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Run Bluetooth Single-Item RF Tests

Single-item testing is the SDK's low-level RF path for board tuning, FCC/CE pre-compliance, and investigating one carrier or modulation setting at a time. It is not a product feature and does not replace BQB signaling tests.

Prepare the DUT and tool

Prepare a DUT, PC, USB data cable (not charge-only), RF coax, and a communications tester or spectrum analyzer. Expose VBAT, GND, and UART1 TX/RX for modulated BLE/BT tests. For a single-carrier (CW) test on SF32LB55x, also expose UART3 TX/RX. The default mappings are:

Table: Default UART mappings for modulated and single-carrier tests

Device/package UART1 TX/RX for modulated tests Single-carrier (CW) control UART
SF32LB52x PA19 / PA18 UART1
SF32LB551 PA49 / PA51 UART3 (PB45 / PB46)
SF32LB555 / SF32LB557 PA17 / PA19 UART3 (PB45 / PB46)
SF32LB56xU (QFN) PA17 / PA18 UART1
SF32LB56xV (BGA) PA34 / PA30 UART1
SF32LB57x PA19 / PA18 UART1
SF32LB58x PA32 / PA31 UART1

SF32LB55x UART1 pins vary by part number. For modulated BLE/BT tests, connect UART1 to the PC at 1,000,000 baud. For SF32LB55x single-carrier tests, use UART3 (PB45/PB46) instead; the other listed families use UART1. Apply the target project's pin configuration if it differs from these defaults. Connect the RF port to the instrument through coax, account for cable loss, and distinguish conducted from radiated measurements.

Family scope

The UART table is the consolidated family/package comparison. The topology and SiFli_RfTool screenshots that follow are SF32LB52x source examples; select the actual chip family in the tool and verify the target project's UART mapping.

Conflicting SF32LB58x UART mapping in official guides

The Bluetooth Individual RF Test Guide lists UART1 TX/RX as PA32/PA31, while the general RF Test Guide lists the RF-debug UART as PA31/PA32. Confirm the target firmware's test path and board pinmux before wiring; do not assume these conflicting guide-specific mappings are interchangeable.

Bluetooth single-item test topology

Figure: SF32LB52x source example — the PC controls the DUT through UART/HCI while the RF port connects to a tester or spectrum analyzer through coax.

Enter RF test mode

  1. Boot the DUT and keep it awake.
  2. Send the FinSH command bt_cm uart_dut through SiFli_Trace.
  3. Verify the hexadecimal response 04 0E 04 XX 03 0C 00.
  4. Disconnect the terminal; SiFli_RfTool will use the same UART for HCI control.

Transmit a BLE or Classic BT signal

  1. Open SiFli_RfTool.exe, select the chip family, choose BLE non-signaling or BT non-signaling, select the UART1 COM port, and connect at 1,000,000 baud.
  2. For BLE, set Frequency, Data Length, payload, and PHY, then select Start TX. Stop TX before changing a channel or PHY.
  3. For Classic BT, set Frequency, Data Length, and Packet Type, then select Start TX. Stop TX before changing packet parameters.
  4. On the tester, match the channel, packet type, payload, and PHY. A spectrum analyzer can show the waveform when no communications tester is available.

The SDK source includes LB52x HDK reference TX levels, but those values are board-specific. Use them only as a debugging reference and measure the actual product board.

SiFli_RfTool main controls

Figure: SF32LB52x source example — the tool's chip-family, mode, UART, baud-rate, and TX/RX controls; verify these selections before applying a test vector.

SiFli_RfTool BLE TX settings

Figure: SF32LB52x source example — select the chip, mode, channel, payload, PHY, data length, and power before starting TX.

Receive and calculate sensitivity

Stop TX before entering RX. Set the channel and press Start RX; stop RX before changing it. For BLE RX, configure the tester for Direct Test Mode, select the PHY/channel, send 1,500 packets, and calculate:

PER = (1500 - received_packets) / 1500 × 100%

Record RSSI as well. For Classic BT RX, use a CMW500 GPRF Generator waveform such as DH1/2-DH1/3-DH1 and record received packets, error packets, bit counts, BER, and RSSI. The BLE and Classic BT RF paths share hardware; do not run them in parallel.

SiFli_RfTool BLE RX settings

Figure: SF32LB52x source example — stop TX before RX and record the channel, modulation, PHY, and receive result.

Single-carrier and instrument setup

Stop the current operation before switching to a single-carrier (CW) test. On SF32LB55x, move the DUT-to-PC connection from UART1 to UART3 (PB45/PB46), select that port's COM port in SiFli_RfTool, and use 1,000,000 baud. Use UART1 for the other listed families. Set the carrier frequency and TX power, start transmission, and inspect the output on a spectrum analyzer or power meter.

For modulated BLE/BT TX measurements with a tester, select StandAlone (Non Signaling) reception and match the channel, packet type, payload, and PHY configured in SiFli_RfTool. For DUT RX measurements, configure the tester as the signal source: BLE uses DTM parameters, while Classic BT uses a GPRF waveform.

If the tool or serial connection becomes unresponsive, close SiFli_RfTool, power-cycle the DUT, wait for boot, and reconnect. Keep the tool version, firmware identity, chip/package, UART pins, board revision, channel, PHY/packet type, power, cable loss, instrument configuration, and raw results with the test record.

Tester non-signaling receive configuration

Figure: SF32LB52x source example — select StandAlone (Non Signaling) and match the DUT channel and packet parameters.

Official family sources: SF32LB52x, SF32LB55x, SF32LB56x, and SF32LB58x.

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