Explore ATtiny Microcontrollers using C and Assembly Language Power Supply A 5V DC (Direct Current) power supply capable of delivering 100mA or more is needed to power AVR breadboard circuits. Many different power supplies are available, such as the breadboard power supply shown in Figure 0.4. An external power supply may not be needed if using a hobby programmer, as they usually supply 5V from USB. There are many different breadboard power supplies available. The one shown in Figure 0.4 is just one example and is manufactured by RobotDyn. It can supply 1A of current at 5V and 800mA of current at 3.3V. The two voltages are individually selectable by jumpers on the board. This means that one rail can be set to 5V and the other to 3.3V for circuits that use both 5V and 3.3V, but only 5V is needed with this book. This breadboard power supply requires an external DC supply of 6V to 12V supplied on the barrel connector. A mains voltage to 12V DC power supply is shown in Figure 0.4 supplying 12V DC to the breadboard power supply via a 2.1mm centre positive barrel connector. If you are using a different make or model of breadboard power supply, be sure to check its specifications and configuration from the manufacturer.
Figure 0.4: 5V/3.3V Breadboard Power Supply Powered by an External DC Supply
On most of these breadboard power supplies, the USB connector is intended as a 5V output for USB powered devices. Some of them allow 5V to be fed into this connector to
26
