|Model Railway DCC Turntable Accessory Decoder for Arduino Uno (R3) – Kit|
In your package you should find the following…
1 x PCB ( DCC Stepper Control Interface for Aruidno Uno (R3))
1 x Pack 5 – 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 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 2 pin male header
1 x A4988 Control daughter board
2 x 8 pin female header
4 x 2 pin male header
2 x 2 pin screw terminal
The assembly is split in to 3 parts – [Part 1 – DCC Interface], [Part 2 – Power Supply], and [Part 3 – A4988].
Take time to make yourself familiar with the parts and where they should go.
Part 1 – DCC Interface
Taking the parts from Pack 5 – assemble the DCC Interface by soldering the parts to the PCB as follows
|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. Pay attention to the orientation of the caps.
|1||Solder the 2 pin screw terminal so that the wire input holes are facing outwards ( to the left ) ( – + )|
|2||Solder the 100uF 50v Cap in position to the left of A4988|
|3||Solder the 47uF 50v Cap in the position above the 100uF CAP|
|4||Solder the 7805 voltage regulator so the top pin is the voltage out ( 5v ), the middle is GND and the bottom pin is the voltage in. This will usually mean the heat sink is on the left facing the edge of the board.|
|5||Solder the 1uF 50v Cap to the left of the 7805.|
This completes the second part and should look like this – notice the cap orientations, and which way the 7805 is facing.
Part 3 – A4988
The last part is the A4988 daughter board and the connections for the stepper motor.
|1||Solder one 2 pin screw terminal on the right so that the wire input holes are facing outwards ( to the right ) ( 1B 1A )|
|2||Solder one 2 pin screw terminal on the right so that the wire input holes are facing outwards ( to the right ) ( 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 3 – 2 pin male headers on the far left of the board|
This completes the second part and the whole board should look like this
- If you want to power the board from the power source, solder a 2 pin male header top right, and use a jumper.
The A4988 needs to be installed so that the current adjusting “pot” is facing to the right – towards the Motor connections.
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.
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
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|
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).
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