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STEM KIT DEVELOPMENT

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(@denisalyanak)
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Joined: 1 year ago
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Hİ I'm Denis,

For my newly developed mechanical kit, I need to have remote Servo and dc motor control abilities. I started work on ESP32 development card. The youtube videos and lecture pages givesvery valuable informations about what i need.

I have some questions. I started with ESP32, but I need to know If this is the right choose for my needs(I wish it is).  With closely budget, do you suggest any other CPU or development card to drive, 4  or 5 Servo motors at the sime time or DC motor directly from the card(Without any additional interface card). My Second question is: If i can DC motor directly with without additional drive card, with ESP32 wroom 32U and drive 5 servo at the same time directly with ESP32 Wroom32U. 


   
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Will
 Will
(@will)
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@denisalyanak

I don't use ESP32s at all, but a quick Google leads me to believe that the maximum current draw on an ESP32 pin is 12 mA.

That won't allow you to drive even one servo directly from a pin and running a DC motor of any size directly from a pin is also extremely unlikely.

You'll need to search for motor drivers and also for servo modules. These will use the input from your ESP and an outside power source and provide the power you need to operate the motor and the servos.

I had a psychic girlfriend but she left me before we met.


   
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Ron
 Ron
(@zander)
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@denisalyanak Bill (dronebotworkshop) just produced a video on DC motors and several drivers. Any CPU or MPU can control the driver cards but the newer MOSFET based controllers are more efficient so have less heat created.

Here is video link

 

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PLI/1, Pascal, C plus numerous job control and scripting languages.
Sure you can learn to be a programmer, it will take the same amount of time for me to learn to be a Doctor.


   
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(@denisalyanak)
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@will 

Which CPU you prefere? Can you advise other CPU capable to the the things


   
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Will
 Will
(@will)
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@denisalyanak

I don't believe that any of the popular microControllers will be able to drive 5 servos and a DC motor directly. Everything will require an intermediate driver to provide power to the motor devices.

Ron has already pointed out an excellent source of information about DC motor drivers and Bill has also done several videos about servos.

You can also check Amazon, eBay and the other usual sources for servo controllers, many of which can operate several devices simultaneously.

I had a psychic girlfriend but she left me before we met.


   
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(@davee)
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Hi @denisalyanak,

  Before rushing into the finer accounting details of counting pins on microcontroller cards, to see if they can drive 5 motors at the same time, start by considering the requirements for just 1 motor.

  • A 'bare' motor, that is a motor without any electronic circuits hidden in the case or elsewhere, will typically require currents in the range of Amps to provide enough power to do something useful. Whilst some small motors run on voltages below 5V, a higher voltage is usually required, and more efficient, for a motor that must deliver a significant mechanical power.
    •  
  • Some "motors" are a 'package deal' of an electronic circuit plus the physical motor. The 'package deal' can take almost any form, including the possibility of two groups of connecting wires. 1 group providing a low power control interface, the other group being higher power to provide a supply of 'raw' power to the motor itself. The electronic circuit then forms an 'invisible' interface card between the physical motor, the control interface and the 'raw' power input.
    •  
  • Microcontrollers are (usually) optimised to provide efficient, low power computational capability. Consequently their output connections can only control small currents, rarely exceeding 10s of milliAmps, sometimes much less, and at voltages less than 5V. Only exceedingly small motors for something like a clock could directly run on these power levels.

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Thus, only certain motors which include an appropriate 'package deal' of power electronics can sensibly be connected to a microcontroller without the use of a 'separate' power control interface board.

Commercial products with high power motors, for example a washing machine, may have a single board of electronics incorporating both microcontrollers and power electronics, but this is only a convenient packaging exercise of combining the microcontroller and power electronic components onto a single customised card.

Readily available microcontroller cards, such as the Arduino range, typically avoid including high power interface components, because the design would only match a very small number of different users' requirements.

Similarly, most motors are supplied as 'bare' components, leaving the user to choose an appropriate power control interface.

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However, certain specialised markets, such as radio controlled models, have a large enough market to sell some motors with integral power control as a 'package' deal.

Many of the 'servos' supplied for this market are in this category ... the form of the electrical interface emerging from the servo device varies, but as an example, one type has three wires or pins:

  • Higher current, positive DC voltage supply input
  • Low current, logic. 3-5V maximum, control input
  • 0V 'ground' wire, common electrical return to both the power and logic circuits

It is possible to control one of this type of servo from a single microcontroller pin, provided the pin has the requisite capability, including compatible voltage level and often a PWM generation facility to produce the requisite waveform.

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Obviously, as a bare minimum to drive 5 such servos, the microcontroller would require 5 such pins. There would also be other be other requirements, including sufficient computational power to run the associated software at the required rate.

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From the above, I hope it is apparent that you need to start by choosing appropriate 'motors' for the task you envisage. In some cases, you may be able to find motors with built in electronics to meet your needs, whilst in other cases it will be necessary to provide separate interfacing electronics.

Having achieved that part of your design, you will be in a better position to consider your microcontroller requirements.

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I would add, that Bill ... @dronebot-workshop, and the host of this forum, has produced an amazing range of really clear videos and accompanying blogs to describe typical examples of these types of motors, servos and control intefaces ... I recommend you start your research by checking them out.

Best wishes with your project, Dave


   
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