On Wed, Jul 7, 2010 at 9:21 AM, emmers369 <emm...@ya...> wrote: > > Hi, > I have an Overo Air and a Pinto expansion board. I am trying to use the I2C > to connect to several external sensors. I have powered the board with a 9V > and also tried an 11.1V battery and have checked that I am getting both VCC > = 3.3V and V_Logic = 1.8V. When I try to run my program it appears to run > fine but it fails to collect data from the sensors. I have the same exact > configuration on the Summit board and it works perfectly. Other than > miss-wiring, which I have checked multiple times, is there anything that I > might be missing going between the boards? Is there something that I need to > take into account since I am using a battery on the pinto instead of the 5V > wall charger? Any suggestions would be greatly appreciated. How did determine the SCL and SDA pins on the pinto? They are silkscreened on the side with the buttons, and the vias correspond to the hole underneath the label. I'm assuming that you connected SDA, SCL and ground from the Pinto and that you're using appropriate level shifters? Do you have pullups? The summit board has 1.5K pullups (to 1.8v) on SDA and SCL lines which the Pinto doesn't. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: emmers369 <emm...@ya...> - 2010-07-07 17:08:15
|
Hi Dave, I used the SCL and SDA lines from the Pinto as well as the 3.3V and 1.8V power pins. I used the 3.3V pins to power the sensors and the 1.8V to power the I2C communication. I did the same thing on the other board and it worked fine, I would think I was negating those pull up resistors by doing it this way. Emily Dave Hylands wrote: > > Hi Emily, > > On Wed, Jul 7, 2010 at 9:21 AM, emmers369 <emm...@ya...> wrote: >> >> Hi, >> I have an Overo Air and a Pinto expansion board. I am trying to use the >> I2C >> to connect to several external sensors. I have powered the board with a >> 9V >> and also tried an 11.1V battery and have checked that I am getting both >> VCC >> = 3.3V and V_Logic = 1.8V. When I try to run my program it appears to run >> fine but it fails to collect data from the sensors. I have the same exact >> configuration on the Summit board and it works perfectly. Other than >> miss-wiring, which I have checked multiple times, is there anything that >> I >> might be missing going between the boards? Is there something that I need >> to >> take into account since I am using a battery on the pinto instead of the >> 5V >> wall charger? Any suggestions would be greatly appreciated. > > How did determine the SCL and SDA pins on the pinto? They are > silkscreened on the side with the buttons, and the vias correspond to > the hole underneath the label. > > I'm assuming that you connected SDA, SCL and ground from the Pinto and > that you're using appropriate level shifters? > > Do you have pullups? > > The summit board has 1.5K pullups (to 1.8v) on SDA and SCL lines which > the Pinto doesn't. > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29098794.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-07-07 17:23:19
|
Hi Emily, On Wed, Jul 7, 2010 at 10:08 AM, emmers369 <emm...@ya...> wrote: > > Hi Dave, > I used the SCL and SDA lines from the Pinto as well as the 3.3V and 1.8V > power pins. I used the 3.3V pins to power the sensors and the 1.8V to power > the I2C communication. I did the same thing on the other board and it worked > fine, I would think I was negating those pull up resistors by doing it this > way. I2c relies on the pullup resistors. The SDA and SCL signals are only capable of driving a signal low, they can't drive the signal back high again. That's the purpose of the pullup resistors. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: emmers369 <emm...@ya...> - 2010-07-07 17:51:08
|
Ah right, you are quite correct, I was not thinking. However, when I look at where the pull-up resistors should be on the Summit board, those are not populated. The same place exists on the Pinto as well but again are not populated. My sensors are on evaluation boards which have the pull-up resistors instead. Since they are on the boards that are getting switched, I would not expect this to be a problem. Emily Dave Hylands wrote: > > Hi Emily, > > On Wed, Jul 7, 2010 at 10:08 AM, emmers369 <emm...@ya...> wrote: >> >> Hi Dave, >> I used the SCL and SDA lines from the Pinto as well as the 3.3V and 1.8V >> power pins. I used the 3.3V pins to power the sensors and the 1.8V to >> power >> the I2C communication. I did the same thing on the other board and it >> worked >> fine, I would think I was negating those pull up resistors by doing it >> this >> way. > > I2c relies on the pullup resistors. The SDA and SCL signals are only > capable of driving a signal low, they can't drive the signal back high > again. That's the purpose of the pullup resistors. > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29099051.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-07-07 18:06:04
|
Hi Emily, On Wed, Jul 7, 2010 at 10:50 AM, emmers369 <emm...@ya...> wrote: > > Ah right, you are quite correct, I was not thinking. However, when I look at > where the pull-up resistors should be on the Summit board, those are not > populated. The same place exists on the Pinto as well but again are not > populated. My sensors are on evaluation boards which have the pull-up > resistors instead. Since they are on the boards that are getting switched, I > would not expect this to be a problem. So I took a look at the board layout for the Pinto, and I don't see any pullup resistors (nor spots to put them) for the SDA and SCL lines. If you have some on the sensors and they're pulling up to 1.8v then that should be fine. My summit is rev 2185 so it doesn't have any pullups, nor the PCA9306 that is present in rev 2563. However, if your sensors are 3.3v then they might not be seeing 1.8v as a logic high if you don't have level shifters. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: Søren S. C. <li...@ss...> - 2010-07-07 21:42:45
|
Hi Emily, As already stated by Deve, for a 3V3 powered I2C device you would normally need to pull-up the I2C lines to the same level. Normally I2C HIGH is considered 60% of VCC = 2.0V for a 3V3 powered sensor (unless it has a special supply for IO, which you have connected to the 1V8 supply :-). You are however not allowed to pull the I2C lines to 3V3 due to the OMAP using 1V8 logic => You need a level converter. You can use i.e. TXS0102 from TI... Good luck Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk |
From: emmers369 <emm...@ya...> - 2010-07-08 18:50:04
|
Hi Søren, My device does have a special supply IO pin which I am supplying with the 1.8V pin from the Gumstix and am powering the sensors with 3.3Vs, and the sensors have pullup resistors. I am missing something? Emily Søren Steen Christensen wrote: > > Hi Emily, > > As already stated by Deve, for a 3V3 powered I2C device you would normally > need to pull-up the I2C lines to the same level. > Normally I2C HIGH is considered 60% of VCC = 2.0V for a 3V3 powered sensor > (unless it has a special supply for IO, which you have connected to the > 1V8 > supply :-). > > You are however not allowed to pull the I2C lines to 3V3 due to the OMAP > using 1V8 logic => You need a level converter. You can use i.e. TXS0102 > from > TI... > > Good luck > Søren > > --- > SSC Solutions ApS - Denmark - www.ssc-solutions.dk > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29110563.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Søren S. C. <li...@ss...> - 2010-07-08 20:59:43
|
Hi Emily, > My device does have a special supply IO pin which I am supplying with > the 1.8V pin from the Gumstix and am powering the sensors with 3.3Vs, and > the sensors have pullup resistors. I am missing something? In case the pull-up resistors for the sensors are connected to 3V3 you have most likely killed the I2C lines on the Gumstix/OMAP, since this does only support 1V8 operation... In case the pull-up resistors for the sensors are connected to 1V8 the sensors will most likely not be able to see a HIGH on the bus, since they are expecting a value larger than 2V0 (~60% of 3V3) being high, but they are only getting 1V8 from the pull-ups. You need to have a level-converter (i.e. TXS0102 as mentioned) in the circuit in between the sensors and the Gumstix/OMAP in a setup like this... I hope this helped you forward? Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk > -----Original Message----- > From: emmers369 [mailto:emm...@ya...] > Sent: Thursday, July 08, 2010 8:50 PM > To: gum...@li... > Subject: Re: [Gumstix-users] I2C troubles with Overo/Pinto > > > Hi Søren, > My device does have a special supply IO pin which I am supplying with > the > 1.8V pin from the Gumstix and am powering the sensors with 3.3Vs, and > the > sensors have pullup resistors. I am missing something? > Emily > > > Søren Steen Christensen wrote: > > > > Hi Emily, > > > > As already stated by Deve, for a 3V3 powered I2C device you would > normally > > need to pull-up the I2C lines to the same level. > > Normally I2C HIGH is considered 60% of VCC = 2.0V for a 3V3 powered > sensor > > (unless it has a special supply for IO, which you have connected to > the > > 1V8 > > supply :-). > > > > You are however not allowed to pull the I2C lines to 3V3 due to the > OMAP > > using 1V8 logic => You need a level converter. You can use i.e. > TXS0102 > > from > > TI... > > > > Good luck > > Søren > > > > --- > > SSC Solutions ApS - Denmark - www.ssc-solutions.dk > > > > > > --------------------------------------------------------------------- > --------- > > This SF.net email is sponsored by Sprint > > What will you do first with EVO, the first 4G phone? > > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > > _______________________________________________ > > gumstix-users mailing list > > gum...@li... > > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > > > > -- > View this message in context: http://old.nabble.com/I2C-troubles-with- > Overo-Pinto-tp29098317p29110563.html > Sent from the Gumstix mailing list archive at Nabble.com. > > > ----------------------------------------------------------------------- > ------- > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.830 / Virus Database: 271.1.1/2989 - Release Date: > 07/08/10 08:36:00 |
From: Dave H. <dhy...@gm...> - 2010-07-08 21:10:53
|
Hi Søren, On Thu, Jul 8, 2010 at 1:59 PM, Søren Steen Christensen <li...@ss...> wrote: > Hi Emily, > >> My device does have a special supply IO pin which I am supplying with >> the 1.8V pin from the Gumstix and am powering the sensors with 3.3Vs, and >> the sensors have pullup resistors. I am missing something? > > In case the pull-up resistors for the sensors are connected to 3V3 you have most likely killed the I2C lines on the Gumstix/OMAP, since this does only support 1V8 operation... > > In case the pull-up resistors for the sensors are connected to 1V8 the sensors will most likely not be able to see a HIGH on the bus, since they are expecting a value larger than 2V0 (~60% of 3V3) being high, but they are only getting 1V8 from the pull-ups. > > You need to have a level-converter (i.e. TXS0102 as mentioned) in the circuit in between the sensors and the Gumstix/OMAP in a setup like this... It sounds like the sensor Emily is using has a separate I/O voltage for the i2c. It would be worth finding out which sensor this is, just so that we can double check it. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: Søren S. C. <li...@ss...> - 2010-07-08 21:22:03
|
Hi Dave and Emily, > It sounds like the sensor Emily is using has a separate I/O voltage > for the i2c. It would be worth finding out which sensor this is, just > so that we can double check it. Whoops - Too much coffee - I read the sentence: "My device does have a special supply IO pin which..." as "My device does *not* have a special supply IO pin which..." My fault - Sorry and *thanks* for correcting me. In this case I think you should be clear to go. In case it isn't working I agree it's beginning to get kind of strange. I can't remember: Are the pin-muxing of I2C normally set correct in the standard Gumstix u-boot? Secondly: Can you measure any activity on the I2C lines when trying to access the sensors - Maybe you already stated this I can't remember... Third: As suggested by Dave: Can you share a little more about your setup - Sensor type, full schematics, etc. Sorry for not reading the post detailed enough and (@Dave) thanks again for catching my mistake :-) Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk |
From: batoub <ba...@gm...> - 2010-07-09 12:47:55
|
Hi everybody, I have a strange similar problem using i2c with the overo. I have ivero earth + summit + sensor SRF08. I use this level converter http://www.sparkfun.com/commerce/product_info.php?products_id=8745 Everything seems to be ok for SCL but SDA is not working at all. I try at 400khz, 100khz but when I try i2cdetect or i2cset SDA is always UP. Thanks for your answer ! |
From: Dave H. <dhy...@gm...> - 2010-07-09 15:34:10
|
Hi, On Fri, Jul 9, 2010 at 5:47 AM, batoub <ba...@gm...> wrote: > Hi everybody, > > I have a strange similar problem using i2c with the overo. > > I have ivero earth + summit + sensor SRF08. I use this level converter > http://www.sparkfun.com/commerce/product_info.php?products_id=8745 > > Everything seems to be ok for SCL but SDA is not working at all. I try at > 400khz, 100khz but when I try i2cdetect or i2cset SDA is always UP. If, in fact SDA is always high (a multimeter isn't good enough to check - you need a scope or a logic analyzer) then you've got a problem. With nothing connected to the summit, you should see SDA toggling if you do an i2cdetect -y -r 3 -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: Dustin H. <du...@ho...> - 2010-07-09 16:09:10
|
On Fri, Jul 9, 2010 at 11:33 AM, Dave Hylands <dhy...@gm...> wrote: > On Fri, Jul 9, 2010 at 5:47 AM, batoub <ba...@gm...> wrote: >> Hi everybody, >> I use this level converter >> http://www.sparkfun.com/commerce/product_info.php?products_id=8745 > With nothing connected to the summit, you should see SDA toggling if you do an > > i2cdetect -y -r 3 > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > Just in case: With this level converter, you have to use both TX lines for I2C, one TX line and one RX line won't cut it. The TX lines are bidirectional, and the RX lines are unidirectional. -- Dustin L. Howett |
From: emmers369 <emm...@ya...> - 2010-07-09 20:27:02
|
Hi Dave and Søren, Here are the data sheet for the Invensense ( http://invensense.com/mems/gyro/documents/PS-ITG-3200-00-01.4.pdf 3-axis gyro and the http://invensense.com/mems/gyro/documents/EB-ITG-3200-00-01.1.pdf eval board I am using. Let me know if there is anything you see that I am missing. Thanks, Emily Søren Steen Christensen wrote: > > Hi Dave and Emily, > >> It sounds like the sensor Emily is using has a separate I/O voltage >> for the i2c. It would be worth finding out which sensor this is, just >> so that we can double check it. > > Whoops - Too much coffee - I read the sentence: > "My device does have a special supply IO pin which..." > as > "My device does *not* have a special supply IO pin which..." > > My fault - Sorry and *thanks* for correcting me. In this case I think you > should be clear to go. > In case it isn't working I agree it's beginning to get kind of strange. > > I can't remember: Are the pin-muxing of I2C normally set correct in the > standard Gumstix u-boot? > > Secondly: Can you measure any activity on the I2C lines when trying to > access the sensors - Maybe you already stated this I can't remember... > > Third: As suggested by Dave: Can you share a little more about your setup > - > Sensor type, full schematics, etc. > > Sorry for not reading the post detailed enough and (@Dave) thanks again > for > catching my mistake :-) > Søren > > --- > SSC Solutions ApS - Denmark - www.ssc-solutions.dk > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29122101.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Dave H. <dhy...@gm...> - 2010-07-09 20:50:06
|
HI Emily, On Fri, Jul 9, 2010 at 1:26 PM, emmers369 <emm...@ya...> wrote: > > Hi Dave and Søren, > Here are the data sheet for the Invensense ( > http://invensense.com/mems/gyro/documents/PS-ITG-3200-00-01.4.pdf 3-axis > gyro and the > http://invensense.com/mems/gyro/documents/EB-ITG-3200-00-01.1.pdf eval board > I am using. Let me know if there is anything you see that I am missing. So which pin on which header are you using to supply the VLOGIC with 1.8v? There seems to be 2 VLOGIC signals on the eval board. It looks like M6 needs to be shorted (soldered) to connect the 2 VLOGICs together and get the pullups set properly. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ |
From: Søren S. C. <li...@ss...> - 2010-07-09 20:58:24
|
Hi Emily, Just gave it a quick view and have a couple of questions/comments 1) From where are you applying to clock to the eval-board (pin 1 to the chip)? 2) You have (of cause) measured that both VDD and V_LOGIC at the chip are as expected? 3) In Linux you are using I2C address 0x68 or 0x69 (depending on AD0) for communication? 4) You see actual communication on the I2C lines (from OMAP using an oscilloscope) but the chip NACKs the communication? If you can answer positive to the above questions I'm unfortunately currently out of ideas :-) Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk -----Original Message----- From: emmers369 [mailto:emm...@ya...] Sent: Friday, July 09, 2010 10:27 PM To: gum...@li... Subject: Re: [Gumstix-users] I2C troubles with Overo/Pinto Hi Dave and Søren, Here are the data sheet for the Invensense ( http://invensense.com/mems/gyro/documents/PS-ITG-3200-00-01.4.pdf 3-axis gyro and the http://invensense.com/mems/gyro/documents/EB-ITG-3200-00-01.1.pdf eval board I am using. Let me know if there is anything you see that I am missing. Thanks, Emily Søren Steen Christensen wrote: > > Hi Dave and Emily, > >> It sounds like the sensor Emily is using has a separate I/O voltage >> for the i2c. It would be worth finding out which sensor this is, just >> so that we can double check it. > > Whoops - Too much coffee - I read the sentence: > "My device does have a special supply IO pin which..." > as > "My device does *not* have a special supply IO pin which..." > > My fault - Sorry and *thanks* for correcting me. In this case I think you > should be clear to go. > In case it isn't working I agree it's beginning to get kind of strange. > > I can't remember: Are the pin-muxing of I2C normally set correct in the > standard Gumstix u-boot? > > Secondly: Can you measure any activity on the I2C lines when trying to > access the sensors - Maybe you already stated this I can't remember... > > Third: As suggested by Dave: Can you share a little more about your setup > - > Sensor type, full schematics, etc. > > Sorry for not reading the post detailed enough and (@Dave) thanks again > for > catching my mistake :-) > Søren > > --- > SSC Solutions ApS - Denmark - www.ssc-solutions.dk > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/I2C-troubles-with-Overo-Pinto-tp29098317p29122101.html Sent from the Gumstix mailing list archive at Nabble.com. ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |