About interface projects...
https://coolcomponents.co.uk/products/grovepi-starter-kit-for-the-raspberry-pi
is a Pi sized board which fits on the GPIO pins.
It has a family of neat input and output devices both analogue and digital...
with a universal plug and socket arrangement enabling connection to the
board`s multiple sockets. A processor deals with the matching to the Pi
which is by I2C.
A low risk alternative to breadboarding for simple devices.
It provides a degree of voltage protection to the Pi , should anyone wish to
make a specialized peripheral .
Sent from Mail<https://go.microsoft.com/fwlink/?LinkIdU0986> for Windows 10
________________________________
From: raspberry-vi-bounce@xxxxxxxxxxxxx <raspberry-vi-bounce@xxxxxxxxxxxxx> on
behalf of Chris Norman <dmarc-noreply@xxxxxxxxxxxxx>
Sent: Friday, August 17, 2018 4:26:01 PM
To: raspberry-vi@xxxxxxxxxxxxx
Subject: [raspberry-vi] Re: Project Help
Hey Mike,
Thanks so much for all this wonderful info. I'll keep it here to read at
my leisure.
So from what you're saying: I need this L9110S jobby thing, 2 DC motors
(not stepper motors?), and 4 female to female jumper cables. Is that right?
I guess I also need cables to hook up power? More jumper wires?
Thanks so much,
Chris
On 16/08/2018 15:54, Michael A Ray (Redacted sender mike.ray for DMARC)
wrote:
Hello Chris
Each L9110S can drive two motors.
The way you change the direction of a DC motor is to reverse the
polarity of the power connected to it. This is what an H bridge
facilitates.
Connecting to an L9110S is done with female to female jumpers from the GPIO.
Connection to the motor is with screw terminals on the L9110S.
You can also drive the L9110S with PWM.
Reducing the speed of a DC motor can be done in two different ways.
One, which things like the model trains in a traditional train set did
it, is to turn down the voltage from the max. Problem with this is when
you drive a DC motor at under it's usual voltage, you also lose torque.
The other way is to use PWM, pulse width modulation. In this the power
is chopped into off and on pulses, like the teeth of a comb. By varying
the mark to space ratio, the percentage of time for which the power is
on is changed. The advantage of this is the motor can be made to run
more slowly but with the same amount of torque.
Also less risk of stalling. When a DC motor stalls it starts to draw
excessive current and gets hot.
With a single L9110S it would be possible to drive two wheels of a three
wheeled robot, the third wheel being a castor type. Then, if both
motors are driven in the same direction, the robot moves forward or
back, run each motor in opposite directions, the robot can be made to
spin. Run one slower than the other and the robot turns gently like a car.
Mike
On 16/08/2018 09:55, Chris Norman (Redacted sender chris.norman2 for
DMARC) wrote:
Hi Mike,
That's brilliant, thank you.
So I've looked into it, and I think I get how it works from bridge to
motor, but I have a couple of questions:
Firstly, how does it connect to the Pi? Does it sit directly on top of
the GPIO pins? Or do I need some kind of breadboard setup?
Secondly, how do I connect motors to it? Can this be done without
soldering?
Finally (I think), will this work with any kind of motor? Reading more
about motors et al, I want a motor that can spin in either direction. I
believe these are called bipolar motors? From what I've read it seems
that stepper motors are the only motors which can be bipolar, but I
could be talking rubbish, so please feel free to correct me.
Cheers,
Chris
On 16/08/2018 04:20, Michael A Ray (Redacted sender mike.ray for DMARC)
wrote:
Chris,===========================================================
Look on Ebay for an L9110S. This will be billed as a stepper motor
driver, but it also drives regular motors.
Basically it is an 'H' bridge. On a PCB about an inch square. Provides
a means of driving the motor in either direction.
Very cheap.
Don't try to drive a motor directly from GPIO pins. That will end in tears.
Mike
On 15/08/2018 14:16, Chris Norman (Redacted sender chris.norman2 for
DMARC) wrote:
Hi all,
I have a wee project in mind, and as usual have no clue where to start
with parts.
The project requires a single motor to be used for feedback (I want a
motor not a buzzer), and ideally I'd like the whole thing to be small
(although that's a bonus at this point.
Does anyone have any good docs on where to start? I know nothing about
resistors or any of that jazz, so any articles or books on the subject
would be golden.
What do you all like interms of breadboards and such? Do I even need one?
I've found the ModMyPi T-Cobbler Pro
<https://www.modmypi.com/raspberry-pi/prototyping-and-breakout-boards/gpio-breakout-boards-1026/modmypi-raspberry-pi-t-cobbler-pro-breakout>
and breadboard case
<https://www.modmypi.com/raspberry-pi/cases-183/raspberry-pi-b-plus2-and-3-cases-1122/raspberry-pi-b-plus23-breadboard-case>.
Am I looking in the right place?
I'll be working completely without sight, not sure if that changes the
answers or not.
Thanks so much in advance,
Chris
===========================================================
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The raspberry-vi mailing list
Archives: //www.freelists.org/archives/raspberry-vi
Administrative contact: <mike.ray@xxxxxxxxxxxxxx>
-----------------------------------------------------------
Raspberry Pi and the Raspberry Pi logo are trademarks of the Raspberry Pi
Foundation.
This list is not affiliated to the Raspberry Pi Foundation and the views and
attitudes expressed by the subscribers to this list do not reflect those of
the Foundation.
Mike Ray, list creator, January 2013
