Before using this configuration generatior, you have to do the following:

By using this generator, you confirm that you have done the above! Use at your own risk!

Please provide feedback on this online configuration generator, so it would be continually improved.

Configuration Parameters

Mount Type. Dobsonians will almost always be Alt-Azimuth, unless they are on an equatorial platform.
Which board will you be using for OnStep? Check the Wiki for more details on the capabilities, and complexities of each one.
MaxRate [From the spreadsheet].
This is the number of microseconds between pulses to the motors when they are slewing. The lower the value, the faster the microcontroller is pulsing the motor, the faster the slew speed, in degrees per seconds. Different microcontrollers have a different lower limit (as per the spreadsheet). You can use a significantly lower value than the spreadsheet, but only if you select a value for "MICROSTEPS_GOTO" (i.e. mode switching), thus increasing the slewing speed considerably. To do this, there are other factors involved, including your board, motors, gears and stepper drivers, and therefore you need to experiment before arriving at an ideal value. Also, if you find there is resonance in the motors making them too noisy, or that they are stalling (whining sound with no movememnt), then lower MaxRate. Must be an integer.
PEC Buffer Size [PECBufferSize from the spreadsheet].
Applies only to Equatorial Mounts. This is also known as the 'worm period', and is the number of seconds for a full rotation of the worm gear. Must be an integer.

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.
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.
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, the stepper driver model, ...etc. If your spreadsheet has a reasonable slewing rate, you may want to start with 'Off' initially, and only test other values later. If you find that the value in the spreadsheet is slow, then experiment with having a value for Microsteps when slewing. More validation will be done when you use the config file from this generator to build the OnStep firmware.
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 wheel of the telescope. Use 1 if the motor is directly coupled to the worm wheel. This value can be fractional.
Worm wheel steps per full rotation [GR2 from the spreadsheet].
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.
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.
Real Time Clock (RTC). This is useful to compensate for the imprecise ceramic crystal on the Mega2560 boards. You need to connect the Square Wave pin (SQW) on the RTC to the PPS pin on the Mega. For STM32 boards without a built-in EEPROM, an I2C RTC with an EEPROM is required, such as the DS3231 module.
Buzzer type. 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.
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.
Enable Focuser? Enable one or both focusers if you have them attached. Otherwise choose None.
Will you be using the ST4 Port for guiding only, or do you have pullup resistors as well?
Will you be using an ST4 Hand Controller? If so, set this to Yes, otherwise, choose No.
When using a hand controller, what will pressing the [N]+[S] buttons do? This can be either Catalog mode or Focuser mode.
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?
BME280 Temperature, Humidity and Pressure sensor, for refraction compensation. These are used to calculate better refraction compensation.
Remember Auto Meridian Flip between power downs?

After you have filled all the above values, click the button below to generate your Config.x.h file.

Note: the generated file should overwrite the one by the same name that you got in the .zip file of OnStep.