The divider outputs a voltage equal to two-thirds of the battery voltage, which will always be safely below the
Arduino’s maximum analog input voltage of 5 V. For example, at a battery voltage of 4.8 V, analog pin 1 will be
at a level of 3.2 V. Using Arduino’s
analogRead()
function, where 5 V is read as a value of 1023, 3.2 V is read as
a value of 655. To convert it back to the actual battery voltage, multiply this number by 5000 mV×3/2 and divide
by 1023:
unsigned int batteryVoltage = analogRead(1) * 5000L * 3/2 / 1023;
• The
buzzer control jumper
connects one of the Arduino’s PWM outputs to the buzzer on the Zumo
Shield. This jumper is disconnected by default.
If you have an Arduino
Uno
or an older Arduino (with an ATmega328P or ATmega168 microcontroller), you
should jumper the two holes bracketed with the label
328P
to connect the BZ pin to digital pin 3. If you have
an Arduino
Leonardo
(with an ATmega32U4 microcontroller), you should jumper the two holes bracketed
with the label
32U4
to connect the BZ pin to digital pin 6. These are the pins our
[http://www.pololu.com/docs/0J57/6]
expects the buzzer to be connected to for each respective microcontroller. More
details about the buzzer can be found in
• The
compass I²C jumpers
connect the I²C clock (SCL) and data (SDA) lines of the LSM303DLHC
3-axis compass module on the Zumo Shield to the SCL and SDA pins on the Arduino. These jumpers are
connected by default, but can be disconnected by cutting the thin trace between each pair of holes.
On the Arduino Uno R3, SCL and SDA are duplicates of analog pins 5 and 4, respectively. On the Arduino
Leonardo, SCL and SDA are duplicates of digital pins 3 and 2, respectively. Using the LSM303 on the shield will
prevent these pins from being used for other purposes, and the I²C pull-up resistors will affect readings on these
pins even if the compass is not being actively used, so you must cut the jumpers to disconnect the LSM303 and
pull-ups if you want to repurpose the SCL and SDA pins.
Please note that the SCL and SDA pins do not exist on Arduino hardware versions prior to the Uno R3, so you
will have to manually connect SCL to analog pin 5 and SDA to analog pin 4 on the Zumo Shield in order to use
the compass with an older Arduino. The most convenient place to do this is in the front expansion area, where
these pins are all located together, as indicated by the light blue boxes in the picture above.
More details about the 3-axis compass module can be found in
Instead of making a wire connection, you can solder a 1×3 male header to the buzzer control
jumper holes to allow the use of a shorting block for connecting the buzzer. You can also use
male headers and shorting blocks for the battery level jumper and compass jumpers if you have
an Arduino Leonardo or an Arduino Uno with an SMD (surface mount) microcontroller. However,
there is not enough clearance to use male headers on the battery level and compass I²C jumpers if
you are using an Arduino with a DIP (through-hole) microcontroller.
3.d. 3-axis compass module (accelerometer and magnetometer)
The Zumo Shield includes an onboard
[http://www.pololu.com/catalog/product/2124]
compass module
that combines a 3-axis accelerometer and 3-axis magnetometer into a single package with an I²C interface.
This sensor can be used in advanced applications to help your Zumo detect collisions and determine its own
orientation. We recommend carefully reading the
[http://www.pololu.com/file/download/
(629k pdf) to understand how it works and how to use it.
Pololu Zumo Shield for Arduino User's Guide
© 2001–2012 Pololu Corporation
3. The Zumo Shield in detail
Page 20 of 28
