I am a complete novice in this, but I'm going to attempt to create a so-called star tracker. I have found many examples of such, but lacks a little more information about what else I need to be able to make it.
Here is an example of what I want to create.
I've ordered these parts:
Due R3 Board SAM3X8E 32-bit ARM Cortex-M Controller Compatible For Arduino
LCD Keypad Shield, 2x16, 1602, for Arduino UNO, Mega2560, R3
A4988 Stepper Motor Driver + Heatsink
NEMA 17 stepper 40mm length stepper motor
What more do I need to connect them together?
And how do I connect these together?
spycatcher2k:
3.3V main board with a 5V shield - No guarantees of compatibility - you would of been better getting a mega2560. This is only my opinion.
Auch, didn't notice that.. Oh well, I learned something new
As preparation before the parts arrive, I've tried to set up a sketch on how to connect everything together. This is as far as I've come. With my extremely limited knowledge of electronics, I've probably done something wrong or missing something wires or something.
Hi,
How do you plan to get the press buttons to work?
If you are trying to copy the analog method that is on the LCD/Pressbutton Shield then what you have will not work.
You have enough spare I/O to give each button its own digital input.
TomGeorge:
Hi,
How do you plan to get the press buttons to work?
If you are trying to copy the analog method that is on the LCD/Pressbutton Shield then what you have will not work.
You have enough spare I/O to give each button its own digital input.
Tom...
I just followed a schematic of how to connect buttons to the board. Have no idea if it will work
Here is a schematic view
And Parts list:
Arduino UNO R3
A4988 stepper motor drive
NEMA 17 bipolar motor
16 pin LCD screen
3 pushbutton (Start, reset and pause button)
3 resistors 2.2ohm (for the pushbuttons)
1 resistor 220ohm (for the screen)
1 potentiometer (for the screen)
1 Switch (on off power switch)
1 capacitor 47µF
1 battery (8x AA batteries)
if you have 5 volts, and all 10k resistors.
you have
5 volts at #1
3.33 volts at #2
1.66 volts at #3
voltage dividers all ways use power, so are not preferred when batteries are involved.
using 10 k resistors to limit the current used.
any 3 matching resistors will have outputs. higher values will use less power.
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need more power. I have a feeling you have not calculated how much power you will draw with a stepper.
think more like a car battery than AA cells.
this set-up will work, but is not efficient use of power on a few levels.
the Arduinos are not designed to be run on Batteries.
they can be made to run on batteries. but out of the box, they are designed for wall power.
you will need to power the LCD as well.
for a bench, it is not a lot of power
for batteries it is a hungry beast.
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you do not show the Arudino getting power.
need a separate power source for that.
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depending on your display board, you may or may not be able to pwm the lcd.
some were laid out wrong and the pwm could not work without modifying the board. cutting one trace and soldering in a resistor
As I mentioned in the first post, I have almost no idea what I'm doing. Everything I've done up to now is to see how others have done similar projects and tried to adapt it to my project.
I am trying my best
Is there a way to reduce power consumption?
I need this to be able to run on 8 AA batteries.
frabraha:
As I mentioned in the first post, I have almost no idea what I'm doing. Everything I've done up to now is to see how others have done similar projects and tried to adapt it to my project.
I am trying my best
Is there a way to reduce power consumption?
I need this to be able to run on 8 AA batteries.
the motor is the largest draw of power. you might be able to use a smaller gear motor and an encoder. steppers are power hungry.
loose the LCD or make it really dim. for night work you might be able to make it really dim.
as for the Arduino, you might considder getting a pro-mini.
need to loose the LED for power, loose the USB chip.
sleep mode is not too much of an option as you need to pulse the motor and driver the LCD
or sleep and pulse and sleep.
get a battery charger for the rechargable batteries. make sure they are of high capacity. cheap ones do not have the same rating as high output.
since you are only doing a few shots and each will be short, have a power kill switch and automatically kill the power after your use. press a button to start, let it time out and shut off. link the shutter to the on/off. allow the settling after start and shut it before you turn off the motor.
watch the scene from Jurassic park with the water showing the vibration. put a cup on your unit and see what effect the shutter does to vibrations. we used a black painted cardboard cover, held in place over the tele. opened the shutter, allowed the vibrations to subscide, removed the disk from in front of the lense, placed it back over the lens and then closed the shutter. the shutter movement on our SLR was horrendous !
All star tracker I've found have been made using the stepper motor, and is recommended for this use. I ordered a NEMA17 motor, and I'm getting a smaller version with a kit called 28BYJ-48.
I have also read that you shouldn't bring power directly into the UNO but through stepper motor drive. As I thought I had done.
I have a bunch of Eneloop AA batteries that have 2000 mAh capacity. Shouldn't that be enough?
The UNO draws just 50mAh from what I can figure out.
