Ordered a DIYMall ESP32 DOIT Devkit board from Amazon and assumed that the data sheet would be readily available. Their website also appears to unavailable.
Is it safe to assume that the rated mA of a development board is the same as the ESP32 chip on the board?
Am a noob attempting my first project and just trying to collate the details of my intended circuit in an effort to try and learn how Ohms law dictates my design.
NO!
Also, 600mA is not the regularly rated current requirements of a ESP32's developer board.
250mA.
Thanks!
The 250mA is for if every pin was being used that's the current requirement.
So that's 250mA in total across every pin and back through the ground of the power supply powering the board?
I think I picked up somewhere that the GND pins on most controllers can act as connectors into your "ground out" wire. Is that correct?
I do not understand what you are asking.
What is a "ground out wire"?
I think this is where my rudimentary understanding of circuits and how they behave is holding me back. Here's my current understanding of it.
In this context, I am imagining a parallel circuit and the components sitting on branches of the overall circuit with the "ground out wire" being the section of the circuit which the current from an external power supply goes from the controller to the negative terminal/ground of the supply.
Current is not a constant. The ESP32 can draw up to 250mA.
Thanks mate.
Yeah just got back from catching up with a couple of mates who did electronics in the first year of their computer science degree and they, sheepishly, ( they weren't 100% certain from memory) suggested looking into what would happen if I added resistance to the circuit.
I've been approached solving/designing the circuit from the premise that I need to have current as the constant due to it being the limit of the components.
It seems that there is a way to adjust/manipulate the V = IR at any single point.
As far as i know, the 250mA is the total current for all pins combined, and there is a limit for every individual GPIO pin which is 40mA (wow same as an AVR) . Then there is the onboard 3.3v regulator and although the part has a max current of 600mA, this depends very much on the heatsink, for which in this case a part of the PCB is being used. Normally speaking the regulator does have an overheat-auto-shutdown feature, but still i recon it is better to check the datasheet. Realistically speaking that means that if you have external components and you are powering the whole thing with 5v, the regulator can supply the 3.3v to those components. The 250mA is for all current going through the ESP, in whichever direction.
For example : 8 pins Powering at 10mA = 80mA, 5 pins Sinking at 30mA = 150mA, total = 230mA.
what do you mean by that ?
Thanks @Deva_Rishi that's really useful context as I'm learning more about circuits.
Um, this is me positing something I need to explore and try and understand better.
For broader context, I've sought feedback in the project guidance topic where, in the interest self-driven learning/problem solving, I've asked that people's responses leant towards pointing me in the right direction as opposed to providing the solution if the person was comfortable doing so. @Idahowalker has been one of those people kind enough to spend a couple more brain cycles to provide guidance over answers.
I'm at a stage where I'm trying to understand the principles behind Ohms law in a practical application. So what I meant by the statement is that I must be able to manipulate any one of Voltage, Current and Resistance at any sole point in the circuit in order to work with the constraints of components. As opposed to Ohms Law only able to be applied to a circuit in it's entirety.
For example, if I have 5x 5V dc fans with a total current of 1000mA I must be able to either, change the current in series before it reaches the ESP or wire the circuit in a way (Series/Parallel) that means the current reaching the ESP is below it's rated limit.
It's an evolution of my thinking/understanding at this point in time when trying to learn electronics.
If you have 5v DC fans, you should use transistors or mosfets to power them and control those from the MCU, rather then seeking to power them straight from the MCU's GPIO's . (sorry for the abbreviations) and use an external PSU.
Thanks mate! Yeah that's where I've gotten to now and will be using an external PSU.
I think the step that I'm yet to fully unlock my understanding on is how the current will behave when the fans and the MCU are powered by the same PSU.
Similiar to the diagram in this person's answer on stackexchange.
Just trying to wrap my head around how to reconcile "a common ground" to be able to read from some sensors.
Edit:
Wait a second just looked through the diagram more deeply. This is the answer! Thanks @Deva_Rishi Legend!
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