The Matrix (CPU Utilization)
Aside from the doubled RAM capacity, one of the main attractions of the new Raspberry Pi 2 is the four CPU cores: four times the brain power! In this chapter, we’re going to look at a few ways to visualize the CPU activity present in the cores.
The LED Matrix
There is available an 8 × 8 matrix array of red LEDs that can be purchased at low cost. To make it easy to drive these, there is also the MAX7219 LED display driver IC. You could build it yourself, but these are available as an assembled or unassembled pcb kit. The one shown in Figure 3-1 was purchased on eBay assembled for $2.24 (free shipping). ...