AUREL 650201515G, Руководство пользователя

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RTX-24EM-HP
User guide
The technical characteristics can change without notice. AUR°EL S.p.A doesn’t assume the responsibility to the damages caused by an improper use of the device.
AUR°EL S.p.A. Via Foro dei Tigli, 4 - 47015 Modigliana (FC) – ITALY 12/11/2019 - Rev. A
Tel.: +390546941124 – Fax: +390546941660 Page 24
http://www.aurel.it
9.10 Register TXFIFO and RXFIFO
The EM9209 has two 32 Bytes FIFO’s ( TXFIFO and RXFIFO ). The transmit TXFIFO can be accessed through
the SPI command Write_TXFIFO . The receive RXFIFO can be accessed through the SPI command
Read_RXFIFO .
The transmit
TXFIFO must be loaded prior to transmission. The size of the transmit TXFIFO is monitored at
each write FIFO command or can be viewed at any time through the command Read_TXFIFO_Size .
The receive
RXFIFO can be read after an incoming packet has been received. The size of the receive RXFIFO
is monitored at each Read_FIFO command or can be viewed at any time through the command
Read_RXFIFO_Size
.
Note : Both TXFIFO and RXFIFO are managed by the internal microcontroller, which means that this latter
must be enabled ( Start_Micro ) and running (crystal oscillator enabled, Status[1] = ‘0’). Also, the SPI
command
Reset_Micro
will reset all internal
TXFIFO
and
RXFIFO
pointers to 0.
9.11 Received Signal Strength Indicator (RSSI)
A received signal strength indicator (RSSI) is available through the register
Limit_RSSI[3:0] located in
RAM2@8[3:0] . A RSSI measurement can be activated in two different ways:
Packet RSSI
The communication subroutines defined by SPI command
ROM_Boot with ROM_Boot_Address = 128, 192,
256 and 320 will write the RSSI measured during the packet reception to RAM2 register Limit_RSSI[3:0] .
Payload size (see Section 13) must be greater than 1 byte to get a correct Limit_RSSI[3:0] value.
Channel RSSI
The special subroutine defined by
ROM_Boot with ROM_Boot_Address = 248 will write the measured RSSI
value to RAM2 register Limit_RSSI[3:0] when SPI Aux_com is activated. This allows the user to determine
the amount of RF activity on a given channel. This is useful for determining if there is other RF activity on
the channel (e.g., WiFi).
The relationship between the applied RF power at the antenna (PIN) and the value given by the RSSI
Limit_RSSI[3:0] can be expressed as:
PIN [dBm] = - unsigned (
Limit_RSSI[3:0] ) * 8dB, for -89 dBm < PIN < -48 dBm.
The low limit of RSSI[3:0] is determined by channel thermic noise at typically 2, corresponding to -89 dBm,
while the maximum saturates at 9, at about -48 dBm.
The accuracy of the RSSI is not guaranteed, and is provided for test purposes only.