PGA460: PGA460 Not Detecting Objects with a Different 40kHz Transducer

Hi Taimur,

Thanks for posting to the sensors forum.

Our ultrasonic experts are currently out of office due to the holidays, they will get back to you once they return.

We appreciate your patience.

Best regards,

Jesse

Hello Taimur,

Thanks for your patience as I was out of office. 

Did you ensure you changed the settings for the new transducer? The transducer that comes with the PGA460 is a 58kHz so the settings used there for the driving frequency and filters would differ in comparison.

Do you happen to have the datasheet for the transducer that you are trying to use?

Best,

Isaac

Hello Isaac,

I have updated the FREQUENCY register to match the center frequency of 40 kHz. The calculated value is 0x32. Could you please confirm if this value is correct? I have also tested with other FREQUENCY values, but nothing is captured in the ECHO data dump.  

Below are the characteristics of the transducer we are using:

Please note that we are not using the EVM. We have developed custom hardware with the PGA460, and the transducer is connected via a B78416A2232A003 transformer.

Could you kindly advise how to proceed further and suggest any other methods we can use to test? If possible, could you also provide the optimal register settings for the above-mentioned transducer?

Thanks & Best Regards,
Taimur

Hello Taimur,

The value of 0x32 is correct. I sometimes use a 40kHz transducer but this is in a direct driven mode so you may need to adjust the driver current limit to something higher for a transformer driven application.

Here are the settings.

14 (TVGAIN0),AA
15 (TVGAIN1),AA
16 (TVGAIN2),AA
17 (TVGAIN3),00
18 (TVGAIN4),00
19 (TVGAIN5),00
1A (TVGAIN6),00
1B (INIT_GAIN),40
1C (FREQUENCY),32
1D (DEADTIME),80
1E (PULSE_P1),0A
1F (PULSE_P2),10
20 (CURR_LIM_P1),40
21 (CURR_LIM_P2),40
22 (REC_LENGTH),89
23 (FREQ_DIAG),00
24 (SAT_FDIAG_TH),EE
25 (FVOLT_DEC),7C
26 (DECPL_TEMP),4F
27 (DSP_SCALE),00
28 (TEMP_TRIM),00
29 (P1_GAIN_CTRL),08
2A (P2_GAIN_CTRL),18
2B (EE_CRC),82
40 (EE_CNTRL),00
41 (BPF_A2_MSB),85
42 (BPF_A2_LSB),8D
43 (BPF_A3_MSB),F9
44 (BPF_A3_LSB),A5
45 (BPF_B1_MSB),03
46 (BPF_B1_LSB),2D
47 (LPF_A2_MSB),7E
48 (LPF_A2_LSB),67
49 (LPF_B1_MSB),00
4A (LPF_B1_LSB),CD
4B (TEST_MUX),00
4C (DEV_STAT0),80
4D (DEV_STAT1),00
5F (P1_THR_0),77
60 (P1_THR_1),77
61 (P1_THR_2),77
62 (P1_THR_3),77
63 (P1_THR_4),78
64 (P1_THR_5),88
65 (P1_THR_6),9C
66 (P1_THR_7),D0
67 (P1_THR_8),72
68 (P1_THR_9),10
69 (P1_THR_10),63
6A (P1_THR_11),28
6B (P1_THR_12),30
6C (P1_THR_13),34
6D (P1_THR_14),3C
6E (P1_THR_15),00
6F (P2_THR_0),77
70 (P2_THR_1),77
71 (P2_THR_2),77
72 (P2_THR_3),77
73 (P2_THR_4),78
74 (P2_THR_5),88
75 (P2_THR_6),9C
76 (P2_THR_7),D0
77 (P2_THR_8),72
78 (P2_THR_9),10
79 (P2_THR_10),63
7A (P2_THR_11),28
7B (P2_THR_12),30
7C (P2_THR_13),34
7D (P2_THR_14),3C
7E (P2_THR_15),00
7F (THR_CRC),A5

I wanted to see the transducer in case one end of the transducer was not supposed to be grounded but it looks like it should be the same thing as the Murata 58kHz transducer you were using previously. Can you try swapping the orientation to see if that makes a difference?

It is difficult to provide anything specific on a transducer without having the actual transducer but I hope the register settings I provided are helpful.

Best,

Isaac

Hi Isaac,

I tried with configuration you provided, also by swapping transducer's polarity.

Unfortunately still nothing is captured by PGA460. There is nothing on echo data dump as seen in the plot (Blue).

Any suggestions on how to proceed further?

Best,
Taimur

Hello Taimur,

That is strange, have you tried another transducer perhaps the one you are trying to use may be damaged?

If you tried another one and it seems to still show the same issue, do you happen to have a different 40kHz transducer to test out? Some of our other kits use a PUI Audio UTR-1440K-TT-R which is a 40kHz transducer that we have tested in the past.

Best,

Isaac