2 high data rate modes, 1 overview, 2 high data rate packet structure – Rainbow Electronics ATmega128RFA1 User Manual
Page 86: High data rate modes" on, Atmega128rfa1
86
8266A-MCU Wireless-12/09
ATmega128RFA1
•
Generate random values for AES key generation (see
);
The random number is updated every t
TR29
= 1 µs in Basic Operation Mode receive
states. The values are stored in bits RND_VALUE of register PHY_RSSI.
9.8.2 High Data Rate Modes
The main features of the High Data Rate Modes are:
•
High Data Rate Communication up to 2 Mb/s;
•
Support of Basic and Extended Operating Mode;
•
Support of other features of the Extended Feature Set;
9.8.2.1 Overview
The radio transceiver also supports alternative data rates higher than 250 kb/s for
applications beyond IEEE 802.15.4 compliant networks.
The selection of a data rate does not affect the remaining functionality. Thus it is
possible to run all features and operating modes of the radio transceiver in various
combinations.
The data rate can be selected by writing bits OQPSK_DATA_RATE of register
TRX_CTRL_2.
The High Data Rate Modes occupy the same RF channel bandwidth as the
IEEE 802.15.4 – 2.4 GHz 250 kb/s standard mode. The sensitivity of the receiver is
reduced due to the decreased spreading factor. The following table shows typical
values of the sensitivity for different data rates.
Table 9-23. High Data Rate Sensitivity
High Data Rate
Sensitivity
Comment
250 kb/s
-100 dBm
PER ≤ 1%, PSDU length of 20 octets
500 kb/s
-9 dBm
PER ≤ 1%, PSDU length of 20 octets
1000 kb/s
-9 dBm
PER ≤ 1%, PSDU length of 20 octets
2000 kb/s
-8 dBm
PER ≤ 1%, PSDU length of 20 octets
By default there is no header based signaling of the data rate within a transmitted
frame. Thus nodes using a data rate other than the default IEEE 802.15.4 data rate of
250 kb/s are to be consistently configured in advance. The configurable start of frame
delimiter (SFD) could be alternatively used as an indicator of the PHY data rate (see
"Configurable Start-Of-Frame Delimiter (SFD)" on page 91
).
9.8.2.2 High Data Rate Packet Structure
Higher data rate modulation is restricted to only the payload octets in order to allow
appropriate frame synchronization. The SHR and the PHR field are transmitted with the
IEEE 802.15.4 compliant data rate of 250 kb/s (refer to
"Introduction – IEEE 802.15.4-
).
A comparison of the general packet structure for different data rates with an example
PSDU length of 80 octets is shown in