BA45F56xx Wireless Transceiver Application
AN0571EN V1.00
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November 5, 2020
Step 3. Setup the GIO pins: Use the SPI interface to set the GIOxS internal registers. For the setup
values, refer to the datasheet. In most cases, GIO1 will be setup as the TX/RX data output/input,
GIO2 as the interrupt output and GIO3 as the transmit data bit clock. GIO4 will be the received
data bit clock. (GIO1S = 0b010, GIO2S = 0b101, GIO3S = 0b1000, GIO4S = 0b1001).
Step 4. Wake-up the RF: Use the SPI command Light Sleep Command(0x0C) to force the RF to
enter the Light Sleep Mode.
Step 5. Wait for the crystal to stabilise then check whether XCLK_RDY = 1.
Step 6. Setup the Direct Mode: Set DIR_EN to 1.
Step 7. Start the transmit or receive mode: First set RTX_SEL (0: receive, 1: transmit), and start the
frequency synthesiser (SX_EN = 1) and automatic calibration function (ACAL_EN). After
the automatic calibration process has completed (about
300μ
s), then start the transmit and
receive function (RTX_EN = 1).
Step 8. Output/read data: Finally, the GIOx (determined by the setup value) can be used to transmit
or receive data. Here it should be noted that after transmitting or receiving the preamble,
synchronisation characters and trailer, the correct data can be determined according to the
data bit clock, TBCLK/RBCLK. For the TX and RX related timing diagram refer to the
datasheet.
The Direct Mode state switching process is shown in Figure 3. Here the Idle Mode can force the
RF to use the internal low-frequency oscillator which will effectively reduce the wake-up time. The
following modes must be executed in the process sequence of this state switching diagram. For
example, after entering the Idle Mode, it is necessary to return to the Light Sleep Mode, after which
jump to the Standby Mode and then execute the TX or RX program.
