Technical Data

In the following you can find a brief description of all connectors. If you need more information you can take a look in the schematics or in the KiCad development files of each product.

Stack Connectors

Each Brick has two connector types:

  • Stack Data Connector: Used for data exchange between Bricks.
  • Stack Power Connector: Powers the Bricks and attached Bricklets, motors, servos etc.

Stack Data Connector

Description Signal Pin Pin Signal Description
Stack SPI: MasterIn SlaveOut SPI-MISO 01 02 I2C-SDA/TDI Stack I2C: Serial Data/ JTAG-TDI
Stack SPI: MasterOut SlaveIn SPI-MOSI 03 04 I2C-SCL/TDO Stack I2C: Serial Clock/ JTAG-TDO
Stack SPI: Clock SPI-SCLK 05 06 SEL-0 Stack Select 0
Reset Signal RESET 07 08 SEL-1 Stack Select 1
Stack Detect/JTAG-TMS DETECT/TMS 09 10 SEL-2 Stack Select 2
Stack Synchronization/ JTAG-TCK SYNC/GP/TCK 11 12 SEL-3 Stack Select 3
Extension SPI: MasterIn SlaveOut EX-SPI-MISO 13 14 SEL-4 Stack Select 4
Extension SPI: MasterOut SlaveIn EX-SPI-MOSI 15 16 SEL-5 Stack Select 5
Extension SPI: Clock EX-SPI-SCLK 17 18 SEL-6 Stack Select 6
Extension 0: General Purpose 0/ Interrupt 0 EX-0-GP-0/nINT0 19 20 SEL-7 Stack Select 7
Extension 0: General Purpose 1/ Interrupt 1 EX-0-GP-1/nINT1 21 22 EX-SEL-0 Extension Select 0
Extension 0: General Purpose 2/ Interrupt 2 EX-0-GP-2/nINT2 23 24 EX-SEL-1 Extension Select 1
Extension 1: General Purpose 0 EX-1-GP-0 25 26 EX-SER-RXD Extension Serial Interface: RXD
Extension 1: General Purpose 1 EX-1-GP-1 27 28 EX-SER-TXD Extension Serial Interface: TXD
Extension 1: General Purpose 2 EX-1-GP-2 29 30 EX-SER-RTS Extension Serial Interface: RTS

All signals are 3.3V based.


  • Stack SPI: SPI bus communication between Brick and Master Brick.
  • JTAG: Debug Interface, shared with other signals. JTAG must not be used when a Brick is stacked together with others.
  • Reset: Signal to reset a Brick, routed through a stack such that all Bricks are reseted at the same time.
  • Stack Detect: Signal to detect the presence of a Master Brick. All Bricks except the Master Brick have the signals on top and bottom internally connected and check for a high signal (input pull-down) to detect stack operation. Master Bricks have two independent signals for top and bottom side. Each Master Brick sets the top signal output high and the bottom to input pull-down. If a low signal is detected on the bottom, the Master Brick will act as a master for the stack. If a high signal is detected, another Master Brick is below and will work as the master of the stack.
  • Stack Synchronization: This signal is used by a Master Brick to synchronize the actions of other Bricks in a stack.
  • Extension SPI The SPI bus for Master to Master Extensions communication.
  • Extension General Purpose 0,1: Three general purpose signals can be used by a Master Brick to control a Master Extension. The usage depends on the connected Master Extension.
  • Interrupt 0,1,2: Interrupt outputs, usage depends on configuration.
  • Stack I2C: I2C bus used by a Master to communicate with Master Extensions or to interface Bricks over I2C.
  • Select 0-7: Up to eight select lines can be used by a master of a stack to select up to eight Bricks in the stack. A Brick is only permitted to answer messages if it is selected (Select = low). Every Brick takes the first select signal of the bottom connector as its select. The other select lines are shifted, such that the second select signal of the bottom is the first select signal at the top, and so on. This method guarantees that the first eight Bricks on the top of a master have their own select lines. If more than eight Bricks would be connected to the master, only the lower eight Bricks can be selected and are able to communicate with the master.
  • Extension Select 0,1: Used by a master to select up to two Master Extensions. These lines are shifted by Master Extensions (working like select lines of Bricks). Hence the two lowermost Master Extensions stacked on top of a master can be used.
  • Extension Serial Interface: Used by a master to communicate with Master Extensions via a serial interface.

Stack Power Connector

Function Pin Pin Function
GND 21 22 5V
GND 23 24 5V
GND 25 26 5V
GND 27 28 3V3
Current 29 28 Voltage


  • PGND: Stack power ground signal.
  • PVCC: Stack power signal (max. 27V, 0.5A per pin, 5A in total), powered by Power Supplies.
  • GND: Common ground signal.
  • 5V: 5V power signal (max. 0.5A per pin, 1.5A in total), powered by every Brick (per USB) or Power Supplies. Since the USB voltage depends on your PC/USB hub, the 5V on this rail can not be guaranteed when powered over USB.
  • 3V3: Powered by every Brick. Created with on-board DC/DC converter (5V -> 3V3).
  • Current: Signal to measure the current flow created by Power Supply (max. 3.3V). Can be measured by Master Bricks.
  • Voltage: Signal to measure the voltage of an external power supply connected to a Power Supply (max. 3.3V). Can be measured by Master Bricks.

Bricklet Connector (10 Pole)

Pin Function Description
01 5V 5V signal, same as 5V in stack
02 GND Ground
03 3V3 3.3V generated by Brick
04 SCL I2C Serial Clock
05 SDA I2C Serial Data
06 ADDR Address line (low/high) used to select Bricklets for I2C communication
07 IO_1/AD I/O 1 with analog-to-digital capability
08 IO_2 I/O 2
09 IO_3 I/O 3
10 IO_4 I/O 4

When not otherwise stated, all signals are 3.3V based.

Bricklet Connector (7 Pole)

Pin Function Description
01 5V 5V signal, same as 5V in stack
02 GND Ground
03 3.3V 3.3V generated by Brick
04 CS SPI Chip Select
05 CLK SPI Serial Clock
06 MOSI SPI Master Output, Slave Input
07 MISO SPI Master Input, Slave Output

When not otherwise stated, all signals are 3.3V based.

USB Connector

Pin Function Description
1 VCC 5V
2 D- Data -
3 D+ Data +
4 GND Ground

The 5V power supply over USB has to be between 4.8V and 5.7V.