Atmel AVR2016, User Manual

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Atmel AVR2016: RZRAVEN Hardware User’s Guide [APPLICATION NOTE]
8117E − AVR − 07/12
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2.6
Microphone
The Atmel AVRRAVEN’s microphone is connected to the Atmel ATmega3290P ADC channel 0. The signal is amplified
and low-pass filtered. Pulling PORTE7 low activates the microphone circuit.
2.7
Serial Dataflash
A 16Mb Atmel Serial Dataflash (AT45DB161D) is connected to the ATmega3290P’s Serial Peripheral Interface (SPI).
This storage is used for safe firmware images, sounds and general-purpose parameters. See the firmware
documentation for an overview of occupied sectors, and those available to the end user. Even with a couple of safe
firmware images for the two microcontrollers there is plenty space left for the end user. Please note that the serial
Dataflash will operate properly when the voltage is above 2.5V while the rest of the design will operate down to 1.8V.
2.8
Serial EEPROM
A 2kb Atmel Serial EEPROM (AT24C02B) is connected to the Atmel ATmega1284P’s two-wire interface (TWI). This
storage is write protected by hardware and can only be read. The storage contains important configuration and
calibration data that should not be unintentionally overwritten. Information such as a unique EUI 64-bit address can be
found her-in. A rich set of access functions and the parameter map is given in the RZRAVEN firmware documentation.
2.9
Real Time Clock
Separate 32768Hz clock crystals are connected to the ATmega3290P’s and the ATmega1284P’s asynchronous timer
interfaces. This allows an application to implement a real time clock (RTC) to keep track of time when sleep modes are
used to reduce the power consumption. This is especially important for battery-operated nodes.
2.10
NTC
An NTC is connected to the ATmega3290P’s Analog to Digital Converter (ADC) channel 4. This NTC can be used to
measure the temperature in the surroundings of the AVRRAVEN. The NTC can be found below the joystick, close to
J401. The JTAG interface must be disabled when using the temperature sensor. When running the AVRRAVEN from
an external power source the onboard voltage regulator may heat the temperature sensor giving faulty reading. To
avoid this the sensor NTC may be soldered off and relocated using short wires. If a higher level of accuracy is required
the users may also calibrate the sensor by adjusting the temperature lookup table in firmware.
2.11
Power supply
The AVRRAVEN can be powered either from batteries or an external 5V to 12V DC source. The power source is
selected by the position of the jumper located immediately to the right of the LCD (See
Figure 2-3 for a reference).
Polarity protection is provided when using an external power source.