PGA450-Q1

Saurabh,

If you have the PGA450EVM, you don't need to program the PGA450 to use the evaluation tab.  You just need the right settings.  The attached picture shows settings you can start with for a 40kHz transducer.

You can write to registers using SPI to configure and start a distance measurement; however, you'll need to program an algorithm into the 8051uC inside the PGA450 to detect where an object is located.  Before worrying about that, you can observe what the echo signal looks like by reading and plotting the FIFO RAM.  That's what the "eval monitor" tab in the GUI does, but you can also export the data to excel and look at it that way.

-Clancy

Saurabh,

Here is the modified firmware for 40kHz.  Here is a list of changes from the standard firmware:

In the PGA450_int.c file:

BPF_A2_MSB = 0xF4

BPF_A2_LSB = 0xE6 // this A2 coefficient correspond to a center frequency of 40kHz for the bandpass filter.  The appropriate value can be looked up in the datasheet for other frequencies.

In the PGA450_isrs.c file:

BURST_ONA_MSB = 0x00;

BURST_ONA_LSB = 0xC8;   // This controls the frequency of the driving signal for the ultrasonic burst.  To calculate the appropriate number use this equation:   ON/OFF_coefficient = Convert2Hex( 16MHz/40kHz/2 )

BURST_OFFA_MSB = 0x00;

BURST_OFFA_LSB = 0xC8;

Saurabh,

You won't be able to use the GUI without the PGA450EVM.  Have you ordered one yet?

The PGA450 must be in reset to communicate via SPI.  While in reset, the PGA450 will not execute code in its OTP or DEVRAM memory spaces.  You can program the ESFRs over SPI with the desired settings to send and receive an ultrasonic burst.

When the micro inside the PGA450 is not in reset, the programmed code in the OTP/DEVRAM can execute.  You can use this to write to the ESFRs as well. (as you can see in the example firmware)

-Clancy