Atmel AVR10004: RCB256RFR2 – Hardware User Manual [APPLICATION NOTE]
8
4.
Functional Description
illustrates the RCB setup in general. It mainly consists of an Atmel ATmega256RFR2 and some peripheral
circuitry. An ID EEPROM stores MAC address and additional board information. This information is stored in a separate
EEPROM to avoid accidental data erasure during microcontroller firmware development.
Figure 4-1. Radio controller board - block diagram.
The radio transceiver incorporates MAC hardware accelerators to handle all RF modulation/demodulation, signal
processing, and frame reception and transmission actions. Further information about the radio transceiver and the
microcontroller are provided in the datasheet (see reference
The RF front-end implementation was kept minimal by using a balun with integrated filter. An antenna, provided with the
RCB, has to be connected to the SMA connector.
All components are placed on one PCB side to demonstrate a low-cost manufacturing solution.
4.1
Power supply
The RCB is powered by a single supply voltage in the range of 1.8V to 3.6V, which makes it possible to use 1.5V
alkaline cells. Optionally, the power can be supplied from a base board. In this case, the power switch, SW1, must be in
the off position or the battery must be removed from the battery holder.
All PCB components are powered by this single supply to minimize the bill of materials (BOM) and maximize the power
efficiency.
4.1.1
Battery power
For autonomous operation, the RCB can be powered by two AAA batteries inserted in the battery clip on the back side
of the RCB. Use power switch SW1 to manually switch on/off the board.
Note:
A power cycle may not be detected if the radio transceiver and microcontroller are in sleep mode with all peripheries
disabled.
4.1.2
External power
An RCB mounted on a base board may be powered via the expansion connectors (see
). In this case, the
power switch, SW1, has to be in the off position to avoid unintentionally charging the batteries, if present.
32kHz
16MHz
ATmega256RFR2
Expansion
Connector
1
ID
EEPROM
LEDs
Pushbutton
Expansion
Connector
2
Filter-Balun
