Sleep mode

Are there any features that you would like to add to the VESC?
ViennaTom
Posts: 41
Joined: 21 Apr 2016, 13:06
Location: Austria/Vienna

Sleep mode

Postby ViennaTom » 29 May 2016, 11:21

Hi,
Maybe it would be nice to support some kind of sleep mode in which GATES and unused parts of the STM are powered down and the processor only polls for a wakeup event. I don't know how much power the buck converter uses by itself and maybe such mode would only make sense with battery supply (VBat) and the buck converter disabled. My VESC like unit takes 100mA when idle which i consider quite a lot, so maybe it is worth connecting the BUCK_EN pin to the STM and allow some hibernate or sleep mode ? I plan to use 8 VESCs on a bigger drone which will result in more than 0.8A consumption even when all motors are stopped - a short startup delay would not bother me too much on the other hand.
Greets, Tom
Last edited by ViennaTom on 29 May 2016, 12:25, edited 2 times in total.

scienceworks
Posts: 29
Joined: 27 Mar 2016, 16:27

Re: Sleep mode

Postby scienceworks » 29 May 2016, 12:06

i would be interested in such a feature too.

maybe a SSR (solid state relay) that cuts the battery connection? it looks like the vesc is able to bootstrap itself:

viewtopic.php?f=6&t=220

edit: the best thing would be to have the vesc charge the caps to the same voltage as the battery before switching the relay, that way the switching current would be very small. we could get away with using a small and cheap car relay, the only thing that matters is the ON resistance of the relay.

edit2: http://www.ebay.com/itm/DC-12V-30A-4-Pi ... SwubRXJExc
even such a small relay should be enough. (but the relay needs to be powered, a flip flop would be better)
Last edited by scienceworks on 29 May 2016, 16:15, edited 1 time in total.

scienceworks
Posts: 29
Joined: 27 Mar 2016, 16:27

Re: Sleep mode

Postby scienceworks » 29 May 2016, 12:37

ViennaTom wrote:so maybe it is worth connecting the BUCK_EN pin to the STM and allow some hibernate or sleep mode ? I plan to use 8 VESCs on a bigger drone which will result in more than 0.8A consumption even when all motors are stopped - a short startup delay would not bother me too much on the other hand.
Greets, Tom



ok for your use case the bootstraping approach wont work, and just switching off the buck converter in the DRV would be somewhat of a hard shutdown, you need some external supply voltage to keep the STM running.

hillso
Posts: 1
Joined: 25 Feb 2017, 12:08

Re: Sleep mode

Postby hillso » 25 Feb 2017, 12:54

do you think it will be possible to attach a switch (or a button, hardware or software debounced) to power on / off the VESC 4 (off = standby?)?

TC2117 regulator http://ww1.microchip.com/downloads/en/D ... 21665D.pdf
Image

stm32f4 http://www.st.com/content/ccc/resource/ ... 096220.pdf
Image

pf26
Posts: 278
Joined: 28 Mar 2016, 14:37
Location: FR Valence

Re: Sleep mode

Postby pf26 » 25 Feb 2017, 15:40

I think a switch between the bus high voltage and the V_supply connections to the DRV8302 should remove all current consumption (but leave the dc capacitors charged).
It is necessary to cut a pcb internal track, thus I proposed to remove vias instead (As I explained here : http://vedder.se/forums/viewtopic.php?f=7&t=363#p2214 - I never did it though.

benjamin
Site Admin
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Joined: 15 Dec 2015, 08:38
Location: Sweden
Contact:

Re: Sleep mode

Postby benjamin » 05 Apr 2017, 12:17

I have been thinking of implementing a sleep mode for a while, and it is possible to get the power consumption of the STM and buck converter down quite a lot. Putting the STM in sleep mode and disabling everything that can be disabled can probably bring the consumption down to below 200 µA for almost everything, the only problem is that the input voltage measurement divider will still draw a bit over 1 mA at 50V input (the blue LED will also consume a bit, but it is not needed). Shutting the buck converter down with the enable pin will turn the 200 µA to something like 2 µA, but the 1 mA still remains. To deal with that it would be necessary to switch off the voltage divider, which requires two small FETs and a few resistors (just using a FET on the low side does not help since the clamping doide in the stm will still sink the current). Adding the two FETs and an input for a power switch could be worth it though, if triggering the switch from software is possible. I have already killed a bunch of batteries by forgetting the power on.

On the other hand, when I'm finally done with the VESC6, the new software release and the homepage launch I want to design the ultimate BMS that handles functions such as this and also deals with charging and balancing the batteries from various inputs, but it feels like this is quite far in the future and possible even after a few VESC designs in different form factors since that has a bit higher priority for now.


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