V4 2018

PicGoto Step-dir Telescope Controller (V4 2018) for bipolar steppers

DIY Goto telescope controller based on Angel Caparros's PicGoto system.

Features

• PicGoto firmware for bipolar stepper motors (Step-dir version)
• USB-TTL (PL2303 modified adapter, see HERE!), Bluetooth (HC-06), WiFi (ESP-01 here) and Hand Remote Controller (with D1-mini, here)
• SkySafari interface in WiFi mode
• DRV8825/A4988/LV8729 stepper drivers support
• Overcurrent protection with fuse
• Switches for TTL/BT/WiFi use with control LEDs
• Auxiliary and Focus steppers support
• Internal ventilation fan
• 9-24V power input

Hardware list

• Step-down AMS1117 module 5V to 3.3V
• Step-down buck converter (main power to 5V)
• LED metal holder (x3)
• RJ9 4P4C Right Angle Connector (x3)
• XH2.54 Header Connectors (2 pins x5, 3 pins x1, 4 pins x1))
• Socket 18-pins (x3)
• Header socket 2x4
• DC Power Jack
• Slider switch 2 positions, 3 pins (x2)
• Slider switch 3 positions, 8 pins (x2)
• Plastic case
• PIC16F648A PIC MCU (x2)
• Fuse
• Fuse holder
• Crystal oscillator 20MHz (x2)
• Electrolytic capacitor 100uF 50V (x2)
• Ceramic capacitor 22pF (x2)
• Fan 30x30 5V
  • 5V LEDs with resistors (x3)
  • Gerber files available for online PCB printing, e.g. EasyEDA (download at the bottom of current page)

Main components list (schematic available in Image Gallery)

Resistors

• R1,R2 (value depends on stepper motor characteristics)
• R3 1K (pull-up for HC-06)
• R8, R16, R17 LED’s resistors (value depend on LED characteristics, 470Ω-2K)
• R10 10K (pull-up for ESP-01)
• R11 10K (pull-up for ESP-01)
• R12 1K (voltage divider for HC-06)
• R13 2K (voltage divider for HC-06)

Capacitors

• C5,C6 22pF, ceramic
• C7,C8 100µF, 25V, electrolytic

Diodes

• D1 1N4007
• D2 Schottky 1A
• D3,D4 BAT42

ICs

• RA, DEC PIC16F628A
• IC3 ULN2803

XTAL

• Q1,Q2 20MHz

Driver boards

• DRV8825/A4988/LV8729 (2)

The power input is DC 9-24V and regulated internally by two DC-DC step-down buck modules, one converting Vin to 5V for MCUs, HC-06, Fan and LEDs and the other converting 5V to 3.3V for ESP-01.

On one side of the box you can find two switches beside the control LEDs, the Main Power switch and a switch that activate/deactivate the fan.

Below the LEDs, the two 3-positions small switches that set I/O data mode. Set the switches on the left position if you want Bluetooth mode or set them to the right if you decide for WiFi mode. The switch on the left side controls the data signals while the switch on the right side turns on/off the corresponding module board.

I designed the PCB with Fritzing and the exported Gerber files are available for download here below at the bottom of this page.

Please, be careful connecting the Step-down modules as shown below.

Explore my image gallery for more images of the controller and accessories.

WARNING:

Before using the USB-TTL RJ9 connector jack read carefully this page!

Update February 2020

Error in PCB corrected, new Fritzing and Gerber files available (Gerbers not tested). The 2018 version can be updated with a simple bridge, as shown here below (thanks Joaquin).

pierluigi.giorgi@gmail.com

December 2018