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Original question:

PGA450-Q1: PGA450 threshold

PGA450-Q1： PGA450 threshold

pei sun
Prodigy 135 points
Part Number: PGA450-Q1
Other Parts Discussed in Thread: TIDA-00151,

Hi,

I have now received 768 FIFO data in the PGA450.  How to set the threshold length of different step echo?

  • 0
    TI__Mastermind 27950 points

    user5127206,

    The EEPROM stored threshold descriptors can be found in Table 3 register address 0x00 to 0x0A of the PGA450Q1EVM-S User's Guide and TIDA-00151 UART Demo Instructional ( http://www.ti.com/lit/ug/sldu019b/sldu019b.pdf ). Specifically, to change the threshold times, refer to EPPROM register 0x0A, which is described as:
    "Thresholds 1-6 change interval of the level across FIFO for long mode (most significant hex) multiplied by 8 [interval 8 to 120]. Short mode (least significant hex) multiplied by 2 [interval 2 to 15]."
    This means that for an example value of 0x43, the long mode threshold will hold each level by 0x4 * 8 = 32 FIFO samples, and the short mode threshold will hold each level by 0x3 * 2 = 6 FIFO samples.

    To visualize this process, download the PGA450-Q1 threshold mapper tool from the Ultrasonic FAQ page to see how the EEPROM threshold settings impact FIFO object detection. The page to the tool is at the following link:
    e2e.ti.com/.../3607.everything-you-need-to-know-for-ultrasonic-tof-air-coupled-collateral-tools-designs-faq
    as the "PGA450-Q1 Threshold Mapper for EVM-S Example: PGA450-Q1 THRESHOLD CALC for UART OTP EXAMPLE.xlsx":
    e2e.ti.com/.../PGA450_2D00_Q1-THRESHOLD-CALC-for-UART-OTP-EXAMPLE.xlsx
    The column labeled "EEPROM VALUE (Hex)" corresponds to EEPROM addresses 0x00-0A. By changing the value of cell I13, the graph will update to show you how the short and long thresholds change in length (time).

  • 0 in reply to Akeem Whitehead
    Prodigy 135 points

    Hi  Akeem:

    I followed the link and did not find the PGA450 threshold visualization tool.

    According to what you said to change the value of 0X0A in the EEPROM can change the threshold time, then the PGA450 default only this register can change the threshold time? Or other registers can also change the threshold time?

     

     

  • 0 in reply to pei sun
    TI__Mastermind 27950 points

    user5127206,

    I am attaching the PGA450 threshold mapper file directly to this thread if the link is broken for you. I highly recommend you view this file to better understand the threshold mapping based on the EEPROM values.

    8780.PGA450-Q1 THRESHOLD CALC for UART OTP EXAMPLE.xlsx

    Note: this mapper assumes you are using the TIDA-00151 UART & LIN Demo Firmware for PGA450-Q1. With this code example, only EEPROM address 0x0A will change the threshold time. The nibble multiplier values mentioned above are hardcoded in the example firmware (see line pga450_main.c). You can create a custom command to dynamically update the threshold time multiplier.

    Here are the line excerpts from the pga450_main.c file that show the hardcoded multiplier values of 8 (long mode) and 2 (short mode):

    ...

    else if (lcv == ((thrLvlModInterval*8)*(DetectIndex)))

    ...

    else if (lcv == ((thrLvlModInterval*2)*(DetectIndex)))