Hi there,
This is my very first Post in this Forum and i hope that i will find some valueable advice here.
Iam from Germany so please ignore my language mistakes.
In the Picture above i have drawed the outline of a project that i would love to work on.
Its about Ships, Square Rigger Sailing Ships, 18th Century Period. Iam quite good at model building and planking ships and so on, so this is not the problem.
What iam looking for are ideas on how one could control the sails and some gimmics like cannons via ardunio and XBee (range is not nesscearry)
The Idea is to use a app or Pc programm to wirelessly control micro stepper motors (as Sail winches) like those:
(2Wire 2Phases 3-5 Volts)
and to heat up some Nichrome Wire to ignite some Model cannons onboard.
Problem so far is that i dont know about a stepper driver board that supports many of those mini steppers. Is there something like that? or are there other possebilities to control lets say 6+ of those mini steppers?
Everything should be as small as possible, to fit in relativly small 1:100 Scale Sail Ships.
In Summary:
A lot of small stepper motors should be operated but with very simple tasks like turn/step A specific amout forward or backward.
I could obtain one sure, but those are only examples, they can be bigger or different shaped - that does not matter for me.
Those small stepper motors are operated at 3 - 5 volts
Well a stepper motor driver is just that really...it does the job of firing the coils in the correct order. Maybe a MCU that simply fires the coils in the correct order when it receives a "step" and a "direction" signal may work?
The units are so small, the 20mA on each pin of the attiny85 may even be enough to power them directly with no need for transistors/darlingtons. Just get the coil max amperage, multiply it by 0.8 to be on the safe side.
If it is under 20mA...then if you run the Attiny on 5V, R=V/I = 5/I = the resistor value on the outputs you want.
So following from what you have written i should get one driver for each stepper? That is in fact what i wanted to prevent.
your other idea sounds promising still
Yeah, have you checked your calculations on the mechanics? These things are literally "the lightest touch". They are for pulling like laser diodes in DVD drives and such.
You can use a larger MCU like an Arduino Nano. Has 13 digital pins, giving you plenty of lines out. Each stepper there needs 2...so youd use 6 on the output. I do not know how your input works...but you have loads left over.
PS. Just looked up what 1:100 looks like...and are you 100% sure some slightly larger steppers are not an option?
They are the NEMA 8 stepper size. Uses a max 0.6A and is only 20x30mm in size!
The Pololu A4988 drivers are cheap on ebay (clones) and you need 3 of those for 3 motors.
That sounds great! Slightly bigger steppers arent a problem, so this looks like a good option, still is it possible to expand the available pins in future?
Btw you are right, these tiny steppers are not suitable forthe sails.
^ as Shpaget says, you can use shift registers (take a serial signal to give parallel outputs) meaning you could use just one pin + one as a clock to control 8 motors...but for the KISS method, you have plenty of pins on the arduino nano to play with for now.
Get a couple of shift registers and see what you think about them after playing a few tutorials (sparkfun etc.).
Johnny010:
The units are so small, the 20mA on each pin of the attiny85 may even be enough to power them directly with no need for transistors/darlingtons. Just get the coil max amperage, multiply it by 0.8 to be on the safe side.
The inductive spikes from the coils would kill the pins or reset your MCU. You need some kind of protection there.
Some corrections:
Nano has 20 IO - all can be used as digital pins, and not just D0 to D13.
No Arduino is going to be able to provide 0.6A, 600mA.
Shift register can be used to expand the outputs - but you need parts in the TPIC6x595 family. They work the same 74HC595, but only sink current, and with different pinouts.
TPIC6595:
Eight Power DMOS Transistor Outputs of 250-mA Continuous Current
1.5-A Pulsed Current Per Output
TPIC6A595:
Eight 350-mA DMOS Outputs
2-A Pulsed Current Per Output (Pulse duration ≤ 100 µs and duty cycle ≤ 2 %.)
TPIC6B595:
Eight Power DMOS Transistor Outputs of 150-mA Continuous Current
500mA Pulsed Current Per Output (Pulse duration ≤ 100 µs and duty cycle ≤ 2 %.)
TPIC6C595:
Eight Power DMOS Transistor Outputs of 100-mA Continuous Current
250mA Pulsed Current Per Output (Pulse duration ≤ 100 µs and duty cycle ≤ 2 %.)
They are nice and cheap but require 4 I/O pins each. Mind you, they come with a nice easy library and also you have 20 I/O pins to play with.
Goes with the keep it simple.
PS. this is like my idea with the attiny85...these are not real driver boards. The stepper coils are fired individually by the MCUs/Arduinos coding/software...not by a separate driver board.
