HELP .. What board is the best for my telescope project?


I'm very new at this and need some guidance. I want to purchase an Arduino board that can do the following. I need a constant out put of 218hz ..when I push a momentary button it changes to 430hz when I release the button it reverts back to 218hz .. ect ..I have 6 buttons and when each button is pushed the hz changes . I'm trying to change a broken telescope timer board that controls the stepper drive..

The original board was a home made board from about 15 years ago using a 555 chip and a bunch of diodes and resisters and caps .. I want to upgrade to something more stable and off the shelf..

Like I said I'm new at this .. but I've done some programing for relay control software in VB6.. I don't want to purchase something that wont work.. any help would be most appreciated.

Thank you in advance.


Uno will do that just fine. Use it for development, than program a Promini with the coded for installation into your project.
Look at my post "piano tones micros" for generating the frequencies using "blink without delay" style code and reading pushbuttons to output frequencies whose periods (half-period actually if I recall) are stored in an array.
It's for 13 buttons, just trim it down to 6 buttons for your needs.

Thank you so much for the info.. I really appreciate it..

Is there any reason not to use the Arduino to control the stepper motors directly rather than just mimicing a 555 timer ?

Stepper motor basics


I'm not sure how using an Arduino is going to be any more "off the shelf" than your old 555 timer circuit. But in terms of being "stable", do you mean that the output frequency is more accurate compared to the desired frequency and less affected by temperate, presence of nearby objects etc?

I was going to suggest an attiny85. Its the same size as a 555 timer but can do all that stuff with buttons and frequencies. However, although it will be more stable and accurate than your 555 timer, an Uno or Pro Mini would be better still because they are equipped with a crystal, usually 16MHz. That will provide a much more stable accurate output.

So is the 218Hz signal to drive the stepper so as to track the movement of the stars as the Earth turns? And the other frequencies to move the scope around in that plane? Do you need to control the stepper in reverse also?


Crossroads has the best answer.

assuming your 555 creates a pulse that runs your star drive and the buttons are to re-locate to a new point of interest, the arduino is a great way to do that.

what Robin2 mentions is that if your interest is to replace a board and part of that board has all the transistors to control the stepper motor, you could buy a stepper driver. not sure how much that would help if your current driver circuit has been working for 15 years.

the beauty of the Arduino and putting much of the logic into software, and once you do that, there may be other benefits.
you can program one point and reference other points and have a pre-set 'go-to'
and example is if you site in on Pleiades, and then hit your 'home' button. everyting would be in reference to that point.

Then if you have Mintaka on Orion's belt as a pre-set point, you can hit one button and go to that set of coordinates.
Like a set of 'car radio buttons' that will move from your 'home' location to some pre-set coordinates.

similarly, you could add a button that just adds 10 degrees per press.