1 In this article
By this article, we will show schematic of ChibiCube in order to understand how it works and hot it has been designed.
2 Toward ChibiCube schematic
As mentioned in the previous article, ChibiCube addresses all its LEDs through the combination of anode and cathode signals. Each floor of the cube is configured as common anode, while the various cathode signals are separately connected to the outputs of the Shift Register. Setting the anode voltage to a value equal or greater than the high logical threshold of our SR, for the same principle illustrated in the tutorial Meeting SPI, we can address single LEDs of the floor. To make it simple, consider a cube 4x4x4: the diagram of a single floor would appear as in Fig.1.
This schematic is different from the one shown in SPI tutorial in some points:
- The SR is a 16 bit one and is a LED driver. Output current is fixed choosing R-EXT and we don’t need for a resistor on each LED;
- To make schematic simple, LEDs are oriented as a 4×4 matrix;
- The common anode is addressed by MCU thought a P-MOS, instead being connected directly to power supply;