4.9 HAL_EnableRFCtrl

Definition: This function is called by the stack to inform HAL which RF path signal is used for TX/RX and, based on the RF front-end design, which respective GPIO pin will be controlled.

Usage of the RFCTRL1 variable:

The RFCtrl1 parameter is used to select the RF output frequency range (or band). The following values are applicable for the parameter.

RFO_LF is used when the RF output frequency range is lesser than 525 MHz (band 2/3).
RFO_HF is used when the RF output frequency range is greater than 779 MHz (band 1).
PA_BOOST is used regardless of the RF output frequency. But, when the TX power is greater than +15 dBm.
When the TX power is between -4 dBm to +15 dBm, either RFO_LF or RFO_HF should be used. The following table describes the frequency range and TX power of RFCtrl1.

Note: For more details on the frequency limits and required bands, refer to the SX1276 data sheet.

Table 4-2. RFCtrl1 Frequency Range and Power
ENUM Value	Frequency Region	TX Power
RFO_LF	< 525 MHz	-4 to +15 dBm
RFO_HF	From 779 MHz	-4 to +15 dBm
PA_BOOST	All frequencies	+2 to +17 dBm

All 3 ENUM values represent a pin out from the SX1276 transceiver.
The RFCtrl1 value indicates which of these 3 pin-outs the signal will be received at. For example, if the frequency is 868MHz and the output power is +10dBm, then the signal will come from the RFO_HF pin.
Refer to the SX1276 data sheet, RF power amplifiers section for more details on the transceiver operation with different frequencies and output power.
Refer to the SAM R34 data sheet for the pin mapping details for these 3 pins.

Usage of RFCTRL2 variable:

The RFCtrl2 parameter is used to select either a transmit or receive operation by the transceiver.

For a receive operation, front-end RF circuitry routes the received signal through either the RFI_LF or RFI_HF pin.
Based on the frequency range, either RFI_LF or RFI_HF is selected.
The frequency range can be determined from the RFCtrl1 parameter to select between RFI_LF and RFI_HF.

Table 4-3. Master Truth Table for RFCtrl1 and RFCtrl2
RFCtrl1	RFCtrl2	Operation
RFO_LF	TX	Transmit operation Transmit Frequency – < 525 MHz Output power – -4 to +15 dBM
RFO_HF	TX	Transmit operation Transmit Frequency – >779 MHz Output power – -4 to +15 dBM
PA_BOOST	Do not care	Transmit operation Transmit Frequency – All Output power – >15 dBm
RFO_LF	RX	Receive Operation Receive Frequency – < 525 MHz
RFO_HF	RX	Receive Operation Receive Frequency – > 779 MHz

For the SAM R34 Xplained Pro board or WLR089 Xplained Pro board:

Only RFO_HF and PA_BOOST values of RFCtrl1 are valid and used to set the BAND_SELECT pin. Refer to the SAM R34 Xplained Pro board or WLR089 Xplained Pro board for more details on the front-end RF circuit design.
RFO_LF is not used because neither the SAM R34 Xplained Pro nor WLR089 Xplained Pro supports the frequency operation in < 525 MHz.
The RFCtrl2 input is not used. The SAM R34 Xplained Pro or WLR089 Xplained Pro front-end RF circuit does not need to control based on the TX and RX operation.

Syntax

void HAL_EnableRFCtrl(RFCtrl1_t RFCtrl1, RFCtrl2_t RFCtrl2)

Table 4-4. **Input Parameters**
Parameters Name	Parameter Type	Description
RFCtrl1	ENUM	RF Control 1 indicates the FREQUENCY band (Higher UHF or Lower UHF) or PA Boost enabled. RFO_LF = 0 RFO_HF = 1 PA_BOOST = 2
RFCtrl2	ENUM	RF Control 2 indicates the Transmit or Receive path. RX = 0 TX = 1

Return Types and Values

<void>

API Type – Synchronous