I am looking for 10K NTC Thermistors with B=3480. How critical is the B value, or what range can I accept? Currently I am looking on Mouser.
Is there a specific or recommended battery pack? I'm just using an 18650 from a local surplus store. Regarding the log file, I still need to do this: sudo /opt/scripts/tools/developers/update_bootloader.sh I'll also look for 100K thermistor with B=3960 On Thursday, August 30, 2018 at 5:35:43 PM UTC-7, Fred Kerr wrote: > > It runs well with the soldered implementation. My breadboards are a little > cheap. > > The attached minicom_20180830b.cap shows a boot with microUSB power from a > wall wart (from my rpi3), then a boot with the battery circuit. I left both > RX and TX attached; I'll play with disconnecting them another time. > > I'll look into getting some "telemetry" info from the pocket beagle. I'm > open to suggestions about things to add/log, etc. Also, I think this pocket > beagle doesn't have a fix that I got before - after the shutdown, things > panic. > > If anything else jumps out from the log file, please let me know! > > On Wednesday, August 29, 2018 at 10:59:03 AM UTC-7, Fred Kerr wrote: >> >> I'll try again soon with my more stable circuit (*soldered), also with RX >> disconnected so I just get output from the Pocket Beagle and the only power >> input is from the battery circuit. >> >> (*Soldered, so no loose breadboard connections, better current carrying >> capacity, etc.) >> >> What is a good way to share log files? Mine can get verbose! I could >> store it somewhere and post a link - suggestions welcomed! I have a lot of >> possibilities, but just let me know what works best for you. >> >> On Tuesday, August 28, 2018 at 12:51:23 PM UTC-7, Fred Kerr wrote: >>> >>> Yes, it ran quite a lot longer on the 1F, but still hung. >>> >>> I wired this up (see pic) to be more stable than the breadboard mess I >>> had. The led on 1.8k resistor is gonna run a lot longer than I'll take at >>> lunch!!! >>> >>> Can I isolate RX and TX or...oh I just need TX from the beagle for >>> visibility! >>> >>> 1F 5.5v supercap (that battery was discharged to 3.96v). This one has >>> more charge. Also put a 1000uf electrolytic on the soldered version, >>> "because". >>> >>> Fred Kerr (mobile) >>> >>> On Tue, Aug 28, 2018, 12:13 PM Jason Kridner <jkrid...@gmail.com> wrote: >>> >>>> >>>> >>>> On Monday, August 27, 2018 at 11:15:36 PM UTC-4, Fred Kerr wrote: >>>>> >>>>> Hello all, >>>>> >>>>> I'm being just a little bit careful here: >>>>> >>>>> I'm about to try this, but I will connect up the serial terminal >>>>> first, so I can see output and interact with the board. (Graceful >>>>> shutdown!) >>>>> >>>> >>>> Don't connect the power or RX (ie., serial cable to PocketBeagle) >>>> signals to avoid them interfering. Great thing to monitor. >>>> >>>> >>>>> >>>>> I will test the serial connection first with just a micro USB charging >>>>> cable rather than USB to a computer. (Simplify!) >>>>> >>>> >>>> Not sure what you are testing here. Are you just saying you'll power >>>> via the microUSB connection and not connect to a computer, just to see the >>>> behavior? You are monitoring with a serial connection? >>>> >>>> >>>>> >>>>> It's my understanding that LiPo charging is disabled or not present in >>>>> the firmware. (I'll give you the "uname -a" and other info the next time >>>>> I >>>>> fire it up. Just let me know what and how to check.) >>>>> >>>> >>>> It is not enabled by default. There is a flag in the PMIC that needs to >>>> be enabled. We've been playing with a driver to set the flag, but there >>>> are >>>> other bugs in that driver not related to actually charging. >>>> >>>> >>>>> >>>>> Also, it's not clear (without reading the data sheet :) ) about the >>>>> resistor values for the thermistor and the parallel (linearizing?) >>>>> resistor. >>>>> >>>>> If you have a 10K thermistor, do you put it in parallel with a 10K >>>>> resistor, or likewise 100K thermistor in parallel with a 100K resistor? >>>>> Do >>>>> you put the thermistor anywhere in contact with the (e.g., 18650) LiPo? >>>>> >>>> >>>> Looking at the TPS65217 datasheet says to put a 75kohm resistor in >>>> parallel. >>>> >>>> I'm not sure, but I believe the actual thermal resistor should be >>>> something like >>>> https://www.ametherm.com/blog/thermistors/thermistors-ntc-thermistor-temperature-sensors-provide-li-ion-battery-safety/ >>>> . >>>> >>>> >>>>> >>>>> From the prior thread, it seems to be sufficient (if even necessary) >>>>> just to connect a 10K resistor from TS (P2-16) to ground (P2-15). >>>>> >>>> >>>> Yes, that is supposed to work, ignoring the battery temperature. >>>> >>>> >>>>> >>>>> 10uF cap from battery (P2-14) to ground (P2-15). >>>>> >>>>> (Tangent/future: What about larger cap, perhaps using a 5.5V supercap, >>>>> detect supercap discharging (lipo voltage to ~min input voltage on vbat) >>>>> and give an interrupt to shut the board down?) >>>>> >>>>> >>>>> Thanks in advance for your help, and to the original thread authors! >>>>> >>>>> >>>>> Other posts that I found: >>>>> >>>>> Safely power down the PocketBeagle supplied by a battery (no replies?): >>>>> https://groups.google.com/d/msg/beagleboard/dDSD89DGzpU/j2WzZyA2CgAJ >>>>> >>>> >>>> I threw in a reply. >>>> >>>> >>>>> >>>>> >>>>> Supplying two ICs from the PocketBeagle powered by a Lipo battery >>>>> https://groups.google.com/d/msg/beagleboard/B7Zyf97hvzY/z8cOt0MHBwAJ >>>>> >>>>> I want to do some excessive self-telemetry, both internal and >>>>> external. I plan to scale the raw battery voltage by 1/11 with an op amp >>>>> before feeding to one of the 1.8V ADC inputs. I'll defer to suggestions >>>>> about measuring current. >>>>> >>>>> (This is a tangent: I also plan to be paranoid if I connect to a car >>>>> and want to monitor the car's "12V" with something like a VCO on the car >>>>> side pulsing to an optoisolator, but I'm sure there are better ideas out >>>>> there! :) (I could use several PIC -> nrf24l01 for some "really good" >>>>> isolation!) >>>>> >>>>> Thanks, >>>>> Fred Kerr >>>>> >>>>> On Friday, November 10, 2017 at 10:32:46 AM UTC-8, Adam Saenz wrote: >>>>>> >>>>>> Keep in mind that the 7V is Absolute Max voltage so you should >>>>>> operate below this level or risk damaging the chip. >>>>>> >>>>>> >>>>>> >>>>>> On Thursday, November 9, 2017 at 10:15:05 PM UTC-8, Shannon Mackey >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> I expect I'm overlooking something, But it isn't obvious to me how >>>>>>> to power the PocketBeagle with batteries. It doesn't have a similar >>>>>>> arrangement to BBB. Can someone point me in the right direction, >>>>>>> please? >>>>>>> Thanks! >>>>>>> >>>>>>> -- >>>> For more options, visit http://beagleboard.org/discuss >>>> --- >>>> You received this message because you are subscribed to a topic in the >>>> Google Groups "BeagleBoard" group. >>>> To unsubscribe from this topic, visit >>>> https://groups.google.com/d/topic/beagleboard/PQCNhmeBK3M/unsubscribe. >>>> To unsubscribe from this group and all its topics, send an email to >>>> beagleboard+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/beagleboard/846799d8-d0bf-481a-9599-cd3b97c1b065%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/beagleboard/846799d8-d0bf-481a-9599-cd3b97c1b065%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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