Rainbow-electronics ATmega128RFA1 Instrukcja Użytkownika Pobierz pdf (Strona 43)

8266A-MCU Wireless-12/09

ATmega128RFA1

No Symbol

Block Time [µs], (typ) Time [µs], (max)

Comments

24 t

TR24

PLL, TX  RX

32 Maximum PLL settling time TX  RX

25 t

TR25

RSSI, update 2

RSSI update period in receive states, refer to "Reading

RSSI" on page 68

26 t

TR26

ED 140

ED measurement period, refer to "Measurement

Description" on page 69

27 t

TR27

SHR, sync 96

Typical SHR synchronization period, refer to

"Measurement Description" on page 69

28 t

TR28

CCA 140

CCA measurement period, refer to "Configuration and

CCA Request" on page 71

29 t

TR29

Random value

Random value update period, refer to "Random

Number Generator" on page 85

9.4.2 Extended Operating Mode

The Extended Operating Mode is a hardware MAC accelerator and goes beyond the

basic radio transceiver functionality provided by the Basic Operating Mode. It handles

time critical MAC tasks requested by the IEEE 802.15.4 standard or by hardware such

as automatic acknowledgement, automatic CSMA-CA and retransmission. This results

in a more efficient IEEE 802.15.4 software MAC implementation including reduced code

size and may allow operating at lower microcontroller clock rates.

The Extended Operating Mode is designed to support IEEE 802.15.4-2006 compliant

frames; the mode is backward compatible to IEEE 802.15.4-2003 and supports non

IEEE 802.15.4 compliant frames. This mode comprises the following procedures:

Automatic acknowledgement (RX_AACK) divides into the tasks:

• Frame reception and automatic FCS check;

• Configurable addressing fields check;

• Interrupt indicating address match;

• Interrupt indicating frame reception, if it passes address filtering and FCS check;

• Automatic ACK frame transmission (if the received frame passed the address filter

and FCS check and if an ACK is required by the frame type and ACK request);

• Support of slotted acknowledgment using SLPTR bit for frame start.

Automatic CSMA-CA and Retransmission (TX_ARET) divides into the tasks:

• CSMA-CA including automatic CCA retry and random back-off;

• Frame transmission and automatic FCS field generation;

• Reception of ACK frame (if an ACK was requested);

• Automatic frame retry if ACK was expected but not received;

• Interrupt signaling with transaction status.

Automatic FCS check and generation (refer to "Frame Check Sequence (FCS)" on

page 66) is used by the RX_AACK and TX_ARET modes. In RX_AACK mode an

automatic FCS check is always performed for incoming frames.

An ACK received in TX_ARET mode within the time required by IEEE 802.15.4 is

accepted if the FCS is valid and if the sequence number of the ACK matches the

sequence number of the previously transmitted frame. Dependent on the value of the

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 523 524

Komentarze do niniejszej Instrukcji

Brak uwag

Rainbow-electronics ATmega128RFA1 Instrukcja Użytkownika Strona 43

Komentarze do niniejszej Instrukcji

Powiązane produkty i podręczniki dla Czujniki Rainbow-electronics ATmega128RFA1