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Original question:

PGA450-Q1: PGA450-Q1 about the SPI and the distance measuring questions

PGA450-Q1: pga450-q1evm-s: about the SPI and the distance measuring

Ganjikunta Kumar
Prodigy 30 points
Part Number: PGA450-Q1
Other Parts Discussed in Thread: PGA450Q1EVM, , TIDA-00151, PGA460-Q1

I am using the PGA450-Q1EVM-S at a supply voltage of 8V. I am not using PGA450Q1EVM board for evaluation. I am connecting external microcontroller to configure the module.

I would like to use SPI interface to communicate for the distance measuring. But I do not know how to use SPI to read the receive signal for the distance measuring.

I came to know that the micro is to be in the RESET state, then the EN_CTRL's BURST_A_EN bit must be toggled from 0 --> 1. After this the FIFO start to fill.

What are the commands to excite the transducer (EN_CTRL's BURST_A_EN) and to configure the ultrasonic transmission by using SPI?

What are the commands for short distance and long distance measurement by using SPI communication?

To calculate distance, What are the blanking time and downsample values for PGA450-Q1EVM-S as it is already programmed?

  • 0
    TI__Genius 11015 points
    Ganjikunta,

    We have received your question & I we will respond in a couple of days.
  • 0
    TI__Mastermind 27920 points
    Ganjikunta,

    Unfortunately, we have not created any SPI based example code to control the PGA450-Q1.
    You will need to refer to section 7.5.1 "SPI Interface" of the PGA450-Q1 for details on using the SPI Protocol. Specifically, Table 15. "SPI Protocol Transfer Widths" outlines the available commands to read/write to specific memory banks of the PGA450-Q1 registers through SPI.

    You are correct about toggling the EN_CTRL's BURST_A_EN bit to trigger the driver and receiver activity to fill the FIFO.

    You can see the default configuration of the EVM-S's blanking time and downsample values in the PGA450_init.c file of the "TIDA-00151 UART & LIN Demo Firmware for PGA450-Q1" ( www.ti.com/.../tidcab3 ):

    #define DOWNSAMPLE_50
    #ifdef DOWNSAMPLE_50 // LPF CF = 4KHz, 50 downsamples
    DOWNSAMPLE = 0x32; // 50us output rate
    LPF_B1_MSB = 0x35;
    LPF_B1_LSB = 0xDD;
    LPF_A2_MSB = 0x14;
    LPF_A2_LSB = 0x46;
    #endif

    Blanking time is dependent on whether you use the short, long, or custom burst mode. Review the code and see the "PGA450Q1EVM-S User's Guide and TIDA-00151 UART Demo Instructional" ( www.ti.com/.../sldu019 )to understand the differences between these burst modes.

    You can use the newer PGA460-Q1 in SPI mode, which we have example code for. Is there a reason you are using the older PGA450-Q1? We will soon be releasing a small form factor PGA460-Q1 if hardware is a concern.