Thanks for the swift reply. Although it is a bit disappointing.
I am not that much worried about the display though. My major concern is that power management. I am wondering at the moment how this issue is being handled in a simple Amazon Kindle device? AFAIK it is Unix/Linux/Android based (not exactly sure) using 800MHz i.MX ARM processor and able to run for a whole month without recharging. Of course ever XX minutes it goes into deep sleep somehow. I will most probably continue the research with something like this, although the Omega was much more appealing with its 9$ price tag :)
Anyway ... thanks again for the reply and the involvement.
@cas said in Omega2+ losing power / powering off unexpectedly:
The pin pad underneath: <photo>
"Thermal pad is connected to GND layer through vias (recommend 4X4 pins and the aperture is 10mil)." /active-semi/
These holes are (thermal conducting) vias between the top and the bottom copper layers of the PCB.
The bottom of the dock was very hot to the touch, so I suspect I burnt out the ACT2801 which appears to have a pin pad underneath. Actually upon closer inspection of the pin pad, one if the holes appears to be blocked with a silver substance and I can't help wondering if that's solder (if that's at all possible).
Spot the mistake.... ;-)
It's a "perfect" solder material "bead" / "ball" - it's OK here - no problem.
I don't have Power Dock - so I'm speculating based on active-semi's ACT2801 data sheet and Onion's schematics only.
VIN Input Voltage nom. +5V (range +4.5 ... 5.5V), Absolute Max. +6.5V
VIN_OVP Over Voltage Protection typ. +6.0v (range +5.5 ... 6.5V)
So 5.4V was OK.
The IC has an Input Current limiter.
ILIM Input Current Limit - Omega's setting is R2=2.4kΩ about 1A - so the input current couldn't have been more than 1A. (It was 1.8A / 1.9A!)
Please try to recall. You might have done something else or something else might have happened.
Or simply this is one of those cases where Murphy's Law happened to be working.
I had a similar problem, the battery would not charge at all. It worked fine until I drained the battery completely, after that the power dock would no longer charge the battery. Just as a quick experiment I connected the battery to one of my adafruit feather boards and let it charge the battery for 15 minutes, after this it worked fine again and was charged by the power dock.
Omega is not really a solution if you plan using it with other power source than USB adapter.
I would recommend going for the AVRs and if you need for example Wi-Fi, you might consider connecting AVR to ESP8266 and so on.
Properly prepared AVR-ESP stack can be ran on standard batteries for many weeks, even months (of course it strictly depends on your project).
Is it possible to switch off wifi, and what current does it draw without wifi?
Yes definitely, you can easily switch off the wifi. On my bench an Omega2 draws 190mA with wifi on and 120mA with the wifi turned off.
Here are several ways to disable wifi -
During a session - in a terminal window the command "wifi down" turns off the wifi and "wifi" or "wifi up" turns it back on. Documented here near page bottom.
First I'll state the obvious... you will have a UART or appropriate dock for serial connection before testing this. By modifying the wireless config file, as mentioned here the Omega will turn off wifi while starting up.
You can toggle wifi off/on via a push button or a timer and the scripts, as detailed in those LEDE instructions. (edit - here the code tied to the "SES" button would be changed to work with input from a push-button on an Omega GPIO pin.)
That seems highly implausible, as the MT7688 isn't really designed for battery operated systems.
What you should probably do is use a microcontroller intended for ultra low power / sleep mode / wake on interrupt operation.
Have that occasionally power up the MT7688 (USB power switch, regulator with enable, etc) when it needs wifi. Make sure you either have no persistent file system state, or do an orderly shutdown each time.
Also consider if there may be another wifi solution that is a better fit for your application.
Info seems to be inconsistent and probably due to different designs from various manufacturers.
Also LiFePO4 is so new thus no long term stability report.
One thing that seems to be true is it does not have the same problem as Li-Ion/Li-Po (Li-Cobalt) as it has gas swelling problem -- and dead, when fully depleted.
I've seen one factory recommendation:
do not deplete below 2V and never go below 1.5v (as has potential to shorten the number of recharge cycles/usable life.)
@WereCatf so basically all of the 3.7V LiPo batteries found here can be used. Surely a low Ah model will last few but will charge faster than a bigger one. My concern is about the charging current available: if I use an high Ah model, my power dock will charge it without overheating?
It's not the capacity that determines the charging-speed, it's the charging-circuit that does. A 500mAh battery will charge at the same speed as a 2000mAh one, so it'll just simply take longer for the bigger battery to get charged full. That is to say, you could safely slap a 20,000mAh battery on it, if you wanted to :smirk:
Thank you! Now I guess for me, to have these work as household agents, I need to be either plug free or electrical system snap-ins. Otherwise, it's my parents' Christmas tree all over again. (You know the tree with 20 strands in an octopus tangle of plugs and extension cords.)
Maybe as a request to the Onion team or beg my EE friends to come up with a Onion dock or extension that puts the transformer there instead of at the end of the cord.The connectors would be splicing agents that would ride on the 120-volt wires.
Are you sure that your Omega GPIO pin is configured as an INPUT?
Additionally, the Application Schematic for the TPS61090 chip used in the PowerBoost indicates that a pull-up resistor should be used on the LBO line (see http://www.ti.com/lit/ds/symlink/tps61090.pdf). There is no such pull-up in the PowerBoost schematics
I would suggest a pull-up resistor on the GPIO pin used for the LBO - I guess around 10K Ohm should do.
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