@Jack, perhaps an injection of reality is required here. The Core, Photon and Electron are based on the STM32Fxxx series of processors. These have a VBAT pin with very clearly defined function that cannot be changed.
I think what you are proposing is a power management system which includes a rechargeable battery and which allows monitoring of voltage conditions on both the battery and the (USB) supply. The user code could then take action based on the power supply conditions. I believe this functionality will be available in the upcoming Particle power shield.
@peekay123, I may be asking for more than can be provided (I was asked how I wanted VBAT to work).
With the limitations of VBAT, It seems to be a useless pin (with all due respect).
It does not trickle charge the battery.
It does not allow the program to restart
As of this week, it does not even save variables.
I agree with you, putting a battery on the 5volt line would be the way to go if you want VBAT in theory.
So, do you agree or not that VBAT is useless? Else, how can it be useful.
@Jack, VBAT is a common function of most microprocessors, including some Atmel processors (think Arduino). None support the functionality you are looking for. The pin is design to assist in configurations where power may be turned off but program āstateā needs to be preserved without using eeprom for example. With careful design of supporting hardware, your desired configuration can be achieved, just not using VBAT. So in this respect, I respectfully completely disagree that VBAT is completely useless.
@peekay123, then on the Photon, how would the VBAT be useful?
If the system comes back from a power outage, and does a reset, whatās the use of VBAT?
thanks for helping me understand.
Thanks @peekay123 for your help. I donāt understand your request to stick to the topic. You and I have both discussed the VBAT under this thread. What do you mean? There is a new thread for VBAT I started. Should we migrate over there? Sounds good to me.
@Jack - Iām new here and still waiting for my Photon (itās coming tomorrow!), but I think I see the confusion here - perhaps I can help.
I think youāre thinking about VBAT as managing a battery like a UPS - probably a LiPo or supercap that would keep the processor (and WiFi etc.) running when power was lost.
A better analogy would be that of the āBIOS Batteryā from PC Motherboards. They donāt keep the machine running, they just keep the clock running and store configuration data (what drives you have, how youāve configured the peripherals etc.
The Photon has the ability to attach a battery (likely a coin-cell) for this purpose: however the current firmware doesnāt expose the ability to store user data in that configuration area (yet).
If youāre looking for UPS-style battery management, the upcoming Power Shield is going to provide that. Or you could use something like the PowerBoost 1000C from Adafruit which provides exactly what youāre looking for: https://www.adafruit.com/products/2465
@peekay123, @Jack, I didnāt see any actual measured current values in this thread. Here are some measured values I came up with when supplying 5V to the Vin pin (Note this is after the 0.4.4 update on the Photon).
To me it seems a little odd that the current draw is so much greater in STOP MODE. Our application requires the retention of variable values and processing location which is provided in STOP MODE. Any ideas on how we can lower the power consumption in STOP MODE further? I assume the wifi chip is turned off during STOP MODE?
Stop mode requires a pin interrupt to wakeup, correct ?
System.sleep(seconds) alone only disables WiFi, and still draws significant current.
I measured deep sleep to 90ua, but that was a few firmwares back, havent used it for a while since I ran into a bug where the device would sometimes not wakeup, and the issues with OTA updates and deep sleep.
@MORA, Thats absolutely right! I assumed that these two calls were equivalent in powering things down.
System.sleep(60);
āUser code will continue running while the Wi-Fi module is in standby mode.ā
System.sleep(D0,RISING,60);
āIn this particular mode, the device shuts down the Wi-Fi chipset and puts the microcontroller in a stop mode with configurable wakeup pin and edge triggered interrupt.ā
I will measure the current in STOP MODE and post what I find. Thanks for pointing that out!
@peekay123
Hello. I plan to use my photon as a portable weather monitoring system which will involve the photon being connected to wifi/cloud continuously taking measurements from a a few sensors and communicating that information via bluetooth to mobile application. I need to determine what battery capacity will best fit this application. i read through the particle doc on the power requirement but it does not provide much information on the matter except to say that the photon will consume 80mA with wifi on.
I would like to know how much power the photon itself would consume/require if it was there was a constant wifi connection and transmission of data (through bluetooth). I will add this power consumption to the power consumption of my sensors to determine the total power requirements of the design.
Is there an official document i can make reference to or a reliable website where this information is published?
The docs say 80mA. Beyond that, you should hook up a current meter and test in your own environment. There is no Bluetooth built into the Photon so you will have to look into Bluetooth power consumption separately. Also, you havenāt stated any requirements for desired run time between charging, without which no one can guess at the correct battery capacity for your application.
Yes i know the doc mentions 80mA and short of a meter i wanted to know what the power consumption of the photon itself is (which I did mention in my post). I am aware that the photon does not have built In Bluetooth and I intentionally didnāt mention the other devices I will be connecting to the photon becuase I will calculate their power consumption separately.
@Alli, I sense a certain edge on your response to @ninjatill. He is trying to help. The specs are quite clear. You will need to consider an operating current of 80-100ma for the Photon running with WiFi ON and a peak WiFi connection current of 235-430ma when establishing a WiFi connection (and transmitting data). The latter specification is to ensure that your battery can handle such short burst peak demands. Hence, average Photon consumption = 80ma with average peak of 350ma.
One thing you did not specify is whether you expect to power the Photon via USB or Vin (5v) or with 3.3v directly to the 3V3 pin.
@ninjatill@Rftop@peekay123
Good day all. Thank you for your replies and advice.
No edge was intended in the reply. I apologise if it came across that way since I was rushing to respond. I hope you didnāt take offense ninjatill.
The device will be constantly communicating data via Bluetooth to a mobile application so will it be consuming 235-430mA?
I intend to power the photon via Vin.
I think a reasonable amount of time for the device to last on battery would 4-5 hours.
You also say the Photon will be continuously connected to WiFi and the Particle Cloud. So, do you really need a separate bluetooth feed from the Photon to a mobile app? Why not have the app pull data from the device via the Particle Cloud?
Regardless, the "continuously communicating" part is not clear. Will you be publishing to the Cloud or using direct TCP to your own server? The reason I ask is that Publishes are rate limited so this will reduce the average current consumption. Generally, I have seen nearer to the 80ma consumption in these circumstance. If the Photon is working hard at interfacing with other sensors you may get up to 150ma. The 250-430ma rating is a short peak, non-continuous value and you need to make sure your battery can supply that.
I agree with @peekay123. Iāll also add, if you want a crude calculation with the limited details we have, you would typically multiply the average, continuous current (in mA) by the desired run time. So for what you provided 500mA (rounded up from 430ma) * 5 hours (longest desired run time) = 2500 milliAmpHours (or mAh). Luckily most batteries are rated in mAh so itās easy to choose. If you have a mix of 3.3v and 5v sensors, you have to account for losses in whatever voltage regulators you use. You may also want to estimate 20% higher to give yourself a cushion and account for the practice of putting the device into deep_sleep mode when the SoC drops below 20% (to prevent firmware corruptionā¦ mainly on the Electron but I donāt think the Photon is immune). I have a larger batter pack for my cell phone that is rated at 11,000mAh which is way more than your askingā¦ just be aware, with the typical phone power packs, they shut themselves off in periods of low current draw. There are other discussions on this forum about that if you go that route. @peekay123, @Rftop and @RWB may have better battery recommendations if you state your desired setup in terms of physical design and desired charging methods. Good Luck!
@peekay
I am my primary choice is bluetooth becuase this was the requirement of this project. I am considering incorporation of communication via the internet using the photons built in wifi capability but only if time permits. So I would like to allow myself the ability to do so, in terms of power requirement, should the opportunity present it self. I am still at the onset of the project and after the advice shared from this thread I think I should design the battery/psu system further on in the project when I have a more definite design. Thank you your advice.
@Ninjatill
Thank I will remember this when completing the design of the PSU. Thank you for the luck and advice.
