SI1011-A-GM Silicon Laboratories Inc, SI1011-A-GM Datasheet - Page 289

• Manufacturer Part Number: SI1011-A-GM
• Description: IC TXRX MCU + EZRADIOPRO
• Manufacturer: Silicon Laboratories Inc

Specifications of SI1011-A-GM

• Package / Case: 42-QFN
• Frequency: 240MHz ~ 960MHz
• Data Rate - Maximum: 256kbps
• Modulation Or Protocol: FSK, GFSK, OOK
• Applications: General Purpose
• Power - Output: 20dBm
• Sensitivity: -121dBm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Current - Receiving: 18.5mA
• Current - Transmitting: 85mA
• Data Interface: PCB, Surface Mount
• Memory Size: 8kB Flash, 768B RAM
• Antenna Connector: PCB, Surface Mount
• Number Of Receivers: 1
• Number Of Transmitters: 1
• Wireless Frequency: 240 MHz to 960 MHz
• Interface Type: UART, SMBus, SPI, PCA
• Output Power: 20 dBm
• Operating Supply Voltage: 0.9 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Maximum Supply Current: 4 mA
• Minimum Operating Temperature: - 40 C
• Modulation: FSK, GFSK, OOK
• Protocol Supported: C2, SMBus
• Core: 8051
• Program Memory Type: Flash
• Program Memory Size: 8 KB
• Data Ram Size: 768 B
• Supply Current (max): 4 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1872-5

Add R/W Function/Description
08
taken in setting the drive strength and loading on GPIO2 when the microcontroller clock is used. Excess
loading or inadequate drive may contribute to increased spurious emissions.
Pin 6, ANT may be used as an alternate to control a TR switch. Pin 6 is a hardwired version of GPIO set-
ting 11000, Antenna 2 Switch used for antenna diversity. It can be manually controlled by the antdiv[2:0]
bits in register 08h if antenna diversity is not used. See AN440, register 08h for more details.
23.8.9. Antenna Diversity
To mitigate the problem of frequency-selective fading due to multi-path propagation, some transceiver sys-
tems use a scheme known as antenna diversity. In this scheme, two antennas are used. Each time the
transceiver enters RX mode the receive signal strength from each antenna is evaluated. This evaluation
process takes place during the preamble portion of the packet. The antenna with the strongest received
signal is then used for the remainder of that RX packet. The same antenna will also be used for the next
corresponding TX packet.
This chip fully supports antenna diversity with an integrated antenna diversity control algorithm. The
required signals needed to control an external SPDT RF switch (such as PIN diode or GaAs switch) are
available on the GPIOx pins. The operation of these GPIO signals is programmable to allow for different
antenna diversity architectures and configurations. The antdiv[2:0] bits are found in register 08h “Operating
& Function Control 2.” The GPIO pins are capable of sourcing up to 5 mA of current, so it may be used
directly to forward-bias a PIN diode if desired.
The antenna diversity algorithm will automatically toggle back and forth between the antennas until the
packet starts to arrive. The recommended preamble length for optimal antenna selection is 8 bytes. A spe-
cial antenna diversity algorithm (antdiv[2:0] = 110 or 111) is included that allows for shorter preamble
lengths for beacon mode in TDMA-like systems where the arrival of the packet is synchronous to the
receiver enable. The recommended preamble length to obtain optimal antenna selection for synchronous
mode is 4 bytes.
23.8.10. RSSI and Clear Channel Assessment
Received signal strength indicator (RSSI) is an estimate of the signal strength in the channel to which the
receiver is tuned. The RSSI value can be read from an 8-bit register with 0.5 dB resolution per bit.
Figure 23.25 demonstrates the relationship between input power level and RSSI value. The absolute value
of the RSSI will change slightly depending on the modem settings. The RSSI may be read at anytime, but
antdiv[2:0]
R/W
000
001
010
100
101
011
110
111
Operating & Function
Control 2
Antenna Diversity Algorithm
Antenna Diversity Algorithm
Antenna Diversity Algorithm in Beacon Mode
Antenna Diversity Algorithm in Beacon Mode
GPIO Ant1
0
1
0
1
Table 23.8. Antenna Diversity Control
antdiv[2] antdiv[1] antdiv[0] rxmpk autotx enldm ffclrrx
RX/TX State
D7
D6
GPIO Ant2
Rev. 1.0
1
0
1
0
D5
D4
GPIO Ant1
D3
Si1010/1/2/3/4/5
0
0
1
1
0
1
0
1
Non RX/TX State
D2
D1
GPIO Ant2
ffclrtx
D0
0
0
1
1
0
1
0
1
POR
Def.
00h
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