User manual

049 delay(5);
050
051 }
DIGITAL VOLTMETER
WITH BAR CHART DIS-
PLAY AND USB INTER-
FACE
With what you have learned so far, you can now program a digital
Voltmeter with analogue bar chart display. The bar chart display
will be valuable for setting work. You can see much more precisely
where, e.g., the maximum or minimum is, on an analogue display
than on a digital display with pure numeric output. As a special
feature, we supplement the program with a serial output that will
send your measured data to the PC via the USB interface. Here,
we use the USB- interface already present on the Ar-
duino™-UNO-board that we are already using for programming.
Resistors R1 and R2 are not needed in this experiment and are
not enclosed with the learning package! They will, however, be
further explained in this chapter. If you need them, you can
purchase them in a specialist electronics store later.
You can use the circuit to measure very precise voltages between
0 and 5 V using the analogue input A0 without the two resistors
R1/R2. However, ensure that you do not connect any higher
voltages to the connection, since the Arduino™-board would be
damaged by this. You may already measure the voltage of one or
two Mignon cells (AA) or Micro cells (AAA) extremely precisely
with the circuit. The example is very similar to that of the
photometer, but with a few different details. This time, we also
use the serial interface (UART = Universal Asynchronous Receiver
Transmitter) of the Arduino™-micro controller. The measured data
are sent through the serial interface of the micro controller
(UART) to the UART-to-USB-converter on the Arduino™-PCB , which
passes it on to the PC. The serial connections D0/RX and D1/TX
are already firmly connected to the converter and no further