From: Paul N. 2 <idr...@gm...> - 2011-10-16 09:36:58
|
I`ve spent over a year developing a GumStix based product. All I have to show for it is this: http://idruna.com/images/overo/Overos.JPG All of them died within 4 seconds to 4 days of being plugged into my custom board. When plugged into the Summit as a reference, with a working MicroSD card, the green power light comes on, but the blue light does not. No text on the terminal. The latest deaths have all been Sands, so no NAND. My designer, who has successfully produced similar boards in the past, has gone over my boards with a fine tooth comb and oscilloscope, and every single pin is within the GumStix specifications. I hired a 2nd highly experienced engineer to go over the board and he doesn't see anything that could kill an Overo either. The boards were professionally made and assembled by Sierra Circuits. Here is a link to the pins connected to the Overo: http://idruna.com/images/overo/OveroPins.JPG Our first thought was that USBH_VBUS was the problem. That line has since been cut, it doesn't appear to be needed. Our second thought, if unlikely, was that R9 and R13 should be changed to 1.8K to get the voltage at exactly 1.8V instead of 2.0V. No luck. Our third thought was confirmed by Don to be an Overo killer, and that was the 3.3V supply coming on for a short time when power is first applied before being turned off by the PIC. As there is no documentation on the minimum length of time the Overo must be powered on before it can be powered down, I changed the PIC firmware to simply leave 3.3V on at startup to eliminate this as a potential problem. Another day, another dead Overo. ADCIN2, OTG_VBUS, PWM1, PWM0, OTG_N, OTG_P, GPIO71, GPIO 70, GPIO 72, OLED_RES, OV_SDA, OV_SCL, OLED_DC go to headers or connectors that are not connected to anything at this stage. That leaves the following pins as the only ones connected: GND VSYSTEM - looks perfect on the scope. Supplied by an LT3971-3.3, connected to two protected 18650 batteries (7.2-8.4V). N_MANUAL_RESET - connected to PIC32 via resistor VBACKUP - connected to the PIC32's power supply GPIO166_IR_TXD3 - connected to a PIC32 via level shifter GPIO165_IR_RXD3 -- connected to a PIC32 via resistor GPIO148_TXD1 -- connected to a PIC32 via level shifter GPIO151_RXD1 -- connected to a PIC32 via resistor GPIO173_SPI1_MISO - connected to ADS7846IRGVR touch controller via level shifter GPIO172_SPI1_MOSI - same GPIO12_MMC3_CLK - same GPIO175_SPI1_CS1 - same GPIO114_SPI1_NIR Q- same USBH_DP - connected to USB2517 7 port hub USBH_DM - same Can anyone think of any possible way I could be killing all these Overos? Thanks, -- Paul Nolan, CEO Idruna Software Inc. -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32660989.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Giovanni C. <uc...@gm...> - 2011-10-16 15:43:49
|
Dear Paul, since July I am experiencing the same problems with my custom project: I connect a new Overo Fire on my custom made board and after a few days it stops working, sinking about 5 ampere from switching power supply: this way, I burned 3 overo fire extended, experiencing the same symptoms you have. I designed and assembled the custom board; each time I start working on it, I check that there are no short circuit between ground and all the supplies I have all around the board (3.7, 2.8, 1.8). As main power supply I used the 3.7V coming from lab switching power supply. When all the incident occurred, I saw that the 1.8V linear power supply was boiling hot, and after incident was not working anymore. For the execution of next tests, which I will experience until I burn my last two overo (and after I will stop it) I am going to use 3.7V coming directly from a li-ion battery, I will use solder paste stencil, in order to produce cleaner parts, and I will not connect any other peripherals (in fact, I burned also two gprs modem). Tomorrow I will post my overo connection schematic. The only difference I saw between main and your schematic, gpio apart, is I connected VBACKUP and AGND to ground. At the moment, total damages is about at 1000 euros, and I do not know who I could ask for support. Hope you will solve your problem. bye -g |
From: Steve S. <sa...@gm...> - 2011-10-16 17:36:03
|
On Sun, Oct 16, 2011 at 8:43 AM, Giovanni Casano <uc...@gm...> wrote: > Tomorrow I will post my overo connection schematic. The only difference I > saw between main and your schematic, gpio apart, is > I connected VBACKUP and AGND to ground. Probably not what is killing your Overos, but . . . VBACKUP is intended to provide battery backup power to the PMIC RTC circuit. It should either be left open or connected to a rechargeable lithium battery. When the system is powered up the PMIC attempts to trickle charge the battery. Hence tying this pin to ground is *not* a good idea! Steve > At the moment, total damages is about at 1000 euros, and I do not know who I > could ask for support. > Hope you will solve your problem. > bye > -g > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2d-oct > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > |
From: Casano G. <uc...@gm...> - 2011-10-16 19:44:44
|
This time, every little piece could save the world... Tomorrow i will cut gnd connection from vbackup and will give it a try. -g Il giorno 16/ott/2011, alle ore 19:35, Steve Sakoman <sa...@gm...> ha scritto: > On Sun, Oct 16, 2011 at 8:43 AM, Giovanni Casano <uc...@gm...> wrote: > >> Tomorrow I will post my overo connection schematic. The only difference I >> saw between main and your schematic, gpio apart, is >> I connected VBACKUP and AGND to ground. > > Probably not what is killing your Overos, but . . . > > VBACKUP is intended to provide battery backup power to the PMIC RTC > circuit. It should either be left open or connected to a rechargeable > lithium battery. When the system is powered up the PMIC attempts to > trickle charge the battery. Hence tying this pin to ground is *not* a > good idea! > > Steve > >> At the moment, total damages is about at 1000 euros, and I do not know who I >> could ask for support. >> Hope you will solve your problem. >> bye >> -g >> >> ------------------------------------------------------------------------------ >> All the data continuously generated in your IT infrastructure contains a >> definitive record of customers, application performance, security >> threats, fraudulent activity and more. Splunk takes this data and makes >> sense of it. Business sense. IT sense. Common sense. >> http://p.sf.net/sfu/splunk-d2d-oct >> _______________________________________________ >> gumstix-users mailing list >> gum...@li... >> https://lists.sourceforge.net/lists/listinfo/gumstix-users >> >> > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2d-oct > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Paul N. <idr...@gm...> - 2011-10-17 02:01:19
|
> > VBACKUP is intended to provide battery backup power to the PMIC RTC > circuit. It should either be left open or connected to a rechargeable > lithium battery. When the system is powered up the PMIC attempts to > trickle charge the battery. Hence tying this pin to ground is *not* a > good idea Steve, could connecting VBACKUP the way my board does it cause this kind of damage? |
From: Paul N. <idr...@gm...> - 2011-10-17 02:14:27
|
> > When all the incident occurred, I saw that the 1.8V linear power supply was > boiling hot, and after incident was not working anymore. > > How is your 1.8V supply connected? > > Tomorrow I will post my overo connection schematic. The only difference I > saw between main and your schematic, gpio apart, is > I connected VBACKUP and AGND to ground. > > At the moment, total damages is about at 1000 euros, and I do not know who > I could ask for support. > > Hope you will solve your problem. > Good luck, post back if you figure your problem out! |
From: Giovanni C <uc...@gm...> - 2011-10-17 07:44:48
|
attached below you will find two schematics: the first will show the 1V8 and 2V8 linear power supply connection; the second will show the connection to the Overo Gumstix. Note 1: I used TI TXS0104 for bidirectional level translator; Note 2: each power supply is filtered with two caps and one ferrite bead (I am really afraid of the noise). Any suggestions are kindly appreciated. > Good luck, post back if you figure your problem out! > I'll do it. http://old.nabble.com/file/p32665097/proc.png proc.png http://old.nabble.com/file/p32665097/alim2.png alim2.png -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32665097.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Paul N. <pa...@ca...> - 2011-10-17 08:52:21
|
> Any suggestions are kindly appreciated. I`m a software guy so I`m probably missing something, but how come the pins on the 70 pin connectors are in different places to mine? USBH_DM is at the bottom of the connector on mine. -- Paul Nolan, CEO Idruna Software Inc. |
From: Giovanni C <uc...@gm...> - 2011-10-17 09:09:14
|
I followed the scheme reported at http://www.gumstix.org/hardware-design/overo-coms/74-overo-connectors/100-gumstix-overo-coms-70-pin-connector-j4-features-extended-memory-bus-and-mmc-signals.html consider that, in my schematic, J4 connector pins are translated of +70. So, for example, pin number 105 on my schematc is pin number (105-70=)35 on real OVERO J4 connector. Thanks! -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32665525.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Paul N. <pa...@ca...> - 2011-10-17 09:48:44
|
> consider that, in my schematic, J4 connector pins are translated of +70. So, > for example, pin number > 105 on my schematc is pin number (105-70=)35 on real OVERO J4 connector. Shouldn't the pins still be in the same physical place relative to each other though? Looking at J4, the bottom pins should be USBH_DM and GPIO19_MMC3_D1, on yours it is GPIO19 and GPIO23? -- Paul Nolan, CEO Idruna Software Inc. |
From: Giovanni C <uc...@gm...> - 2011-10-17 15:25:46
|
Paul, if you have any news, please do not hesitate to post! -g -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32668045.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Giovanni C <uc...@gm...> - 2011-10-17 10:11:03
|
You are right, it is a schematic notation problem... I will attach the J4 land pattern to present reply: it should be fine... or, anyway, no short circuit between Vcc-GND ;) could be a case? http://old.nabble.com/file/p32665850/J4-land.png J4-land.png Paul Nolan wrote: > > Shouldn't the pins still be in the same physical place relative to each > other though? Looking at J4, the bottom pins should be USBH_DM and > GPIO19_MMC3_D1, on yours it is GPIO19 and GPIO23? > -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32665850.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Steve S. <sa...@gm...> - 2011-10-17 13:55:31
|
On Sun, Oct 16, 2011 at 7:01 PM, Paul Nolan <idr...@gm...> wrote: >> >> >> VBACKUP is intended to provide battery backup power to the PMIC RTC >> circuit. It should either be left open or connected to a rechargeable >> lithium battery. When the system is powered up the PMIC attempts to >> trickle charge the battery. Hence tying this pin to ground is *not* a >> good idea > > Steve, could connecting VBACKUP the way my board does it cause this kind > of damage? I don't think so. I'd just remove the resistor. Not sure what your issue is, but I didn't really spend to much time looking at the schematic (just a quick glance for anything really obvious). Steve |
From: Paul N. 2 <idr...@gm...> - 2011-10-17 19:37:26
|
sakoman wrote: > > I don't think so. I'd just remove the resistor. > > Not sure what your issue is, but I didn't really spend to much time > looking at the schematic (just a quick glance for anything really > obvious). > > Steve > Can you email me a quote for a detailed look please? Paul Nolan, CEO Idruna Software Inc. -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32669942.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Paul N. 2 <idr...@gm...> - 2011-10-17 19:58:02
|
Giovanni C wrote: > > You are right, it is a schematic notation problem... I will attach the J4 > land pattern to present reply: > it should be fine... or, anyway, no short circuit between Vcc-GND ;) could > be a case? > > http://old.nabble.com/file/p32665850/J4-land.png J4-land.png > Can't see anything I`m afraid, schematics is a little out of my area of expertise. Have you put the 1.8V and 3.7V line on a scope to make sure there are no surges when powering up and down? Only other thing I can think of is that my engineer advised me a while back that problems are much easier to spot if you use the same notation as the reference design. -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32670117.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: Giovanni C <uc...@gm...> - 2011-10-19 08:51:23
|
Paul Nolan 2 wrote: > > Can't see anything I`m afraid, schematics is a little out of my area of > expertise. Have you put the 1.8V and 3.7V line on a scope to make sure > there are no surges when powering up and down? > 1,8V and 2,8V come from linear power supply, the 1,8V is the one suggested in gumstix tobi schematics. > Only other thing I can think of is that my engineer advised me a while > back that problems are much easier to spot if you use the same notation as > the reference design. > Yes, this would be better, maybe for the next designs... -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32680794.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: David V. <dve...@ta...> - 2011-10-18 16:41:22
|
> > > Paul, if you have any news, please do not hesitate to post! > -g > What do you have the analog channels tied to? They are not allowed to go above 2.5v ..and should be resistor scaled. DV |
From: Giovanni C <uc...@gm...> - 2011-10-19 08:54:56
|
Analog are resistor scaled up to 2,5V. Aux line input comes from a microphone preamplifier, which gives out Line Level Audio signals. -g David Vescovi-2 wrote: > > What do you have the analog channels tied to? > > They are not allowed to go above 2.5v ..and should be resistor scaled. > -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32680816.html Sent from the Gumstix mailing list archive at Nabble.com. |
From: R. P. M. <log...@gm...> - 2011-10-19 10:01:56
|
I have this experience with killing an Overo board:- 1) Using a PSU plugged into the mains supply, and 2) Using an Earth plugged into a Summit, and 3) Using a laptop plugged into the Summit USB, and 4) The laptop charger is plugged into a different mains socket. With all these four things together the Earth board died and was unable to communicate on the UART3 port. I traced the problem the the different mains phases used for the laptop charger and the 5.0V PSU plugged into the Summit. While in theory both the laptop charger and the 5.0V PSU are isolated supplies there is still a small amount of leakage voltage and/or charge that seems able to cross the isolation barrier and create an AC voltage potential difference between the two systems. I was able to measure the open circuit voltage as ~420VAC with a multimeter between the two grounds of the Summit-to-PC USB connection. RP On 10/16/11, Paul Nolan 2 <idr...@gm...> wrote: > > I`ve spent over a year developing a GumStix based product. All I have to > show for it is this: > http://idruna.com/images/overo/Overos.JPG > > All of them died within 4 seconds to 4 days of being plugged into my custom > board. When plugged into the Summit as a reference, with a working MicroSD > card, the green power light comes on, but the blue light does not. No text > on the terminal. The latest deaths have all been Sands, so no NAND. > > My designer, who has successfully produced similar boards in the past, has > gone over my boards with a fine tooth comb and oscilloscope, and every > single pin is within the GumStix specifications. I hired a 2nd highly > experienced engineer to go over the board and he doesn't see anything that > could kill an Overo either. The boards were professionally made and > assembled by Sierra Circuits. > > Here is a link to the pins connected to the Overo: > http://idruna.com/images/overo/OveroPins.JPG > > Our first thought was that USBH_VBUS was the problem. That line has since > been cut, it doesn't appear to be needed. > Our second thought, if unlikely, was that R9 and R13 should be changed to > 1.8K to get the voltage at exactly 1.8V instead of 2.0V. No luck. > Our third thought was confirmed by Don to be an Overo killer, and that was > the 3.3V supply coming on for a short time when power is first applied > before being turned off by the PIC. As there is no documentation on the > minimum length of time the Overo must be powered on before it can be powered > down, I changed the PIC firmware to simply leave 3.3V on at startup to > eliminate this as a potential problem. Another day, another dead Overo. > > ADCIN2, OTG_VBUS, PWM1, PWM0, OTG_N, OTG_P, GPIO71, GPIO 70, GPIO 72, > OLED_RES, OV_SDA, OV_SCL, OLED_DC go to headers or connectors that are not > connected to anything at this stage. > > That leaves the following pins as the only ones connected: > > GND > VSYSTEM - looks perfect on the scope. Supplied by an LT3971-3.3, connected > to two protected 18650 batteries (7.2-8.4V). > N_MANUAL_RESET - connected to PIC32 via resistor > VBACKUP - connected to the PIC32's power supply > GPIO166_IR_TXD3 - connected to a PIC32 via level shifter > GPIO165_IR_RXD3 -- connected to a PIC32 via resistor > GPIO148_TXD1 -- connected to a PIC32 via level shifter > GPIO151_RXD1 -- connected to a PIC32 via resistor > > GPIO173_SPI1_MISO - connected to ADS7846IRGVR touch controller via level > shifter > GPIO172_SPI1_MOSI - same > GPIO12_MMC3_CLK - same > GPIO175_SPI1_CS1 - same > GPIO114_SPI1_NIR Q- same > > USBH_DP - connected to USB2517 7 port hub > USBH_DM - same > > Can anyone think of any possible way I could be killing all these Overos? > > Thanks, > -- > Paul Nolan, CEO Idruna Software Inc. > > -- > View this message in context: > http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32660989.html > Sent from the Gumstix mailing list archive at Nabble.com. > > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2d-oct > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Clifford H. <cli...@gm...> - 2011-10-19 11:18:21
|
On 19/10/2011, at 9:01 PM, R. P. McMurphy wrote: > I have this experience with killing an Overo board:- > > 1) Using a PSU plugged into the mains supply, and > … > I was able to measure > the open circuit voltage as ~420VAC with a multimeter between the two > grounds of the Summit-to-PC USB connection. Ouch. Funnily enough, a friend reported getting small sparks and unpleasant tingles from a powered USB hub when connecting it to his laptop. Same reason, as I explained to him. No idea what the regulatory authorities have to say about the allowed amount of capacitive coupling - but Australia at least has just banned sale of transformer- based plug-packs, so there's less reason for coupling with new gear. Doesn't mean that the new gear is better, of course. Clifford Heath. > > RP > > On 10/16/11, Paul Nolan 2 <idr...@gm...> wrote: >> >> I`ve spent over a year developing a GumStix based product. All I have to >> show for it is this: >> http://idruna.com/images/overo/Overos.JPG >> >> All of them died within 4 seconds to 4 days of being plugged into my custom >> board. When plugged into the Summit as a reference, with a working MicroSD >> card, the green power light comes on, but the blue light does not. No text >> on the terminal. The latest deaths have all been Sands, so no NAND. >> >> My designer, who has successfully produced similar boards in the past, has >> gone over my boards with a fine tooth comb and oscilloscope, and every >> single pin is within the GumStix specifications. I hired a 2nd highly >> experienced engineer to go over the board and he doesn't see anything that >> could kill an Overo either. The boards were professionally made and >> assembled by Sierra Circuits. >> >> Here is a link to the pins connected to the Overo: >> http://idruna.com/images/overo/OveroPins.JPG >> >> Our first thought was that USBH_VBUS was the problem. That line has since >> been cut, it doesn't appear to be needed. >> Our second thought, if unlikely, was that R9 and R13 should be changed to >> 1.8K to get the voltage at exactly 1.8V instead of 2.0V. No luck. >> Our third thought was confirmed by Don to be an Overo killer, and that was >> the 3.3V supply coming on for a short time when power is first applied >> before being turned off by the PIC. As there is no documentation on the >> minimum length of time the Overo must be powered on before it can be powered >> down, I changed the PIC firmware to simply leave 3.3V on at startup to >> eliminate this as a potential problem. Another day, another dead Overo. >> >> ADCIN2, OTG_VBUS, PWM1, PWM0, OTG_N, OTG_P, GPIO71, GPIO 70, GPIO 72, >> OLED_RES, OV_SDA, OV_SCL, OLED_DC go to headers or connectors that are not >> connected to anything at this stage. >> >> That leaves the following pins as the only ones connected: >> >> GND >> VSYSTEM - looks perfect on the scope. Supplied by an LT3971-3.3, connected >> to two protected 18650 batteries (7.2-8.4V). >> N_MANUAL_RESET - connected to PIC32 via resistor >> VBACKUP - connected to the PIC32's power supply >> GPIO166_IR_TXD3 - connected to a PIC32 via level shifter >> GPIO165_IR_RXD3 -- connected to a PIC32 via resistor >> GPIO148_TXD1 -- connected to a PIC32 via level shifter >> GPIO151_RXD1 -- connected to a PIC32 via resistor >> >> GPIO173_SPI1_MISO - connected to ADS7846IRGVR touch controller via level >> shifter >> GPIO172_SPI1_MOSI - same >> GPIO12_MMC3_CLK - same >> GPIO175_SPI1_CS1 - same >> GPIO114_SPI1_NIR Q- same >> >> USBH_DP - connected to USB2517 7 port hub >> USBH_DM - same >> >> Can anyone think of any possible way I could be killing all these Overos? >> >> Thanks, >> -- >> Paul Nolan, CEO Idruna Software Inc. >> >> -- >> View this message in context: >> http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32660989.html >> Sent from the Gumstix mailing list archive at Nabble.com. >> >> >> ------------------------------------------------------------------------------ >> All the data continuously generated in your IT infrastructure contains a >> definitive record of customers, application performance, security >> threats, fraudulent activity and more. Splunk takes this data and makes >> sense of it. Business sense. IT sense. Common sense. >> http://p.sf.net/sfu/splunk-d2d-oct >> _______________________________________________ >> gumstix-users mailing list >> gum...@li... >> https://lists.sourceforge.net/lists/listinfo/gumstix-users >> > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2d-oct > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Alex G. <al...@al...> - 2011-10-19 22:57:17
|
On 19/10/2011 10:18 PM, Clifford Heath wrote: > On 19/10/2011, at 9:01 PM, R. P. McMurphy wrote: >> I have this experience with killing an Overo board:- >> >> 1) Using a PSU plugged into the mains supply, and >> … >> I was able to measure >> the open circuit voltage as ~420VAC with a multimeter between the two >> grounds of the Summit-to-PC USB connection. > > > Ouch. Funnily enough, a friend reported getting small sparks and unpleasant > tingles from a powered USB hub when connecting it to his laptop. Same > reason, as I explained to him. > > No idea what the regulatory authorities have to say about the allowed amount > of capacitive coupling - but Australia at least has just banned sale of transformer- > based plug-packs, so there's less reason for coupling with new gear. Doesn't > mean that the new gear is better, of course. > > Clifford Heath. > Be nice if optocoupled usb isolators were cheaper but can get them for around US$300 (still to expensive to get my boss to get one) note I haven't tried these myself http://www.kvms.com/Product/SP380A.aspx maxim has a tech note using HCPL-2531 optocouplers http://www.maxim-ic.com/app-notes/index.mvp/id/3891 Haven't had the time to give it a try myself. These troubles are only going to get worse as io voltages decrease. Alex |
From: William P. S. I. <bil...@xp...> - 2011-10-20 00:02:02
|
Hi All; Not sure if this will work where you folks are, because in Canada we have 117 VRMS mains ... That said. I have made a couple of isolation transformers for customers with ground loop problems. I assume that a 220-240 volt version is also available from Hammond. Also I know it sounds trite, but why don't you use a battery and a linear regulator ? I know it's a pain in the ass, but it's a lot cheaper that 10 Overo's :-( Bill "People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." - George Orwell -----Original Message----- From: Alex Gibson [mailto:al...@al...] Sent: Wednesday, October 19, 2011 6:57 PM To: General mailing list for gumstix users. Subject: Re: [Gumstix-users] How have I managed to kill 10 Overos? On 19/10/2011 10:18 PM, Clifford Heath wrote: > On 19/10/2011, at 9:01 PM, R. P. McMurphy wrote: >> I have this experience with killing an Overo board:- >> >> 1) Using a PSU plugged into the mains supply, and >> . >> I was able to measure >> the open circuit voltage as ~420VAC with a multimeter between the two >> grounds of the Summit-to-PC USB connection. > > > Ouch. Funnily enough, a friend reported getting small sparks and unpleasant > tingles from a powered USB hub when connecting it to his laptop. Same > reason, as I explained to him. > > No idea what the regulatory authorities have to say about the allowed amount > of capacitive coupling - but Australia at least has just banned sale of transformer- > based plug-packs, so there's less reason for coupling with new gear. Doesn't > mean that the new gear is better, of course. > > Clifford Heath. > Be nice if optocoupled usb isolators were cheaper but can get them for around US$300 (still to expensive to get my boss to get one) note I haven't tried these myself http://www.kvms.com/Product/SP380A.aspx maxim has a tech note using HCPL-2531 optocouplers http://www.maxim-ic.com/app-notes/index.mvp/id/3891 Haven't had the time to give it a try myself. These troubles are only going to get worse as io voltages decrease. Alex ---------------------------------------------------------------------------- -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Ciosco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Paul N. <idr...@gm...> - 2011-10-21 09:44:19
|
On Wed, Oct 19, 2011 at 5:01 PM, William Pretty Security Inc < bil...@xp...> wrote: > > Also I know it sounds trite, but why don't you use a battery and a linear > regulator ? > I know it's a pain in the ass, but it's a lot cheaper that 10 Overo's :-( > > Bill > Make that 11. I`m testing a linear regulator now, but it gets too hot to use for more than a short time (system is powered by two 18650 batteries in series, so 7.2-8.4V). My other test was to add a super cap to the 3.3V switching regulator. Worked fine for over 100 battery insertions. The next day I inserted the battery and the Overo died, to the sound of much cursing. I`ve tested the voltage on an oscilloscope, and the voltage goes up in a straight line with no overshoot when the battery is inserted. The TPS chip on the Overo is supposed to be able to handle up to 4.2V and spikes up to 5.2V, so I have no idea what can be causing my problems. If I don't' have a solution by Monday I`ll have no choice but to switch to a COM supplier that offers technical support such as schematic review services etc. |
From: Jerry W. <who...@ya...> - 2011-10-21 12:49:38
|
Speaking of schematic review, post the schematics of everything from the battery up to where it connects to the overo. I just finished a project using the 18650 batteries and its going just fine. But then again, I'm only using 1 battery and a boost mode supply. ________________________________ From: Paul Nolan <idr...@gm...> To: General mailing list for gumstix users. <gum...@li...> Sent: Friday, October 21, 2011 5:44 AM Subject: Re: [Gumstix-users] How have I managed to kill 10 Overos? On Wed, Oct 19, 2011 at 5:01 PM, William Pretty Security Inc <bil...@xp...> wrote: Also I know it sounds trite, but why don't you use a battery and a linear >regulator ? >I know it's a pain in the ass, but it's a lot cheaper that 10 Overo's :-( > >Bill > Make that 11. I`m testing a linear regulator now, but it gets too hot to use for more than a short time (system is powered by two 18650 batteries in series, so 7.2-8.4V). My other test was to add a super cap to the 3.3V switching regulator. Worked fine for over 100 battery insertions. The next day I inserted the battery and the Overo died, to the sound of much cursing. I`ve tested the voltage on an oscilloscope, and the voltage goes up in a straight line with no overshoot when the battery is inserted. The TPS chip on the Overo is supposed to be able to handle up to 4.2V and spikes up to 5.2V, so I have no idea what can be causing my problems. If I don't' have a solution by Monday I`ll have no choice but to switch to a COM supplier that offers technical support such as schematic review services etc. ------------------------------------------------------------------------------ The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: William P. S. I. <bil...@xp...> - 2011-10-21 18:16:33
|
Try this Digikey part: 78ST205HC-ND Just follow the information on the data sheet and you can't go wrong J As for schematic review services, I can probably do that for you, and I would always tell you up front if I didn't feel qualified. Before billing you. (I have really good rates for R&D.) If there is enough demand, I may considering offering some basic boards like universal supplies USB adapter boards with power supplies and what not, on EBay. "People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." - George Orwell From: Paul Nolan [mailto:idr...@gm...] Sent: Friday, October 21, 2011 5:44 AM To: General mailing list for gumstix users. Subject: Re: [Gumstix-users] How have I managed to kill 10 Overos? On Wed, Oct 19, 2011 at 5:01 PM, William Pretty Security Inc <bil...@xp...> wrote: Also I know it sounds trite, but why don't you use a battery and a linear regulator ? I know it's a pain in the ass, but it's a lot cheaper that 10 Overo's :-( Bill Make that 11. I`m testing a linear regulator now, but it gets too hot to use for more than a short time (system is powered by two 18650 batteries in series, so 7.2-8.4V). My other test was to add a super cap to the 3.3V switching regulator. Worked fine for over 100 battery insertions. The next day I inserted the battery and the Overo died, to the sound of much cursing. I`ve tested the voltage on an oscilloscope, and the voltage goes up in a straight line with no overshoot when the battery is inserted. The TPS chip on the Overo is supposed to be able to handle up to 4.2V and spikes up to 5.2V, so I have no idea what can be causing my problems. If I don't' have a solution by Monday I`ll have no choice but to switch to a COM supplier that offers technical support such as schematic review services etc. |