TMS320F28335: TMS320F28335

Hello,

Please refer to the device TRM, Chapter 4.2.4 Scale Factor Optimizing Software (SFO) for more information on SFO_TI_Build_V5.lib.: www.ti.com/.../sprui07.pdf

Hi, 

Thank you for the TRM. I gone through the document could you explain the snippet code in page-339 of TRM.

main()
{
// User code
// Case1: ePWM1,2,3,4 are running in HRPWM mode
SFO_MepEn(1); // Each of these of function enables
SFO_MepEn(2); // the respective MEP diagnostic logic
SFO_MepEn(3); // and returns MEP Scale factor value
SFO_MepEn(4);
MEP_ScaleFactor1 = MEP_ScaleFactor[1]; // used for ePWM1
MEP_ScaleFactor2 = MEP_ScaleFactor[2]; // used for ePWM2
MEP_ScaleFactor3 = MEP_ScaleFactor[3]; // used for ePWM3
MEP_ScaleFactor4 = MEP_ScaleFactor[4]; // used for ePWM4
// Case2:ePWM1,2,3 only are running in HRPWM mode.
One of the ePWM channel(as an example ePWM4) is used as for
Scale factor calibration
// Here minimum duty cycle limitation is 3 clock cycles.
//
// HRPWM 4 MEP diagnostics circuit is used to estimate the MEP steps
// with the assumption that all HRPWM channels behave similarly
// though may not be identical.
SFO_MepDis(4); // MEP steps using ePWM4
MEP_ScaleFactor1 = MEP_ScaleFactor[4]; // used for ePWM1
MEP_ScaleFactor2 = MEP_ScaleFactor1 // used for ePWM2
MEP_ScaleFactor3 = MEP_ScaleFactor1 // used for ePWM3
MEP_ScaleFactor4 = MEP_ScaleFactor1 // used for ePWM4

From the code above i am assuming in the infinite loop if we run the line below (it will execute in every loop i.e.. every 100 us)

SFO_MepEn(1);

it will optimize the MEP_scaleFactor value over few cycles. Once attains the optimization it will transfer the new value into the MEP_ScaleFactor variable. 

Am i right in understanding please correct me?

suppose if we read the MEP_ScaleFactor before optimization what value it will give?

Regards,

S. Balaramkumar

Hello,

In the code snippet, the MEP_ScaleFactor variable is updated with the optimized value only after the MEP diagnostic logic is enabled for ePWM channel 4, and the value is calculated using the HRPWM 4 MEP diagnostics circuit. This suggests that the MEP_ScaleFactor variable is updated after the optimization process is complete.

So, The MEP_ScaleFactor variable stores the current value of the MEP scale factor. The SFO_MepEn(1) function reads the current value of the MEP_ScaleFactor register and returns it as the MEP scale factor value.
The MEP_ScaleFactor variable is updated dynamically as the MEP diagnostic logic is enabled and disabled, and the MEP scale factor value is optimized.
If you read the MEP_ScaleFactor variable before the optimization process, it will give you the initial value of the MEP scale factor, which may not be the optimal value.

Hi, 

The problem is MEP_ScaleFactor[5] goes to 32767 when we use SFO_MepDisV5.

From earlier TI forum discussions it is found the problem is due to library file SFO_TI_Build_V5B_fpu version.

If i use the library SFO_TI_Build_V5_fpu, SFO_MepDisV5 is working fine and gives the optimization values same almost during running.

so final conclusion is with library file SFO_TI_Build_V5_fpu, both SFO_MepDisV5, and SFO_MepEnV5 are working fine.

with SFO_TI_Build_V5B_fpu only SFO_MepEnV5 is working fine.

With regards,

 S. Balaramkumar

Hello,

TMS320F28335 is older device, please use Gen3 device to avoid any issues with libraries and optimization.

Regards,