CC2430-RTR1-F64Z datasheet(175/234 Pages) TI

175 / 234 page

CC2430

CC2430 PRELIMINARY Data Sheet (rev. 1.03) SWRS036A

Page 175 of 232

14.15 MAC protocol data unit

The FCF, data sequence number and

address information follows the length field

as shown in Figure 45. Together with the

MAC data payload and Frame Check

Sequence, they form the MAC Protocol

Data Unit (MPDU).

The format of the FCF is shown in Figure

47. Please refer to [1] for details.

There is no hardware support for the data

sequence number, this field must be

inserted and verified by software.

CC2430

includes

hardware

address

recognition, as described in the Address

Recognition section on page 177.

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 47: Format of the Frame Control Field (FCF) [1]

14.16 Frame check sequence

A 2-byte frame check sequence (FCS)

follows the last MAC payload byte as

shown in Figure 45. 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 RF register MDMCTRL0L.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 be

performed by software.

The FCS polynomial is [1]:

16 + x12 + x5 + 1

The

CC2430 hardware implementation is

shown in Figure 48. 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 MDMCTRL0L.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 49.

The first FCS byte is replaced by the 8-bit

RSSI value. See the RSSI section on page

181 for details.

The seven least significant bits in the last

FCS byte are replaced by 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 182 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.

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