MRF24XA_15 Datasheet, PDF (105/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
REGISTER 4-4: BBCON (BASEBAND CONFIGURATION REGISTER)
ADDRESS 0x38
R/W-0
R/W-0
R/W-11
R/W-0
R/W-001
RNDMOD AFCOVR RXGAIN<1:0> PRMBHOLD
PRMBSZ<2:0>
bit 7
bit 0
Legend: W = Writable bit
-n = Value at POR
r = Reserved
R = Readable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
bit 6
bit 5-4
bit 3
bit 2-0
RNDMOD: Random Modulation bit
If this bit is set, the transmitter randomly transmits DSSS symbols or MSK chips if PRMBHOLD bit is
set. The purpose of this register is only for testing.
AFCOVR: AFC Override bit
If this bit is set, the receiver uses CFOMEAS register as the CFO in reception.
RXGAIN<1:0>: Receiver Gain Register Field bits
If this bit is set, the AGC operation is inhibited in the receiver and the receiver radio gain Configuration
is selected between three different gain levels. Encoding:
11 = AGC operation is enabled (default value)
10 = High gain
01 = Middle gain
00 = Low gain
This feature is used for test and streaming purposes. To reduce the required interframe-gap, the RXGAIN
must set to one of the fixed gain options when the MAC is in Streaming mode.
PRMBHOLD: Preamble Hold Enable bit
Effect: Appends extra bytes to the transmitted preamble in endless repetition until it is cleared.
Details: The hardware checks this bit during transmission before finishing the preamble. The DR<2:0>
and the register OPTIMAL determine the appropriate preamble byte and applies the modulation format.
When this flag is released the transmission of the current preamble byte is completed followed by trans-
mitting the LENGTH field and the payload.
1 = Enable endless preamble repetition
0 = Disable/stop endless preamble repetition
PRMBSZ<2:0>: Preamble Size Adjustment Field bits
Enables adjusting the transmitted preamble length when OPTIMAL = 1. Encoding:
500 kbps preamble length = (PRMBSZ<2> + 4) units, where unit = 16 μs (1 octet at 500 kbps)
1 Mbps preamble length = (PRMBSZ<1:0> + 8) units, where unit = 4 μs (1 octet at 2 Mbps)
2 Mbps preamble length = (PRMBSZ<1:0> + 8) units, where unit = 4 μs (1 octet at 2 Mbps)
This register field does not affect the Legacy frames and 125/250 kbps optimized frames.
 2015 Microchip Technology Inc.
Preliminary
DS70005023C-page 105