CC2420-RTR1 datasheet(38/92 Pages) TI

38 / 92 page

CC2420

SWRS041B

Page 38 of 89

There is no hardware support for the data

sequence number, this field must be

inserted and verified by software.

CC2420

includes

hardware

address

recognition, as described in the Address

Recognition section on page 41.

Bits: 0-2

7-9

10-11

12-13

14-15

Frame

Type

Security

Enabled

Frame

Pending

Acknowledge

request

Intra

PAN

Reserved

Destination

addressing

mode

Reserved

Source

addressing

mode

Figure 19. Format of the Frame Control Field (FCF) [1]

16.4

Frame check sequence

A 2-byte frame check sequence (FCS)

follows the last MAC payload byte as

shown in Figure 17. The FCS is calculated

over the MPDU, i.e. the length field is not

part of the FCS. This field is automatically

generated and verified by hardware when

the MODEMCTRL0.AUTOCRC control bit is

set. It is recommended to always have this

enabled,

except

possibly

for

debug

purposes. If cleared, CRC generation and

verification

must

performed

software.

The FCS polynomial is [1]:

16 + x12 + x5 + 1

The

CC2420 hardware implementation is

shown in Figure 20. Please refer to [1] for

further details.

In transmit mode the FCS is appended at

the correct position defined by the length

field. The FCS is not written to the

TXFIFO, but stored in a separate 16-bit

In receive mode the FCS is verified by

hardware. The user is normally only

interested in the correctness of the FCS,

not the FCS sequence itself. The FCS

sequence itself is therefore not written to

the RXFIFO during receive.

Instead, when MODEMCTRL0.AUTOCRC is

set the two FCS bytes are replaced by the

RSSI value, average correlation value

(used for LQI) and CRC OK/not OK. This

is illustrated in Figure 21.

The first FCS byte is replaced by the 8-bit

RSSI value. This RSSI value is measured

over the first 8 symbols following the SFD.

See the RSSI section on page 48 for

details.

The 7 least significant bits in the last FCS

byte

are

replaced

the

average

correlation value of the 8 first symbols of

the received PHY header (length field) and

PHY Service Data Unit (PSDU). This

correlation value may be used as a basis

for calculating the LQI. See the Link

Quality Indication section on page 49 for

details.

The most significant bit in the last byte of

each frame is set high if the CRC of the

received

frame

correct

and

low

otherwise.

r10

r11

r12

r13

r14

r15

Data

input

(LSB

first)

Figure 20.

CC2420 Frame Check Sequence (FCS) hardware implementation [1]

CC2420-RTR1 数据表(PDF) 38 Page - Texas Instruments

CC2420-RTR1 数据表(HTML) 38 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92

数据表下载