OnStep Version : The current stable release is recommended. Some older versions may also work.
4.x (recommended)
3.x
Mount Type : Dobsonians will almost always be Alt-Azimuth, unless they are on an equatorial platform.
Equatorial
Alt-Azimuth
Fork
Board : Which board will you be using for OnStep? Check the Wiki for more details on the capabilities,
and complexities of each one.
MiniPCB v1
MiniPCB v2
MaxPCB v1
MaxPCB v2
MaxSTM v3
FYSETC S6 v1.2
FYSETC S6 v2.0
STM32 Blue Pill PCB
WeMos R32 + CNC V3
MKS Gen-L v1 (NOT recommended)
MKS Gen-L v2
MaxESP v2
MaxESP v3 or MiniESP v3
RAMPS 1.4/1.5 (NOT recommended)
Desired Slewing Rate [SLEW_RATE_BASE_DESIRED From the spreadsheet].
This is desired slewing rate in degrees per second. This value will be adjusted by OnStep to what the
microcontroller can handle. Decimal value allowed.
Steps Per Worm Wheel Rotation [AXIS1_STEPS_PER_WORMROT from the spreadsheet].
This is the number of steps per full rotation of the worm gear. Must be an integer .
Applies only to Equatorial Mounts , and only if you will be using Periodic Error Correction (PEC).
If you will not be using a PEC sensor, then set this value to zero.
Axis 1
Axis 2
Stepper motor steps per rotation [Stepper-Steps from the spreadsheet].
This does not include any gear box attached to the motor.
200 steps, 1.8°/step
400 steps, 0.9°/step
100 steps, 3.6°/step
96 steps, 3.75°/step
48 steps, 7.5°/step
24 steps, 15°/step
200 steps, 1.8°/step
400 steps, 0.9°/step
100 steps, 3.6°/step
96 steps, 3.75°/step
48 steps, 7.5°/step
24 steps, 15°/step
Microsteps [Micro-Steps from the spreadsheet].
This is microstep when the motors are tracking. Note that different steppers driver models support different
stepping ranges. More validation will be done when you use the config file from this generator to build the
OnStep firmware.
1
2
4
8
16
32
64
128
256
1
2
4
8
16
32
64
128
256
MICROSTEPS_GOTO (not in the spreadsheet!)
This is the microstep value when the motors are slewing. This value depends on several factors, including: the
specific microcontroller used, whether the board is wired up to allow on-the-fly microstepping mode change, the
stepper driver model, ...etc. If your spreadsheet has a reasonable slewing rate, then start with 'Off' initially.
If you find that the value in the spreadsheet causes slow slewing, then experiment with having a different value
here than what is in the microsteps for tracking.
More validation will be done when you use the config file from this generator to build the OnStep firmware.
Off
1
2
4
8
16
32
64
128
256
Off
1
2
4
8
16
32
64
128
256
Transfer gears/pulleys ratio [GR1 from the spreadsheet].
This is the overall ratio of any gears or pulleys that transfer motion from the motor to the main worm gear of the
telescope. Use 1 if the motor is directly coupled to the worm wheel. This value can be fractional .
Worm wheel gear ratio [GR2 from the spreadsheet].
This is the number of teeth on a worm wheel that is coupled to the worm gear. Must be an integer .
Values for some common mounts can be found here
and here .
Stepper Driver Model: This is the specific model for the driver that you will be using for each axis.
The recommended drivers are: LV8729, TMC2130, TMC5160, TMC2209. Note that the drivers denote with a †
sign have some limitations. For example, the DRV8825 causes vibrations, and the A4988, TMC2208, and TMC2100
have limitations in their microstepping range. You must make sure your board is compatible with the driver
that you choose here.
LV8729
TMC5160
TMC5160 Quiet
TMC2130
TMC2130 Quiet
TMC2209
S109
External
TMC2100 †
A4988 †
DRV8825 †
TMC2208 †
LV8729
TMC5160
TMC5160 Quiet
TMC2130
TMC2130 Quiet
TMC2209
S109
External
TMC2100 †
A4988 †
DRV8825 †
TMC2208 †
Stepper Driver Tracking Current (IRUN): This only applies to TMC SPI Silent StepSick drivers.
Specifically, the TMC5160, and the TMC2130 (provided that the latter's potentiometer is set to the maximum of 2.5V).
This is in milliamperes (mA), and when the mount is tracking. You can edit the Config.h file later for finer adjustment.
For all other driver models, this must be OFF.
Off
400
600
700
800
900
1000
1200
Off
400
600
700
800
900
1000
1200
Stepper Driver Slewing Current (IGOTO): This is only applies to TMC SPI Silent StepSick drivers.
Specifically, the TMC5160, and the TMC2130 (provided that the latter's potentiometer is set to the maximum of 2.5V).
This is in milliamperes (mA), and when the mount is slewing. You can edit the Config.h file later for finer adjustment.
For all other driver models, this must be OFF.
Off
400
600
700
800
900
1000
1200
Off
400
600
700
800
900
1000
1200
Reverse motor direction for this axis? This is useful if you find the motors moving the
opposite direction of what you want, and don't want to change the wiring.
No
Yes
No
Yes
Step Wave Form: Depending on the board and stepper driver model, using PULSE wave form can speed slewing
by up to 60% over regular SQUARE. If you are unsure, leave this unchanged.
Normal (Square)
Pulse
Time/Location Source: Whether there is a module that provides the time and/or location, such as a GPS module, or
a Real Time Clock (RTC). This is useful to compensate for the imprecise ceramic crystal on some boards, and to
provide the time/date and the location automatically, without having to enter all that manually.
You need to connect the Square Wave pin (SQW) on the module to the PPS pin on board. For STM32 boards without
a built-in EEPROM, an I2C RTC with an EEPROM is required, such as the DS3231 module.
None
DS3231 I2C
DS3234 SPI
GPS Module
Buzzer: If you have a buzzer, OnStep can indicate certain events, such as the start of a slew, and arrival
to target. Choose from Active buzzer (i.e. fixed tone), Passive buzzer with either 1 kHZ or 2 kHz, or None for no buzzer.
None
Active
Passive: 1 kHz
Passive: 2 kHz
Automatically Start Tracking : Upon startup, should OnStep start sidereal tracking automatically? Valid only for
Equatorial and Fork mounts.
This should only be set to Yes for initial testing, until you get the controller fully working, and you are familiar
with OnStep's startup procedure (N-Star Alignment). It should also not be used if the scope will be parked/unparked.
No
Yes
Will you be using the ST4 Port for guiding only, or for a Smart Hand Controller as well?
Disabled
Guiding only
Pullup resistors, for SHC
Will you be using an ST4 Hand Controller ? If so, set this to Yes, otherwise, choose No.
No
Yes
PEC Sensor Do you have an index sensor on the RA worm gear? This can be a Hall Effect or Optical Interrupt sensor.
No
Yes
Limit Sense: Will you be using one or more switches to detect limits? For example, to prevent the optical tube from hitting
the mount, pier or tripod?
No
Yes