LAUNCHXL2-RM57L: HET counter giving lesser value of counts

Apurv Mishra

Part Number: LAUNCHXL2-RM57L
Other Parts Discussed in Thread: RM57L843, HALCOGEN, TMS570LS1224

Hey, everyone!

I am working on a project which uses the Hercules Launchpad RM57Lx. I need to read high-speed pulses from a photon counting module, for which, I am using HET edgeCounter.
Now, for verification, I gave the input to the RM57Lx board as well as an oscilloscope. For 10 microseconds, I am getting 2-3 counts but the oscilloscope gives atleast 50 counts which is correct.

How can I increase my counter resolution? Please suggest. It should be able to count pulses in less than 100 nanoseconds.

Thanks and regards,
Apurv

over 6 years ago

0 Miro over 6 years ago

TI__Mastermind 21425 points

Hello,
Your HET program must be executed in one LRP. If LRP is longer than a period of input signal than pulses will be missed.
In Section 23.2.3 Time Base of device TRM an example is shown how to set HET according to customer needs.

Best regards,
Miro

0 Apurv Mishra over 6 years ago in reply to Miro

Intellectual 750 points

Hey, Miro!

Can we detect and count digital pulses every 75 nanoseconds? I just need to count.
TI Hercules Launchpad RM57Lx is being used, HET is used for counting.

0 Apurv Mishra over 6 years ago

Intellectual 750 points

Part Number: LAUNCHXL2-RM57L

Hey, everyone!

I am using HET counter for counting edges from a photon counting module. I am missing counts.
Can we measure edges of a digital pulse, being generated every 50 nanoseconds?

Thanks and regards,
Apurv

0 Miro over 6 years ago in reply to Apurv Mishra

TI__Mastermind 21425 points

Hello,
For counting edges you can use ECNT instruction. HET IDEs ( http://www.ti.com/tool/HET_IDE ) Algorithm Library provides sample code for edge counting using ECNT:

; Input Edge Counter or Pulse Accumulator using ECNT
; event={ FALL | RISE |BOTH } ---------> Edge Counter
; event={ ACCUHIGH | ACCULOW } -->Pulse Accumulator

L00 ECNT { pin= 1, event= RISE, reg= A, data=0 }
L01 BR { next=L00,cond_addr=L00,event=NOCOND};

This will take 2 cycles.
All N2HET timings are derived from VCLK2 (Section 23.2.3 of device TRM) and the maximum VCLK2 frequency for RM57L843 is 110 MHz (Table 5-2 of device Datasheet). This is about 8.09ns cycle time. For two cycles this is less than 17 ns.

Best regards,
Miro

0 Apurv Mishra over 6 years ago in reply to Miro

Intellectual 750 points

Hi, Miro!

Thank you for your reply. For the clock settings in Project Properties, what does the HET Clock Frequency refer to? 330 MHz or 110 MHz?

Regards,
Apurv

0 Miro over 6 years ago in reply to Apurv Mishra

TI__Mastermind 21425 points

Hello,

According to TRM Section 23.2.3:

All N2HET timings are derived from VCLK2 (see Figure 23-7).

For RM57L843 max VCLK2 is 110MHz.

Best regards,

Miro

0 Apurv Mishra over 6 years ago in reply to Miro

Intellectual 750 points

Hey, one last question, hopefully!

After being done with HET IDE and importing the files generated to HALCoGen, how do we see the output of the ECNT function? I am using CCS.

0 Apurv Mishra over 6 years ago in reply to Miro

Intellectual 750 points

Hey, I assembled the code in HET IDE. In HALCoGen, I enabled and uploaded the .c and .h files in HET tab. How can I get the output of the counter? I am using CCS.

0 Miro over 6 years ago in reply to Apurv Mishra

TI__Mastermind 21425 points

Hello,
Value of the counter is in Data field of ECNT instruction.

Best regards,
Miro

0 Apurv Mishra over 6 years ago in reply to Miro

Intellectual 750 points

Sir, I'm getting all values as 0.
The value in data field here is given 0.
Is it because of that?

Also, what is the minimum period for which RM57Lx can count pulses accurately?
My application gives pulses around 50-100 nanoseconds.

I found the following in the spna225 document:

Please, tell me how do I access the counter value in Code Composer Studio.

Thanks and regards,
Apurv

0 Miro over 6 years ago in reply to Apurv Mishra

TI__Mastermind 21425 points

Hello,

Attached is project for counting edges on N2HET1[1] for TMS570LS1224

4846.HET_FREQ_TMS570LS1224PGE.ZIP

Best regards,

Miro

0 Miro over 6 years ago in reply to Miro

TI__Mastermind 21425 points

Hi,
Please take in account that Automatic Read Clear Feature is enabled ( bit 26 of control field is set). That is why data field is cleared after each read.

Best regards,
Miro

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LAUNCHXL2-RM57L: HET counter giving lesser value of counts