Power for the Raspberry Pi Pico - Guide to using VBUS, VSYS and 3V3 for external power circuits
ฝัง
- เผยแพร่เมื่อ 21 พ.ค. 2024
- This video covers all you need to know about powering the Raspberry Pi Pico, or using the Raspberry Pi Pico to power external circuits. It will help you to understand VBUS vs VSYS and how to safely connect to external power and USB power at the same time. It also includes circuits for powering the Pico or using the Pico to power other circuits using the 3V3 pin.
The following circuits are included in the video:
* Raspberry Pi Pico Schematic (power section)
* Powering the Raspberry Pi Pico through VBUS
* Powering the Raspberry Pi Pico through VSYS
This mostly apply the same for the Raspberry Pi PicoW except that there is a different model of buck-boost convertor used in the Pico W.
For more details, including the circuit diagrams and a schematic of the Raspberry Pi Pico power section see my guide to powering the Raspberry Pi Pico at: www.penguintutor.com/electroni...
Understanding AC to DC power conversion (video):
• Model Train Automation...
Controlling NeoPixels on a Raspberry Pi Pico using CircuitPython:
www.penguintutor.com/programmi...
Guide to MOSFET level-shifters for controlling RGB LED NeoPixels: www.penguintutor.com/electroni...
Chapters:
00:00 Power to the Pico
00:35 Powering a Pico
01:18 Pico power specifications
05:36 Pico Power Pins
12:42 Power circuit diagrams
18:32 Special Situations - วิทยาศาสตร์และเทคโนโลยี
Detailed examination of the voltage requirements and more. Very clear and just what the doctor ordered!
This was a surprising useful video with no distracting music or suscribe bells. I had no idea that the pico provided a buck and boost convertor from VSYS power. Thanks for the video!
As written on the tin and no fluff!
Precisely what I was looking for! Thank you!
I don't think I've subscribed to a youtube channel in several years until today
Very good explanation of powering your pico 👍
Fantastic - so comprehensive! I'm going to be coming back and referring to this many times.
Thank you for that wonderfull lesson about powering the Pico.
This wonderful YT channel made me want to tinker with RPI pico. Super content, very clearly shown, without disturbing music, very competent help in the comments section.
An attempt to donate the money via PayPal was not possible and on YT without a credit card it doesn't work at all. A PayPal friends link would be helpful.
Thanks for your kind comments.
I may look into other options in the future. For the moment I'm happy with subscribes and likes as they help me to grow the channel.
Great video - very well explained - exactly what I was looking for. One minor gripe is that the audio is not very clear. but regardless - thanks for making the video.
I came across this most excellent video by happen chance and I'm sure it will come in very useful, thank you. I've subscribed!!
That's just what I've been looking for!
Thank you! Super helpful information.
Really fantastic post, thanks very much!
Very helpful thank you
very helpful video, thank you
very useful, thank you
just what I wanted
Well done
Awesome
Thanks
Nice Video. I'm currently investigating using a Pico from the 'bias voltage' from a camera audio input - this is use to power mics at 1.5-5v (but normally 3.3v)... Looks like it might work :-)
Thanks
Thanks for the very useful video. One question, though: You casually mention to use a Schottky diode. This is for the power supply, so a DC voltage. Then neither the higher switching speed nor the lower forward voltage drop of a Schottky diode seems to be important when using a 5V or even 3.3V external power supply. Wouldn't a regular 1N4148 or 1N4001 also be usable in such a situation?
I normally use a Schottky rectifier diode because of the low voltage drop. This means less power loss. Particularly when using a battery.
It's not going to be much in the grand scheme of things, but even a little can help.
Another potential benefit could be that if the voltage from the power source is greater than USB then that will be dominant, although if that is important a MOSFET would be a better option.
A regular rectifier diode would work fine instead.
I wounder if it would be possible to power the pico directly of the 3.3v pin assuming the onboard solution is turn off and the power source is a known good supply?
I can't see any reason why it wouldn't work, but considering you can just connect 3.3V to VSYS I don't see much benefit to doing so.
There doesn't appear to be anything that uses the VSYS supply, except as an output on the connector and as a voltage reference for ADC3 (so you can read the input voltage). I don't know how the RT6150B-33GQW will respond to having power at the output, but not at the input, but it would probably be okay especially as the enable pin won't be pulled-up.
The only advantage I see to bypassing the onboard buck-boost convertor is a slight improvement in efficiency due to the loses there, but those will be fairly small.
21:27 - irrespective of the voltage on the gate, internal diode of the mosfet is in wrong direction so mosfet will always allow voltage to pass ;-)
I think the mosfet should be opposite direction here
The diode of the MOSFET is the internal body diode, which is a characteristic of the MOSFET.
It could allow current to flow if the voltage of VSYS is lower than the alternative supply voltage minus the required voltage for the body diode to conduct.
If the MOSFET was connected in the opposite direction then it could allow backfeeding from USB (via VSYS) to the secondary power supply which is was the circuit is designed to prevent.
@@PenguinTutor that is correct of course, but to stop the backfeeding one more diode would help as well ;)
Do I need a Schottky diode if voltage supplied to VSYS is below 5V (such as LiPo battery)? Will the 5V from USB be supplied to the battery then?
Yes I do still recommend that you use a Schottky diode.
If a voltage source is higher then the battery then it will try and charge the battery. This can be detrimental to the battery and in some circumstances dangerous.
For a LiPo battery then you should be using a dedicated charging circuit. These are typically restricted current chargers designed to prevent the battery from overheating.
I'm using a Pico W in a project where I want it to be able to work (communicate) wirelessly or wired, is it safe to have some batteries (3 AAs) connected to VSYS and then also plug in to the USB port? Or in other words if I want to go from wireless to wired, do I need to take out the batteries or switch them off somehow before I plug in to USB?
Yes, just use a diode to prevent the USB power trying to charge the batteries. This is the circuit at 15.53 replacing the external power supply with your batteries.
@@PenguinTutor Thank you!
First thing: Which MOSFET should I use? Can you name one you would recommend the most?
Second thing: I often see the diode in the opposite direction on the internet. Can you explain the thing with the diode a little bit more?
In general: which components do I need to buy to best power my Pico (with and without W) with either 3.3 V or 5.0 V?
Do you mean the MOSFET used at 14:21 - used for switching a high power LED? If so then it depends upon the current requirement, a 2N7000 is good for up to 200mA, but for more than that you may need to look at one in a TO-220 package such as an IRLB8721.
What do you mean by a diode in the opposite direction? Do you mean across the MOSFET (that may be showing the internal parasitic diode), or across the load which could be a flyback diode to protect against back EMF from inductive loads.
To power a Pico I normally use a 1N5817 from a 5V supply to VSYS (pin 39) as shown in the VSYS diagram here: www.penguintutor.com/electronics/pico-power
Thanks for your fast reply!
All my questions refer to the improved powering of the Pico itself you are showing in the picture in 21:20.
I want to use a power supply made for breadboards, which can output either 3.3 V or 5.0 V. And I want to be able to connect the Pico to the PC at the time. From your video I understood, that I need to put a MOSFET and and diode infront of the pins of the Pico. But I don't know which ones exactly.
You can use the simpler diode based version which just takes whichever is the highest voltage. The diode projects against back feeding to either power supply.
The MOSFET version has a lower voltage drop and disconnects the external supply when connected to USB if that is what you want.
The datasheet suggests a MOSFET but I expect that is SMD. The main characteristic to look for is the maximum current, any P-channel MOSFET that can handle the required current should work.
Hi I did the same setup at 18:19 timeline in video. except the IN5817 i have used IN5819.. BUT the magic smoke appears when i plug the battery and usb both ...I fried my pico...a buck boost converter was attached with the lipo pack 5v. what is wrong here?
i checked with the microscope and found the onboard battery management chip got burned
Was your buck boost providing the correct voltage? The absolute maximum Vin for the Pico's buck-boost is 6V. I have tried some buck-boost regulators in the past and they have provided a much higher voltage especially with a low load. It's best to test with a meter before connecting it to the supply.
Other than that I can't see a reason for why it would do that. That is essentially the same circuit as provided in the Pico datasheet (page 19).
@@PenguinTutor Yes, XL6009 buck boost converter that I used in my setup. The output voltage set was 5.3V (tested via a multimeter yellow color model number DT830D). Another thing that I used IN5819 diode as a substitute on IN5817.
A question. Can I simply remove the buck converter from my circuit and use LiPo battery (with TP4056 1A charging module), keeping diode as in your circuit?
@@abhinavgolwalkar IN5819 should work fine as a substitute for IN5817 (higher voltage tolerance and slightly higher voltage drop).
Generally the boards with a TP4056 are designed so that you use that to charge your battery, then physically disconnect it from the charger and connect the battery to your circuit.
If you are looking to use as a UPS then you probably need a dedicated chip, perhaps the LTC4040 (I'm not familiar with that particular chip, just found on a quick Google, so you will need to check suitability).
If you are just powering the Pico then you should be able to connect LiPo through a diode to the VSYS pin, as you can run from as low as 1.8V. Note that this will mean that you don't have any additional protection from your LiPo (some LiPo batteries have built in short circuit protection which I would recommend). Again page 19 of the datasheet covers this: datasheets.raspberrypi.com/pico/pico-datasheet.pdf
" For example a single Lithium-Ion cell* (cell voltage ~3.0V to 4.2V) will work well"
I need an interruption to save some data if the power drops.
What if i want to use both the usb cable for data transfer and an external power source ?
If you want to use the USB power supply to power your own circuits then you can use the output from pin 40, the VBUS pin. This is shown at 6:11 in the video.
@@PenguinTutor I want to power the pico through an external source. I want to use the usb cable to transfer data from and to the pico and my lap top. How do i make sure that the pico draws power only from the external source and not from the usb ?
@@santosalex213To guarantee that you'd need to create a custom USB cable without a +5v connection.
If you use a Schottky diode to VSYS then as long as the external power supply is a higher voltage then that would be used in preference to USB.
Curent 1 to 150-160mA (lowest to max peak)
I want to power up a 5V logic sensor which pin should I use if I power up the pico using VSYS?
What power supply are you using to VSYS?
If it's 5V then you can use that. If not then you will need to use a separate 5V supply as the Pico does not provide any step-up voltage outputs.
If using a 5V sensor then make sure the data signal is compatible with 3.3V on the GPIO pins.
@@PenguinTutor want to use a battery. Let me ask in this way, with the diode in between VSYS and VBUS will it be possible to power up the pico using a battery through pin VSYS but powering up external circuitry using VBUS, as in the case when using a USB power supply?
@@happymatekenya394 No. It's one way. You can power through USB / VBUS and then use VSYS to power other components, but if you can't use VBUS as an output unless you provide power through the USB port.
Do you have a 5V battery? In which case you could use that for VBUS or VSYS and also use that to power your 5V logic.
If not then you will need external circuitry to increase the voltage to 5V - perhaps a buck-boost converter.
@@PenguinTutor I have a 9V battery
Thx for making that Video!
FULL BRIDGE RECTIFIER!!!
8:35
Your voice is not clear. Can't understand.
Do you have any specific questions that we can help with?