Model Railway DCC Turntable Accessory Decoder for Arduino Nano – Kit Assembly Guide

Assembly Instructions

Model Railway DCC Turntable Accessory Decoder for Arduino Nano – Kit
DCCSC1.A4988.Kit.Nano

Package Contents

In your package you should find the following…

1 x PCB ( DCC Stepper Control Interface for Aruidno Nano)

1 x Pack 1 – DCC Interface

1 x 6n137 8 pin chip ( black or white in colour )

1 x 8 pin DIN socket

1 x Diode ( orange in colour )

1 x 1k Resistor

2 x 10k Resistor

2 x 10 pin female header

2 x 5 pin female header

1 x 2 pin screw terminal

1 x 3 pin screw terminal

1 x Pack 2 – Power Supply

1 x 7805 Voltage regulator

1 x 100uf 50v Cap

1 x 47uf 50v Cap

1 x 1uf 50v Cap

1 x 2 pin screw terminal

1 x Pack 3 – A4988

1 x A4988 Control daughter board

2 x 8 pin female header

2 x 5 pin male header

2 x 2 pin screw terminal

Assembly.

The assembly is split in to 3 parts – [Pack 1 – DCC Interface], [Pack 2 – Power Supply], and [Pack 3 – A4988].

Take time to make yourself familiar with the parts and where they should go.

Pack 1 – DCC Interface

Taking the parts from Pack 1 – assemble the DCC Interface by soldering the parts to the PCB as follows

Step Action
1 Solder the 8 pin DIN socket to the PCB
2 Solder the two 10k resistors to R1 and R2, following the PCB image as an orientation guide ( horizontal )
3 Solder the Diode to the PCB, making sure the BLACK ring is at the top. This is important.
4 Solder the single 1k resistor to R3, following the PCB image as an orientation guide ( vertical )
5 Solder 1 of the 10 pin and 5 pin female headers to the top row of the Arduino Nano (v3) holes.
6 Solder the other 10 pin and 5 pin female headers to the bottom row of the Arduino Nano (v3) holes.
7 Solder the 3 pin screw terminal so that the wire input holes are facing outwards ( I/O GND and PWR )
8 Solder the 2 pin screw terminal so that the wire input holes are facing outwards ( DCC )
9 Push the 6n137 chip in to the 8 pin DIN holder, pin 1 top left corner ( signified by a dot on the chip ). You may need to align the pins in order to make it fit.

This completes the first part and should look like this – notice the diode has its BLACK STRIP at the top.

Part 2 – Power Supply.

The power supply circuit is designed to take power from a 12 – 16v DC supply and convert it to 5v for the logic circuit.

Step Action
1 Solder the 2 pin screw terminal so that the wire input holes are facing outwards ( downwards ) ( – + )
2 Solder the 100uF 50v Cap in position above the 2 pin screw terminal soldered in step 1. The negative terminal of the cap is on the left.
3 Solder the 47uF 50v Cap in the position to the right of the A4988, and above the 7805. The negative terminal of the cap is on the top.
4 Solder the 7805 voltage regulator so the top pin is the voltage in, the middle is GND and the bottom pin is the voltage out ( 5v ). This will usually mean the heat sink is on the right facing the edge of the board.
5 Solder the 1uF 50v Cap below the 7805. The negative terminal of the cap is on the bottom.

This completes the second part and should look like this – notice the cap orientations, and which way the 7805 is facing.

Pack 3 – A4988

The last pack is the A4988 daughter board and the connections for the stepper motor.

Step Action
1 Solder one 2 pin screw terminal on the left so that the wire input holes are facing outwards ( downwards ) ( 1B 1A )
2 Solder one 2 pin screw terminal on the right so that the wire input holes are facing outwards ( downwards ) ( 2A 2B )
3 Solder 1 of the 8 pin female headers to the top row of the A4988 holes.
4 Solder the other 8 pin female headers to the bottom row of A4988 holes.
5* Solder the 2 – 5 pin male headers above the A4988 holes

This completes the second part and the whole board should look like this – I have plugged an Arduino Nano in already..

A4988 Information.

The A4988 is a stepper motor controller by Pololu. You can find a wealth of information on their website https://www.pololu.com/product/1182 including how to connect a stepper motor.

*WARNING*

Never connect or disconnect a stepper motor while the A4988 is powered – damage can be caused to the A4988. ALWAYS DISCONNECT POWER from the A4988 ( remove the power source ) when connecting or disconnecting the stepper motor.

Here is a pin out of the A4988

https://a.pololu-files.com/picture/0J3360.600.png?d94ef1356fab28463db67ff0619afadf

Here are the connections from the A4988 to the Arduino.

A4988 Pin Arduino Pin Purpose
STEP D4 Control the step of the stepper motor
DIR D5 Control the direction of the stepper motor
ENABLE D6 Enable the Stepper Motor
VDD +5v Logic Power supply
GND GND Ground

The last column of pins above the A4988 are designed to allow the user to set the five different microstep resolutions (down to 1/16-step).

https://www.dfrobot.com/wiki/images/thumb/8/80/DRi0023_resolution.png/400px-DRi0023_resolution.png

The top row of the 5×2 pin headers are connected to +5v. the bottom row are connected to the A4988 pins ( Sleep, Reset, MS1, MS2, MS3 and Enable ). With no jumpers connected, MS1, MS2 and MS3 are in the LOW position ( in relation to the above table ). To set a MicroStepping to high, use a jumper to connect the A4988 pin to +5v – hence making it HIGH.

E.g. for Eighth Step – place a jumper on MS1 and 5v , and MS2 and 5v. For Full steps, place no jumpers.

Important : Make sure there is a jumper between the SLEEP and RESET pins.

This completes the assemble of the kit. I hope you had fun building it.

Please fully read the Pololu product web page, and the FAQ here… https://www.pololu.com/product/1182/faqs