AT86RF211 Datasheet, PDF (28/48 Pages) ATMEL Corporation – FSK Transceiver for ISM Radio Applications

Table 6. CTRL1 Detailed Description^(1)(2)(4)(3) (Continued)
Name
Number
of Bits Comments
–
1
reserved, must be kept to reset value: 0
RXFS
XTALFQ
2
RX frequency selection
(00)₂: F0
(01)₂: F1
(10)₂: F2
(11)₂: F3
1
Crystal frequency
0: 10.245 MHz (when IF1 = 10.7 MHz)
1: 20.945 MHz (when IF1 = 21.4 MHz)
reset value: (10)₂
reset value: 0
FSKBW
1
Discriminator range
0: Narrow Discriminator BW
1: Standard Discriminator BW
reset value: 1
FSKPOL
1
Polarity of DATAMSG
0: inverted signal
1: direct signal
reset value: 1
DSREF
1
Data Slicer reference voltage
0: external reference: SKFILT pin voltage
1: internal reference: DAC level voltage
reset value: 1
–
1
reserved, must be kept to reset value: 0
–
1
reserved, must be kept to reset value: 0
MOFFSET
1
0: internal ADC sets to V_CC measurement
1: internal ADC sets to DISCOUT DC level measurement
reset value: 0
–
1
reserved, must be kept to reset value: 0
Notes:
1. The same ADC is used to measure RSSI or V_CC voltage. When the V_CC voltage is measured, the RSSI measurement is
stopped (previously measured RSSI is kept into STATUS Register). This can disturb the reception process (if a threshold is
used for DATAMSG validation). So, it is not recommended to measure V_CC in reception mode.
2. V_CC measurement can not be done when the AT86RF211 is in power-down mode.
3. While in V_CC measurement, it is possible to measure the DC output of the discriminator.
4. Description of RSSI measurement with hysteresis mechanism: if the RSSI measurement is higher than the high RSSI level,
DATAMSG is validated (high RSSI level = TRSSI + HRSSI). If the RSSI measure is lower than the low RSSI level, DATA-
MSG is inhibited (low RSSI level = TRSSI - HRSSI). Between these two levels, DATAMSG validation depends on the
previous measurement.
Example:
TRSSI = 32 and HRSSI = 4 implies High RSSI level = 26 and Low RSSI level = 28
MRSSI sequence
RSSI level
DATAMSG
27
NOK
32
NOK
35
NOK
36
OK
valid
35
OK
valid
32
OK
valid
29
OK
valid
28
OK
valid
27
NOK
25
NOK
28 AT86RF211
1942C–WIRE–06/02