User's Manual

AVR2044

8339A-AVR-09/10

Any crosstalk from digital lines into the crystal signals increases the phase noise, and

reduces the radio transceiver performance.

A grounded guard trace is placed around the crystal area to protect the crystal

against digital noise.

To investigate the impact of digital noise on the reference crystal, it’s recommended

to perform packet error rate tests with potential digital noise sources enabled and

disabled. The influence of disturbances such as MCLK or SPI activity during transmit

or receive can be evaluated by comparing the measurement results.

5.7.8 PCB Detail 8 – RF Section Shielding

A shield covering the Atmega128RFA1 and related parts is used to protect the IC

from external noise and strong interferers. The shield is not required to suppress any

radiation generated by the IC.

5.7.9 PCB Detail 9 –Board GND Plane Design

A PCB ground plane with openings, small compared to the RF wavelength, can be

considered as continuous. Signal lines required for normal operation creating

electrically long slots within the ground plane. A PCB design should accommodate

ground sections on the opposite PCB side to short the slots. This design technique

helps creating a solid antenna ground in spite of the limitations of a cost effective 2-

layer board.

6 Programming

All programming interfaces are available through two 50 mil connectors (EXT0/1).

Using an appropriate base board, the interfaces are available as 100 mil connectors

to directly connect programming tools like JTAGICE mkII.

Base boards with an ISP connector can not be used for ISP with the RCB128RFA1.

The Atmega128RFA1 has the serial programming function mapped to port B. Please

refer to the Atmega128RFA1 data sheet [1] for detailed pin descriptions.