BOOSTXL-PGA460: Cannot Get Energia "GetDistance" to Display Same Distance Values as GUI

Some information from any additional tests I could think to run:

I replaced the muRata MA58MF14-7N values in the .cpp file with the values from the GUI memory map for my unit 0 above. I have noticed that even though the distances reported are still not as consistent as with the GUI, they are still slightly better than before. They don't vary quite as much, and I have fewer "no object..." messages. Here is a copy of the new serial monitor output. As you can see, I chose option 0 for prompt 4 to use those GUI memory map values. Also, I edited the number of values shown for more precision. Nothing else was changed.

I also ran an EDD from GetDistance for P1BL and then P2BL, and compared the curve to one from the GUI. All 3 were almost identical. I forgot to save the two comparison pictures, however, so I won't have those to show unless you ask me to repeat it. In any case, just like the same problem months ago, it seems the problem is with Energia not using my GUI settings somewhere.

Another note. A while back I changed Energia's digitalDelay equation on Akeem's recommendation, in order to make it compensate for pulse count and frequency like the GUI does. I only use 5 pulses and 58.8kHz on my transducers for this application. Here's what it looks like:

double digitalDelay = (5/58800)*343/2;	//For now, assuming 5 pulses and 58.8kHz for every transducer

Thanks in advance!

Hi Akeem,

Once again thank you very much for the continued assistance.

I ran some burst/listen cycles in the GUI using the exact same settings as before. All EEPROM values were kept intact and the both threshold presets are the same as in the Energia code.

I ran the GUI cycle five times and got the following TOF data from the utilities tab:

O1 TOF: 08A2

O1 TOF: 08AA

O1 TOF: 08AA

O1 TOF: 08A4

O1 TOF: 08A5

I then changed the case 0: //Obj1 Distance code in the PGA460_USSC.cpp file to the same as your raw TOF equation above:

case 0: //Obj1 Distance (m)
{
objDist = (ultraMeasResult[1]<<8) + ultraMeasResult[2];
objReturn = objDist; //SKIP TOF TO DISTANCE CONVERSION (objDist/2*0.000001*speedSound) - digitalDelay;
break;
}

Then I run Energia and use the same settings as before, which match perfectly with all values from EEPROM and the threshold map used in the GUI. (I did check that the values stored in EEPROM from Energia were being kept when returning to the GUI, as well).

I made sure Energia was only passing case 0 for this objReturn data, as shown below. The only thing changed from default in this BusDemo sketch is that I am displaying 5 distance digits.

if(successMeas == true){distance = ussc.printUltrasonicMeasResult(0);}
else{distance = 0.00;} //UMR command fail, force print 0.00m

I then get the following distance measurements:

0.32516
0.32516
0.32551
0.32516
0.32516
0.32516
0.32482

If I revert the objReturn equation in the .cpp file back to the original and reupload the code, I get the following distances:

0.32551
0.32551
0.32585
0.32516
0.32516
0.32516
0.32551

Which are almost identical to the ones with the "raw TOF" data above.
Am I messing something up here? Any idea why the raw TOF data matches the converted one?
I'm also not sure why the raw TOF data from the GUI is so different than its reported distances (0x08AA is 2218 in decimal, vs. 0.395m reported distance in GUI).
Is the raw TOF data from the GUI obtained differently than in Energia?

Here's some additional info that may or may not help:
I tested 20 points in a 15x20cm grid and found that the difference between physically-measured and Energia-reported distances (from BusDemo) is somewhat constant over all the points for an individual board, but not across boards, even though both boards are almost exactly the same distance from the test grid (reference photo shown below).

Board 0 (closest in photo) gives a required offset that's between +0.04m and 0.055m depending on the point, and board 1's offset is between +0.018m and 0.035m.

And again, in the GUI both boards give roughly the expected distance values regardless of the point.

I know these boards weren't exactly intended to be used for such a small-scale application, but I'm hoping I can get this working for my current setup.

Ideally I'd be able to get the Energia distances reported to be as accurate as from the GUI without having to do the manual offsets in the sketch for each point, which I am currently doing, so that it could be used outside this exact grid or between points on the grid as well.

If you have any other suggestions that might help with that, I really appreciate it.

Regards,

Joseph Summers

Hi Joseph,

The reason why capturing the raw TOF is important is because this is what the PGA460 reports via UART command 5 "Ultrasonic measurement result". This value is not passed through any equation or conversion in the GUI, so it should match the Energia's output if no register values are changing.

I will need to update the Energia project to include a sketch to output the time-of-flight and/or distance to help with this debug.