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 the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/846799d8-d0bf-481a-9599-cd3b97c1b065%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
