NHET based time interval generation

Hello Vitalji,

For #1, you use RTI to generate this periodic interrupt.  In my opinion, NHET is an overkill for this task.  The RTI module is designed specifically for this purpose.  Just setup only one time and all the counter and comparator will be automatically updated for 10 ms.  As a matter of fact, you can generate multiple periodic interrupts.  We can provide example RTI codes for you.

For #2, i do not really understand your description.  Can you please clarify in term of an example on how you would envision the two timers (one is NHET and other timer is in another device) and the software running on TMS570 R4 would interact?

Thanks and Best Regards,

Henry Nguyen

Hi Vitalij,

Thanks for the clarification.  I am clear now on what you want to do.

For #1 and #2, you can use RTI to handle this task.

Use block 0 counters for #1 solution and block 1 counters for #2 solution.

Please download HalCoGen (GUI interface to generate baseline drivers and start up codes) from http://www.ti.com/tool/halcogen.

Create new project (select correct device).

Go to DriverEnable tab (see attached screen shot) and select only RTI driver to be generated.

Go to RTI tab (see attached screen shot) and configure interrupt interval time for 1 ms and 10 ms.

Click on generate codes.  This will be baseline codes.  You can add user configuration on top of these baseline API.

One caveat  for using RTI for solution #2 is that user has to write to disable block 1 counters to stop the counter before servicing the 1 ms interrupt.  The RTI does not have the one shot option.

If writing to disable RTI block 1 counters is not an option, then you can also write a simple NHET program to do this.

Example as below:

; count up to X ms and stop.
; user has to write 1 to start data field bit 7 to start the counter,not hr_data field.
; user can also write 1 to start data field bit 7 anytime to stop the counter, not hr_data field
; calculate your max time as an example:

;Assume your period is 1 ms = 1000 ns.
;Assume VCLK2= 12.5 ns and LRP=16 => Number of LRP (period) = 1000 ns / (12.5 ns * 16) = 5 LRP.
;In this case just program MAXC=any number larger than 5, and TIMERCOMP.data=5, TIMERCOMP.hr_data=0.

;Assume VCLK2= 12.5 ns and LRP = 32, => Number of LRP (period) = 1000 ns / (12.5 ns * 32) = 2.5
;This means 2.5*LRP or LR=2, HR=10h (16 in decimal or half LRP loop clock. Each LRP is 32 HRCLK).
;In this case, just program MAXC=any number larger than 2, and TIMECOMP.data=2, TIMECOMP.hr_data[6:2]=10h (16 dec)

MAXC      .equ   10

START      MOV32 {type=IMTOREG, reg=A, data=0, hr_data=0}
           ECMP  {reg=A, action=PULSEHI, pin=0, en_pin_action=OFF, irq=OFF, data=1, hr_data=0, cond_addr=ENCOUNTER, next=OFFSTATE }

DISCOUNTER MOV32 {type=IMTOREG&REM, reg=NONE, remote=START, data=0, hr_data=0}
OFFSTATE   BR    {event=NOCOND, cond_addr=START, next=START}

ENCOUNTER  CNT   { reg=T, max= MAXC, irq = OFF }
TIMERCOMP  ECMP  { reg=T, action=PULSEHI, pin=0, en_pin_action=OFF, irq=ON, data=5, hr_data=16h, cond_addr=DISCOUNTER, next=START }

; The ECMP instruction will generate interrupt to CPU when 1 ms comparison matches.

; Please also enable NHET interrupt and VIM.

Uploading second image since each post can only attach one file

for clarification of how 7-bit HR data field is used, please look at TimeBase section 18.4.3 Time Base, 18.4.3.2 The 7-Bit HR Data Field