Rf22 – Rainbow Electronics RF22 User Manual

Page 70

RF22

Version: 0.1 Date: 12/23/2008

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Register 33h. Header Control 2

Bit

Name

Reserved

hdlen[2:0]

fixpklen

synclen[1:0]

prealen[8]

Type

R/W

Reset value = 00100010

Bit

Name

Function

Reserved

Reserved.

6:4

hdlen[2:0]

Transmit/Receive Header Length.
Length of header used if packet handler is enabled for TX/RX (enpactx/rx). Headers are
transmitted/received in descending order.
000: No TX/RX header
001: Header 3
010: Header 3 and 2
011: Header 3 and 2 and 1
100: Header 3 and 2 and 1 and 0

fixpklen

Fix Transmit/Receive Packet Length.
When fixpklen = 1 the packet length (pklen[7:0]) is not included in the header. When fixpklen = 0
the packet length is included in the header.

2:1

synclen[1:0]

Synchronization Word Length.
The value in this register corresponds to the number of bytes used in the Synchronization Word.
The synchronization word bytes are transmitted in descending order.
00: Synchronization Word 3
01: Synchronization Word 3 and 2
10: Synchronization Word 3 and 2 and 1
11: Synchronization Word 3 and 2 and 1 and 0

prealen[8]

MSB of Preamble Length.
See register Preamble Length.

Register 34h. Preamble Length

Bit

Name

prealen[7:0]

Type R/W

Reset value = 00001000

Bit

Name

Function

7:0

prealen[7:0]

Preamble Length.
The value in the prealen[8:0] register corresponds to the number of nibbles (4 bits) in the packet.
For example prealen[8:0] = ‘000001000’ corresponds to a preamble length of 32 bits (8*4bits) or 4
bytes. The maximum preamble length is prealen[8:0] = 111111111 which corresponds to a 255
bytes Preamble. Writing 0 will have the same result as if writing 1, which will send one single
nibble of preamble.

Register 35h. Preamble Detection Control 1

Bit

Name

preath[4:0]

SPARE

Type

R/W

Reset value = 00100000

Bit

Name

Function

7:3

preath[4:0]

Number of nibbles processed during detection.

2:0

SPARE

SPARE bits.