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Revision as of 17:23, 7 June 2013 by Adrianbowyer (talk | contribs) (Melzi Arduino Pin Numbers)
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Release status: working

Release Version 2.0
CAD Models
External Link


A compact all-in-one controller board for RepRaps with one extruder head, optimized for mass production.

The point of RepRap is to make itself, of course. But sometimes people just want plug-and-play RepRap electronics so they can concentrate on the other aspects of the machine, or just because they are more software or mechanics oriented than electronics oriented.

Melzi is designed to be a complete set of RepRap electronics that should be very cheap to mass produce. It was originally based on the Arduino Leonardo (Francesco Melzi was Leonardo's pupil).

Melzi Version 2.0



  1. Processor: ATMEGA1284P (Sanguino compatible)
  2. All screw connectors - no soldering
  3. Micro SD card slot for GCode files
  4. Mini USB interface
  5. 4 x A4982 stepper drivers
  6. 3 x MOSFET drivers for hot end, bed and cooling fan
  7. Dimensions: 210mm x 50mm x 17mm
  8. Weight: 70g




Version 2.0 of Melzi was developed from Joe Mosfet's original by RepRapPro Ltd. It can be found at:

Bootloader and Firmware Upload

There is a version of the Marlin RepRap firmware for Melzi on RepRapPro Ltd's Github repository here. It contains the extra files needed for the Arduino IDE to talk to a Sanguino (and hence to the Melzi). These also allow you to flash the bootloader using an appropriate programmer.

There are more detailed firmware instructions on the RepRapPro site here and on this Wiki here.

Melzi Arduino Pin Numbers

#define X_STEP_PIN         15
#define X_DIR_PIN          21
#define X_MIN_PIN          18

#define Y_STEP_PIN         22
#define Y_DIR_PIN          23
#define Y_MIN_PIN          19

#define Z_STEP_PIN         3
#define Z_DIR_PIN          2
#define Z_MIN_PIN          20

#define E0_STEP_PIN         1
#define E0_DIR_PIN          0

#define LED_PIN            27

#define FAN_PIN            4 

#define HEATER_0_PIN       13 // extruder

#define HEATER_BED_PIN     10 // bed (change to 12 for breakout pin on header)
#define X_ENABLE_PIN       14
#define Y_ENABLE_PIN       14
#define Z_ENABLE_PIN       26
#define E0_ENABLE_PIN      14

#define TEMP_0_PIN          7   // Analogue pin
#define TEMP_BED_PIN        6   // Analogue pin
#define SDSS               31

#define SLAVE_CLOCK	   16

Melzi with Bluetooth

In order to get rid of the USB connection between Melzi and the PC one may like to use Bluetooth. There is a cheap module available in the market called 'JY-MCU' (vendor Shenzhen Jiayuan Electronic Co.,Ltd.). Jy-mcu f.jpg Jy-mcu b.jpg

Change setting

Before the module can be used the default setting has to be changed. Connect the module from PC via USB<->RS232 (RxD/TxD) interface with default settings (9600, N, 8, 1). The module shouldn't be paired at that moment. Apply with a terminal program the following AT commands:

AT+BAUD8 OK115200BAUD (set baud rate for Melzi)
AT+NAMEHUXLEY OKsetname (optional set name, default: linvor)
AT+PIN0000 OKsetPIN  (optional set pin, default: 1234)

More details about the configuration you will find here [[1]]


On Melzi one of the unused buffer of soldered 4050D takes over the mandatory level-shifting (5V -> 3.3V). Overall only 5 wires have to be soldered.

BT Connection.png

Connect via Bluetooth

Once you have setup your BT devices you can select from drop down list and control your RepRap as usual.