What is the LED Matrix RaspberrySTEM™ Cell?
It consists of:
-
A LED Matrix driver PCB – a circuit board,
that receives data from the Raspberry Pi, and displays
it on an LED Matrix using a small low-power
micro-controller (Atmel ATTiny48
-
An LED Matrix – a grid of LEDs, where for
each row the anode (positive-side) of the LEDs are
connected together. LED matrices can only show one
unique row of LEDs lit at one time, therefore the
micro-controller is required to sequence through each
row one at a time. This occurs faster than the eye can
perceive (through the eye's persistence of vision), and
therefore appears to be a solid image.
-
Communication from the Raspberry Pi to the LED
Matrix RaspberrySTEM™ Cell occurs over the SPI
bus
-
The SPI (Serial Peripheral Interface) is a common
interface for sending data between processors and other
ICs.
-
The micro-controller stores the brightness level of
each LED, on a scale from 0-15. In order to update the
full LED Matrix display, the Raspberry Pi must send 64
(i.e., 8 x 8) brightness levels, one for each LED, to
the LED Matrix RaspberrySTEM™ Cell.