This project implements the functions and methods needed to control the stepper motors of the SkyPointer project with an Arduino UNO and a CNC Shield.
The Arduino controls two 200 steps/revolution stepper motors (azimuth and altitude) running at 16 microsteps per step. The azimuth motor is connected to the X driver, and the altitude motor is connected to the Y driver.
The Z-axis driver in the CNC shield is substituded with a custom board that controls a green laser pointer and a photodiode. The photodiode is used in the homing process for locating a reference angle of the altitude axis.
The laser pointer can be enabled or disabled using the ZDIR pin of the CNC shield. The photodiode can be read through the ZSTEP pin.
The SkyPointer is controlled with a simple ASCII serial protocol.
All the serial commands start with an uppercase letter and end with a carriage
return \r. Some of them require one or two arguments, wich are separated by
spaces.
- Id:
I\r. Read the version string. - Goto:
G XXXX YYYY\r. Move both motors to an absolute position in microsteps. - Move:
M XXXX YYYY\r. Move both motors a relative number of microsteps. - GetPos:
P\r. Get the position of the motors. - Stop:
S\r. Stop both motors. - Home:
H\r. Move the altitude axis until the photodiode is triggered. - Quit:
Q\r. Release both motors and switch the laser off. - Laser:
L enable\r. Enable or disable the laser. - ReadCalib:
R N\r. Read the calibration value (32 bit hex integer) at position N (from 0 to 3). - WriteCalib:
W N XXXX\r. Write the calibration value at position N.
The code can be compiled and uploaded to the Arduino using make.
The provided Makefile requires Arduino-Makefile
to work. In Debian/Ubuntu/Mint, you can install it with
sudo apt-get install arduino-mk
You will need the following third-party Arduino libraries before compiling this project: