Electron schematic help

Try going straight to Vin and Ground..... not using the Screw Terminals.

Can you explain the issues with the screw terminals and USB concept? (schematic below)

See Below:

Try Just the "Yellow" Connections below for Vin and Ground:
image

I'm only asking because I think this is how I fried my first electron...

Is this what you are suggesting?

  • Allows full functionality without the Electron's LiPo?
  • Won't damage the electron board?

Yes, Vin is rated for 12V. But if you’ve already done this and had problems…then No.
You may have transient voltage swings during the startup with all your peripherals?

It looks like CAPS are your best bet.
Hopefully others will chime in again. We’re past my limited knowledge.

Here is an old post from when I fried my first electron.
I had tried VIN/GND then stupidly tried VBAT/GND

That says you Smoked it with VBAT, which is understandable.

Another thought, You may damaged the Asset Tracker in previous testing up to this point.
With Nothing else connected, will your Electron work properly in the Asset Tracker right now with the typical 12V on the Screw Terminals ?

This is my 3rd Electron (and last), so I’ve been very careful to not damage it. (that’s why all the questions)

It works just fine with the electron’s LiPo and an auxiliary battery connected to the screw terminals to support the servo and LED strip.

The problem is when the device is put into service it may sit idle for a year of more. The auxiliary battery has an in-line switch completely disconnected it until it’s needed. I need it to power everything when the switch is made.

The electron’s Lipo it will drain completely before it’s needed, so I need to eliminate it. I don’t want to add a second switch.

Some background… This is a public safety warning device that will save lives, so it needs to be as robust as it can possibly be.

Ok… I tried VIN / GND with no lipo.
The device started up and ran properly until I increased the LED brightness to maximum, then it froze with the LEDs on red

They flash the following sequence

  • red 20ms
  • black 20ms
  • yellow 20ms
  • black for 8000ms

I disconnected power, then hooked up just the LiPo, and got a dark blue breathing pattern from the electron, I thought for sure I ruined another board

I powered it back down, put the wiring back the way I had it, and it’s now running normally with both the main batteries and the electron LiPo

Sounds like you are having problems with Voltage drop.
It could be that the Battery pack or wiring can not handle the Amps from the neopixels.
Or the high current required by the neopixels is causing problems for the Electron (not a stable Supply Voltage, dirty power with the spikes, etc).

This could only get worse as the battery pack's capacity is consumed over time. As battery Voltage Decreases over time, the amp load increases.

If you go the route @peekay123 mentions, you can use whatever Battery Voltage (up to 12V) that you want for the system.

Is the Primary function to have the Electron publish the Alarm to the Cloud, or the local Alarm/lights ?

Both, the lights and beeper alert anyone near the hazard of danger. Cellular messages are sent to the municipal dispatch center to dispatch an appropriate emergency response.

The lights, servo, beeper, cellular and GPS all work properly with these two configurations:

  • Main batteries and LiPo
  • Main batteries and USB cable

Which is why I’m asking if I can route the main battery to both the shield and the usb connector?

Going back to using a micro USB cable to send power from the shield’s screw terminals (auxiliary batteries) to the Electron (see the schematic below)

Above in this thread there have been a lot of great alternative suggestions offered, but many are not applicable for this device’s specific requirements, and some seem over complicated since the Asset Tracker’s documentation clearly states it should operate on auxiliary power alone. (unfortunately a car/motorcycle battery is not an option due to size and weight)

No one has answered if this usb jumper approach will or will not work, and if not why?

In my mind this is the simplest solution based on the fact that everything works correctly with the external batteries to support the LED & Servo power requirements, and the USB cable to support the electron (without the need for the small LiPo included with the asset tracker kit).

Again, the device must be self contained and will be remotely deployed, and could sit idle for a year or more before powering up. So the electron’s LiPo if used would be long dead when the device detects a hazardous condition.

It is a small compact public hazard warning device which flashes the warning lights and sounds the beeper local to the hazard, while also sending a cellular message with the GPS coordinates to the city’s emergency dispatch center.

The fact that the Electron operates when 2 Power Sources are used does reinforce the idea that you are overloading the hardware with peak demands from the neopixels (but that’s still just a guess).

I know you mentioned that you didn’t want to add a 2’nd door switch, but that would allow you to have (2) battery packs and completely isolate the Local Alarm from the Cloud Alarm/Electron.
Redundancy is a benefit, especially since this is a Public Safety Device.

Point taken, I’ll try to find a DPST micro switch that will fit

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A couple of comments -

  1. Someone mentioned that the usb cable will block the GPS antenna. My understanding is that that was a real issue with the V1 AT, but not the V2 one. I have a V2 and it connects fine with a straight-in USB cable connected, even while indoors (but next to an exterior window).

  2. Have you considered reducing the number of NeoPixels that you’re using? They’re so incredibly bright, I wonder if you need that many. E.g. get a strip with wider-spaced NPs.

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  1. With the AssetTrackerRK library I have had no trouble getting a GPS fix with the USB connected. (The old library had trouble either way).

  2. The leds need to be as bright as possible so they can be seen day or night from a distance. I’m only turning on the leds after a two minute timeout period… then only for two 20 millisecond flashes (one red, one yellow) every 8 seconds thereafter. The device is permanently mounted, so I only need to get a fix when the device first powers up. (holding the location data as a string) after getting a fix I’m turning the GPS off before the initial timeout ends and the leds start flashing. The servo actuates only once when the device first goes into hazard mode. As for the cellular, it’s send-only, one short data message every hour, the webhooks handle the email functionality.

Success!
(well sort of?)

I just tried what’s shown in the schematic below and it’s working with just the LiOn 3 cell batteries for power.
Previously I don’t think all of the grounds were correct.

  • With the LED brightness set on 50 everything works normally.
  • If I set them to 100 the whole system reboots when the LEDs flash, I assume I have a power loss to the electron
  • If I set them at 255 it freezes up on the first flash with the lights stuck on, I have to power-cycle the system for reboot.

I’m going to have a look at the code to see if I can make sure no other functions get executed while the leds are “ON”

(Please see the above post)

Going back to previous suggestions… If I were to add a capacitor between VIN and GND how do I figure out the right size to keep the electron powered up for 60-80 milliseconds?

This is the total time I’m dealing with the leds (one cycle every 8 seconds)

  • On RED 20ms
  • Off [BLACK] 20ms
  • On [YELLOW] 20ms
  • Off [BLACK]

I am planning on modifying the code to assure no other functions are called for the duration of the flashing sequence.

Researching capacitors and boost converters I found these: https://www.amazon.com/dp/B07CNQPN94/ref=sspa_dk_hqp_detail_aax_0?psc=1

What’s not clear to me is do I still need a 1-2f supercap on the output to keep the electron from fading out when the LEDs are on?