si4420 Silicon Laboratories, si4420 Datasheet - Page 22

• Manufacturer Part Number: si4420
• Description: Si4420 Universal Ism Band Fsk Transceiver
• Manufacturer: Silicon Laboratories

15. Status Read Command
The read command starts with a zero, whereas all other control commands start with a one. If a read command is identified, the status bits
will be clocked out on the SDO pin as follows:
Status Register Read Sequence with FIFO Read Example:
RGIT
FFIT
POR
RGUR
FFOV
WKUP
EXT
LBD
FFEM
ATS
RSSI
DQD
CRL
ATGL
OFFS(6)
OFFS(3) -OFFS(0)
TX register is ready to receive the next byte (Can be cleared by Transmitter Register Write Command)
The number of data bits in the RX FIFO has reached the pre-programmed limit (Can be cleared by any of the
FIFO read methods)
Power-on reset (Cleared after Status Read Command)
TX register under run, register over write (Cleared after Status Read Command)
RX FIFO overflow (Cleared after Status Read Command)
Wake-up timer overflow (Cleared after Status Read Command)
Logic level on interrupt pin (pin 16) changed to low (Cleared after Status Read Command)
Low battery detect, the power supply voltage is below the pre-programmed limit
FIFO is empty
Antenna tuning circuit detected strong enough RF signal
The strength of the incoming signal is above the pre-programmed limit
Data quality detector output
Clock recovery locked
Toggling in each AFC cycle
MSB of the measured frequency offset (sign of the offset value)
Offset value to be added to the value of the frequency control parameter (Four LSB bits)
Si4420
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