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!
I, too, am interested to know this. Wondering what the nominal and max. voltages are for SYS VIN and BAT VIN. Also, what sort of temperature sensor gets hooked up to BAT TEMP.
– Will
P2 pins 14 and 16 ?
Pin 14 is the positive input for a single cell lithium (lion/lipo) battery. Data sheet lists max input of 7V so you could use other battery combinations/chemistries if you like, but the internal circuitry will protect based on a single cell lithium.
Pin 16 is for a temperature sensor used for battery charging. From the data sheet:
Temperature sense input. Connect to NTC thermistor to sense battery temperature. Works with 10k and 100k thermistors.
I attached a snapshot showing the battery charge/temp sense circuit.
Adam –
Great, thanks for the info!
BTW, would you provide a link to the data sheet?
– Will
Thank you very much! The voltage limit was a concern.
- Shannon
From: ajsaenz@gmail.com
Sent: November 10, 2017 12:54 PM
To: beagleboard@googlegroups.com
Reply-to: beagleboard@googlegroups.com
Subject: [beagleboard] Re: battery power for PocketBeagle?
|
- |
Pin 14 is the positive input for a single cell lithium (lion/lipo) battery. Data sheet lists max input of 7V so you could use other battery combinations/chemistries if you like, but the internal circuitry will protect based on a single cell lithium.
Pin 16 is for a temperature sensor used for battery charging. From the data sheet:
Temperature sense input. Connect to NTC thermistor to sense battery temperature. Works with 10k and 100k thermistors.
I attached a snapshot showing the battery charge/temp sense circuit.
Keep in mind that the 7V is Absolute Max voltage so you should operate below this level or risk damaging the chip.
Here is the link to data sheet: http://www.ti.com/lit/ds/symlink/tps65217.pdf
Remember that this TI power management IC is integrated into the Octavo Systems part so that is why the data sheet is from TI.
Adam
Adam --
This data sheet will be very useful. Thanks for sharing it!
Sincerely,
-- Will
So if I connect Vbat (LiPo) to pin 14 I should expect the PocketBeagle to run, shouldn’t I? (And obviously connect GND.)
With the PocketBeagle I have nothing happens. (I even put a 10k resistor as a mock NTC.)
Yes, Pin 14 of the P2 Header. If you connect to Pin 14 of the P1 header you could have damaged your chip; that pin is connected to the 3.3V bus.
See section 7 (7.1.2 specifically) of the reference manual linked below.
https://github.com/beagleboard/pocketbeagle/wiki/System-Reference-Manual#Figure_24_PocketBeagle_Expansion_Headers
That’s exactly what I did. (And I’m certain I didn’t mix up P1 and P2.) I checked everything about ten times - there’s not much to do: One battery, two pins…
But nothing happens.
Does this work for you??
I just tried this and it works for me.
Battery plus to P2.14 and gnd to P2.15 (make sure you don’t use P2.16, that’s not batt gnd it’s temp sensor input).
Press power button on board and it starts (it does not auto boot like when connecting to USB).
Where did your 10k resistor go (P2.16 and gnd)?
The board draw about 300mA at 3.8V when I tried it.
Oh I see… I thought I tried with the push button, but apparently I didn’t. Yes, that works!
So, when pushed, the power button connects T11 on the SiM to GND. T11 is PB_IN of the TPS65127. PB_IN is the push button monitor (§8.3.3 of the datasheet rev. J):
“The push-button monitor has two functions. The first is to power-up the device from the OFF or SLEEP state when a falling edge is detected on the PB_IN pin. The second is to power cycle the device when the PB_IN pin is held low for more than 8 s.”
I see up to 300mA draw when booting, then about 200mA when idling.
Here is something that might help for all of you battery powering your devices:
http://derekmolloy.ie/changing-the-beaglebone-cpu-frequency/
I’ve effectively reduced power consumption to ~80 milliamps by slowing the cpu down to 300 MHz.
Naturally, you have to understand your situation. I don’t need high speed calculation or display - just moderate data crunching and large filesystem access.
thanks, all, for the great feedback from my original question.
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!)
I will test the serial connection first with just a micro USB charging cable rather than USB to a computer. (Simplify!)
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.)
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?
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).
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
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
Maybe I need more than 10uf. It runs just long enough for only a few lines on the serial console.
1F 5.5v supercap helps.
I’ll solder up the circuit with better current-carrying capacity.
Maybe I’ll set up one of my other pocket beagles with scaled op-amp inputs with 4051 and op amp. Some day?
“1F 5.5v supercap helps”
Curious, Fred, how long does it run on that supercap? more than a “few lines on the serial console?”
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 NTC Thermistor Temperature Sensors Provide Li-Ion Battery Safety | Ametherm.
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.