MSP430FR6047: MCU018

Hi Kumar,

Let me check internally with expert and feedback to you. Thanks.

B.R.

Sal

I also don't have any issues while setting sampling frequency to 8MHz & OSR 10. Issues starts after setting this.

There are no modifications on hardware and software. 

Yes it is programmed with default Demo project.

One thing I want to make clear that this issue occurs only when no ultrasonic sensor is connected to board.  

When ultrasonic sensor is connected to board you do whatever configurations change it will work fine. But when you remove the ultrasonic sensor and if you have configured sampling frequency 8MHz & OSR 10 then issue arises. 

Issues are:-

1) ADC capture stops working.

2) Signal capture stops working.

3) You cannot update the configuration parameters.

You need to flash the firmware again.

Thanks.

Anup Kumar

Hi Hao,

I guess I have found the root cause here. when sampling frequency is 8MHz OSR =10, then 

1.) object->deltaTOF.estimate.numSamplesPerCycle = (int16_t)(params->numSamplesPerCycle * 4096.0f);

In this step number samples = 8 * 4096 = 32768 , but you have type casted this to int16_t so it will be -32768

So when the sensor is connected it works fine because of highlighted part. but when no sensor is connected it will reset.

if(object->absTOF_DNS_results->signalDetected)
{
if(object->windowingMode == USS_windowing_mode_dynamic) {
winStartIndex = 0;
}
else {
// Calculate window start index
if(object->windowingMode == USS_windowing_mode_estimate) {
absTOFFromStartCapture = (int16_t)(((object->absTOF_DNS_results->iq40TotalTOF - object->iq40ADCStartCaptureInstant - object->iq40ADCAdditionalCaptureDelay) << 4) / object->iq44ADCSamplePeriod); //(54us-49us-0)/0.25us=20
winStartIndex = (((int32_t)absTOFFromStartCapture << 12) - ((int32_t)(object->numSamplesPerCycle) * (int32_t)(object->winStartIndexBackOffNumCycles))) >> 12; //20-4*2=12
}
else if(object->windowingMode == USS_windowing_mode_static) {
// USS_Alg_dToF_Window_Type_static
winStartIndex = ((int32_t)(object->numSamplesPerCycle) * (int32_t)(object->winStartIndexBackOffNumCycles)) >> 12;
}
else
{
winStartIndex = 0;
}
if (winStartIndex < 0) {
winStartIndex = 0;
}
}

// Calculate window ramp length
winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles); //4*4
if (winRampLength < 0) {
winRampLength = 0;
}

// Calculate window length and make an even integer
winLength = winRampLength + _Q12rmpy(object->numSamplesPerCycle, object->winNumCycles) + winRampLength; //16+4*28+16=144
// Ensure it does not exceed the total arrayLength taking "winStartIndex" into account
if (winLength > (object->arrayLength - winStartIndex)) {
winLength = object->arrayLength - winStartIndex;
}
winLength = winLength & ~1;
}
else {
// Set default window parameters
winStartIndex = 0;
winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);
winLength = object->arrayLength;
}

I think now it will be more clear to you. please resolve this.

Thanks,

Anup Kumar. 

Emm, interesting point. 

Thanks for pointing that out.

Hi Hao,

I am waiting for solution from your side. I have to further proceed with my development.

Please suggest the solution as soon as possible.

Thanks,

Anup Kumar.

Hi,

Oh, so changing to _IQ12rmpy does not solve the issue?

Best regards,

Cash Hao

Hi Hao,

This issue is solved by making following changes: -

1) object->deltaTOF.estimate.numSamplesPerCycle = (int16_t) (params->numSamplesPerCycle * 4096.0f);  chnging int16_t to int32_t.

2.) Instead of:-   winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);

    It should be:-  winRampLength = _IQ12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);

But i want to ask will you provide the updated USS library version on TI web site along with errata sheet?

Also, who will confirm that the changes I have made has no other impact at all.

Thanks,

Anup Kumar

Hi,

Well, there will not be an update on the USS library. 

And I also tried to change the sampling rate to 8MHz without connecting transducers. I still do not observe any issue from my side. I can still receive message from MCU.

Best regards,

Cash Hao

Hi Hao,

As per the USS library & also as I have shown in my previous reply, it will only work if 

1) object->deltaTOF.estimate.numSamplesPerCycle = (int16_t) (params->numSamplesPerCycle * 4096.0f);  chnging int16_t to int32_t.

2.) Instead of:-   winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);

    It should be:-  winRampLength = _IQ12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);

or under the red highlighted part you include if statement highlighted in yellow part.

if(object->absTOF_DNS_results->signalDetected)
{
if(object->windowingMode == USS_windowing_mode_dynamic) {
winStartIndex = 0;
}
else {
// Calculate window start index
if(object->windowingMode == USS_windowing_mode_estimate) {
absTOFFromStartCapture = (int16_t)(((object->absTOF_DNS_results->iq40TotalTOF - object->iq40ADCStartCaptureInstant - object->iq40ADCAdditionalCaptureDelay) << 4) / object->iq44ADCSamplePeriod); //(54us-49us-0)/0.25us=20
winStartIndex = (((int32_t)absTOFFromStartCapture << 12) - ((int32_t)(object->numSamplesPerCycle) * (int32_t)(object->winStartIndexBackOffNumCycles))) >> 12; //20-4*2=12
}
else if(object->windowingMode == USS_windowing_mode_static) {
// USS_Alg_dToF_Window_Type_static
winStartIndex = ((int32_t)(object->numSamplesPerCycle) * (int32_t)(object->winStartIndexBackOffNumCycles)) >> 12;
}
else
{
winStartIndex = 0;
}
if (winStartIndex < 0) {
winStartIndex = 0;
}
}

// Calculate window ramp length
winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles); //4*4
if (winRampLength < 0) {
winRampLength = 0;
}

// Calculate window length and make an even integer
winLength = winRampLength + _Q12rmpy(object->numSamplesPerCycle, object->winNumCycles) + winRampLength; //16+4*28+16=144
// Ensure it does not exceed the total arrayLength taking "winStartIndex" into account
if (winLength > (object->arrayLength - winStartIndex)) {
winLength = object->arrayLength - winStartIndex;
}
winLength = winLength & ~1;
}
else {
// Set default window parameters
winStartIndex = 0;
winRampLength = _Q12rmpy(object->numSamplesPerCycle, object->winTrapzRampOverNumCycles);
winLength = object->arrayLength;
}

May be in your library code you have changed in that part otherwise it will not work that I am pretty sure.

Thanks

Anup Kumar.

Hi Hao,

First of all, I apologize for the this I will take care of this from now onwards to not to share code online. My last question is: -

What I have reported regarding the 8MHz sampling frequency, is that an issue in code or not?

Thanks 

Anu Kumar.

Hi,

I still do not think that is an issue in the code. Because I could not reproduce your issue on my side with the default project. 

Best regards,

Cash Hao

Hi Hao,

What if in the code if you have typecasted a variable to int16 type & value of that variable is greater than int16 type. Also, this is not an issue.?

And when you use a function whose input variables are int16 type and when you supply int32 type variable to that, is that not an issue?

Thanks,

Anup Kumar.

Hi,

You statement will cause issue. But I do not see the risk in code. numSamplesPerCycle is usually 4 and 4*4096 = 16384 which is inside int16 type. Also the same for winRampLength, there is no way it could be below 0. 

Best regards,

Cash Hao

Hi Hao,

great to hear this from you. Now when  numSamplesPerCycle =8 in case when you have selected the 8 MHz sampling frequency & OSR =10.

then, numSamplesPerCycle is 8 and 8*4096 = 32768. which is violating int16 limit. So, in that case numSamplesPerCycle = -32768.

So, now your winRampLength will be calculated on the basis of numSamplesPerCycle = -32768. which is wrong.

Hope now you got the point.

Thanks,

Anup Kumar

Hi Hao,

Glad to hear this. But I want 8 Mhz sampling frequency. The reason is that at 4 MHz I am observing 25 to 30 ps standard deviation in Delta time of flight.

When I set 8 MHz ampling frequency then this standard deviation in delta time of flight is around 15 ps.

Thanks

Anup Kumar.

Hi,

Setting down to 7.2MHz will still get you a similar result as 8MHz from my view. 

Best regards,

Cash Hao