XENSIV™ BGT60LTR11AIP radar: FAQs – KBA236598

Infineon_Team · ‎Nov 09, 2022

Community Translation: XENSIV™ BGT60LTR11AIP: よくある質問 – KBA236598

Version: *A

1: Can the shield of DEMO BGT60LTR11AIP be used in autonomous mode?

There are two different products with different ordering part numbers (OPN):

SHIELD_AUTONOM_BGT60: BGT60LTR11AIP shield configured in autonomous mode
DEMO BGT60LTR11AIP: BGT60LTR11AIP shield configured through SPI + Radar Baseboard MCU7

DEMO BGT60LTR11AIP is based on a BGT60LTR11AIP shield configured through SPI mode. To convert the shield to autonomous (pulsed) mode instead of SPI mode, you need to make a hardware change (remove the R3 resistor from the QS1 input) as shown in Figure 1.

Figure 1 Converting the shield to autonomous mode

2: What is the data source for the "Motion Tracker" and "Direction Tracker" Radar Fusion GUI display plots for BGT60LTR11AIP?

The "Motion Tracker" and "Direction Tracker" Fusion GUI display plots for BGT60LTR11AIP are the outputs of the MMIC radar internal detector when the “Radar Integrated Motion Sensing” application is selected. On the other hand, when “Advanced Motion Sensing with SPI” is selected, Motion Tracker shows the result of the Advanced Motion Sensing (AMS) algorithm that is running.

Figure 2 Radar Fusion GUI setup

3: How do I vary the sampling rate for BGT60LTR11AIP? Is it limited to 3000 Hz?

The sampling rate depends on the Pulse Repetition Time (PRT) value based on the following formula:

sampling_rate (Hz) = 1 / PRT (s)

BGT60LTR11AIP offers the following PRT values: 250 µs, 500 µs, 1000 µs, and 2000 µs. This means that 4000 Hz is the maximum sampling rate.

4: Why is BGT60LTR11AIP not operated in Continuous Wave mode?

Running BGT60LTR11AIP in Continuous Wave (CW) mode results in the following:

Consumes higher power
Heating of the LDO
Device becomes very sensitive to co-channel interference

Therefore, CW mode can only be used for testing scenarios such as FCC and ETSI certification.

5: How do I reset the DEMO BGT60LTR11AIP board?

Do the following:

Connect the demo board to the PC via USB.
Reset the board by connecting the TP1 erase pin to the 3.3V pin for 3 seconds, as shown in Figure 3. Use a male-to-male connector.
Disconnect the board from the USB port and plug it back.

Figure 3 DEMO BGT60LTR11AIP board

6: How do I activate Adaptive Pulse Repetition Time (APRT) in DEMO BGT60LTR11AIP?

Adaptive Pulse Repetition Time is a power-saving option when the MMIC is used in SPI mode. When enabled (set in Reg2: aprt), it multiplies the PRT by a factor of 2, 4, 8, or 16 (set in Reg13: prt_mult) when no target is detected. When a target is detected, the PRT returns to the default value to ensure reliable detection.

This effectively reduces the ON-time of the MMIC because the default PRT is used only when a target is detected, thereby reducing the overall power consumption. Depending on the use case and the multiplier value selected, power consumption of the shield can be reduced significantly.

Do the following to activate APRT for the DEMO BGT60LTR11AIP device:

Enable APRT by setting aprt (Reg2[14]) bit to "1".
Choose the multiplication factor (2, 4, 8, or 16), by setting prt_mult (Reg13[1:0]) bits to the required values (00, 01, 10, or 11).

You can use the Python wrapper available from the Radar BGT60LTR11AIP IDC package to make these changes using the following APIs:

write_register(self, addr, value)

read_register(self, addr)

The following is an example to activate APRT based on the Python wrapper:

def set_aprt(ltr11, factor):
    val_reg2 = ltr11.read_register(2) & 0xBFFF
    val_reg2 |= (1 << 14)
    ltr11.write_register(2, val_reg2)
    val_reg13 = ltr11.read_register(13)
    val_reg13 = (val_reg13 & 0xFFFC) | factor
    ltr11.write_register(13, val_reg13)

7: What is the maximum range detected after enabling Adaptive PRT?

The following table lists the maximum detection range of a human target of DEMO BGT60LTR11AIP using the default settings (as in Radar Fusion GUI): pulse width (PW) = 5 µs, PRT = 500 µs, hold time = 1 s, threshold = 80, transmitter power = 7, and IF Gain = 50 dB

Table 1 Maximum detection range of a human target for DEMO BGT60LTR11AIP

APRT PRT factor	Maximum detection range (m)
0	6.2
2	6.03
4	6
8	6.1
16	5.7

8: What is the functionality of SPI_RST pin?

When SPI_RST is pulled LOW, the chip is completely reset, similarly as the power-up. As long as SPI_RST=0, no process is being started. Only some constant current (like leakage, therefore assumed to be quite low) is drawn.

When the SPI_RST pin is pulled HIGH, the chip moves to the active state. Whenever SPI_RST rises to ‘1’, processes such as PLL, RF, power amplifier, and baseband are activated similar to the process that starts after a power-on-reset (i.e., when VDD is applied while SPI_RST=1). And the chip always resets. It does not know whether it is the first boot-process or not.

9: What is the ON and OFF time of BGT60LTR11AIP?

For OFF-to-ON time, see Table 2 listing the resulting “First boot-up until first target” which is valid for pulsed mode.

Table 2 First boot-up until the first target

PLL_Trig	SPIDI	SPICLK	dc_rep_rate (Reg7[11:10])	mean_win_len (Reg13[4:2])	phase_win_len (Reg13[7:5])	Resulting “first boot-up until first target”
0	*	*	(1)₁₀=(01)₂: 500 µs	01XOR00=01: 512	01XOR00=01: 512	342 ms
1	0	0	(1)₁₀=(01)₂: 500 µs	01XOR00=01: 512	01XOR00=01: 512	342 ms
1	0	1	(1)₁₀=(11)₂: 2000 µs	11XOR00=11: 128	11XOR00=11: 128	438 ms
1	1	0	(1)₁₀=(00)₂: 250 µs	00XOR00=00: 256	00XOR00=00: 256	134 ms
1	1	1	(1)₁₀=(10)₂: 1000 µs	10XOR00=10: 256	10XOR00=10: 256	374 ms

10: How do I extract I/Q data from BGT60LTR11AIP using Arduino MKR?

The MMIC also supports SPI mode by changing the operation mode with the QS1 pin (see the table below). In this mode, the radar raw data can be extracted from BGT60LTR11AIP for signal processing on a PC or an external MCU using SPI. This sampled radar data can be used for developing customized algorithms.

The shield can also be attached to an Arduino MKR board or an Infineon Radar Baseboard MCU7. Because the shield does not have the pinout to read the I/Q data via shield directly on the MKR board, only the TD and PD pins can be used to get the motion and direction of motion information. Thus, the best way to extract the I/Q data is using the Radar Fusion GUI to record data and parse it later in MATLAB.

Figure 4 QS1 settings

For more information, see AN608 – BGT60LTR11AIP shield.

11: Is it possible to customize the algorithm to detect stationary objects and micro motion in DEMO BGT60LTR11AIP?

BGT60LTR11AIP is based on the Doppler principle which depends on motion. Thus, it is not completely possible to detect the stationary targets, even though it is possible to detect micro motions like breathing at close distance.

References: