GMSK Packet Data Modem and RF Transceiver
CMX990
5.2.6 Read Only Registers
Data Buffer
$00
Read
7
6
5
4
4
3
2
1
0
0
Bit:
Rx Data
Status1
$01
Read
7
6
5
3
2
1
Bit:
Packet
Detect
IRQ
BFREE
IBEMPTY
DIBOVF
CRCFEC
DQRDY
MoBaN
Data Quality Register $02
Read
7
6
5
4
3
2
1
0
Bit:
Data Quality Reading (0-255)
Status2
$03
Read
7
6
5
4
3
2
1
0
Bit:
SPC
Aux ADC
PLL Lock
lost
Main PLL
in lock
Aux PLL
in lock
Tx PLL
in lock
Freq offset
error
IQ offset
complete
command conversion
complete
complete
Frequency Offset
$04
Read
7
6
5
4
3
2
1
0
Bit:
Rx measured RF frequency offset (-64 to 63)
Good Data
The 2's complement number read from bits 7 to 1 represents the estimate of the frequency error between
the transmitter and receiver carriers and is equivalent to 16Hz per bit, this value is only valid if bit 0 = '1'.
If bit 0 = '0' the RF frequency offset will not be computed and bits 7 to 1 will hold the last value
calculated.
Signal Strength
$05
Read
7
6
5
4
3
2
1
0
Bit:
Rx measured signal strength RSSI (0-255)
The value read from this register represents the latest estimate of the RSSI as the number of dB above a
level of -150 dB (to be confirmed).
Aux ADC 0
Bit:
$08-09 Read
7
6
6
6
5
5
5
4
3
2
2
2
1
1
1
0
0
0
7
6
5
4
3
2
1
1
1
0
0
0
MSB
X
X
X
X
X
X
LSB
LSB
LSB
Aux ADC 1
Bit:
$0A-0B Read
7
4
3
7
6
5
4
3
2
MSB
X
X
X
X
X
X
Aux ADC 2
Bit:
$0C-0DRead
7
4
3
7
6
5
4
3
2
MSB
X
X
X
X
X
X
ã 2004 CML Microsystems Plc
52
D/990/1
CMLMICRO [ CML MICROCIRCUITS ]
