Technical Data¶

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.

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.