2

AVR4013

8349A-AVR-11/10

2 Schematics

C1

DC

TOSC1

TOSC2

TX

9

10

3

VCC

GND

ATMega88PA

32kHz

UART

R1

0010010101110….

Figure 2-1. picoPower demonstration schematics

From Figure 2-1 we can see that the demonstration circuit is quite simple. We have a

DC source set at 5.5V, which is used to charge the capacitor when the switch is

pushed. When the switch is released, the ATmega88PA will run off the energy stored

in the capacitor, C1. The main clock source for the device is the internal RC oscillator.

Timer 2 is connected to an external crystal and will work in asynchronous mode to be

able to function in some of the sleep modes which we will make use of in the

demonstration.

3 The code

The code is meant to simulate a sensor device that transmits data once a second.

After the initialization (which will differ with each optimization method), the code will

enter an infinite loop.

This loop is separated into stages:

ADC conversion

Simulated 1000 cycles of processing

Convert number in to ASCII string

Send data over UART (More oomph to your amps, picoPower! [iteration nr])

Repeat

The loop will start by doing one ADC conversion to simulate data gathering from

some analog device. Then the device will enter a function that simulates 1000 cycles

of data processing. In many applications, converting a number to its ASCII

representation is preferred, and so we convert the iteration count of the loop to ASCII.

Finally, we send the string “More oomph to your amps, picoPower! [iteration count]”

over the UART. Then the loop repeats.