Linistepper Equatorial Stepper Drive

Roman has written an alternative firmware package for the Linistepper V1 or V2 to drive an equatorial mount at a precise and accurate rate. (Please note, this is NOT compatible with the 16F1826 used in the V3 kit. You can use the 16F628A as supplied here in the V3 PCB, with the external resonator we supply here) ceefna's excellent home built star mount for astro photography is the first using this new code. The code not only drives the motor but also generates a very accurate stream of step pulses which turns the motor (and so the camera) at just the right speed to cancel out the motion of the earth, allowing very long exposures which increase the sensitivity of the film and the brightness of the stars. Check out his excellent video:

ceefna has written a spread sheet that will help in calculating the correct values to enter into the program to adjust it for your mount gear ratio, which has been adapted to this web page here. To use the form, just enter your gear ratio and press enter. For example, if your gear ratio is 4672:1, enter 4672 and press enter.

The 2 dipswitches supplied with the Linistepper Kit are not used, and probably shouldn't be installed. The 2x5 header which normally carries step, direction and enable signals to the driver is used to select options, and can be connected to switches or just jumpered to the desired setting:

PORTA.F0 = INPUT_RUN run; (0v=run, 5v=stop) //normally the "STEP" input, on pin 5 of the header.

PORTA.F1 = INPUT_DIR motor direction; (0v=forward, 5v=reverse) // remains the "DIRECTION" input on pin 3.

PORTA.F2 = INPUT_SPEED selects speed 1 or speed 2; (0v=speed1, 5v=speed2) // normally the "ENABLE" input on header pin 1.

To connect switches, run one side of the switch to the pin listed above, and the other side to +5 logic power.

Custom chips available! Don't have a PIC programmer? Pre-programmed PIC's are now availabe, custom set to your gear ratio (be sure to specify your SPEED1 value when ordering). Resonator for use with V3 Linistepper kit also included.

See also:

• http://www.cnczone.com/forums/stepper_motors_drives/137484-drive_1_8_degree_stepper-5.html Thread that led to the development of this code.
• http://www.romanblack.com/LiniV2_temp/Lini_Telescope.c (cached 20120120) Source code in MikroC from mikroe.com
• http://www.mikroe.com/eng/products/view/7/mikroc-pro-for-pic/ C compiler for the source code. The project is small enough to compile in the free version.