DRV8873HEVM: problem about Fault pin

Hello!  

1)  Please see table 13 in the datasheet for fault response that would result in the nFAULT pin reporting LOW condition.  Is the light on in the GUI or on the EVM itself (physical nFAULT LED is lit)?  How much current are you seeing in the motor when this occurs?  If you can capture the current waveform with a current probe, that would be helpful.

2)  Frequency is fixed in the firmware and can only be adjusted by modifying firmware.  Should be fixed at 20kHz. Ramp rate is the number of PWM cycles to move from current duty cycle setting to the a new one selected with slider.  This gives some delay instead of immediately moving to increased of decreased duty cycle setting.  

3)  On the DRV8873H, the current limit is fixed at 6.5A.  See section 7.3.3. in the datasheet.  For the DRV8873S, there are 4 levels selectable with SPI registers.

4)  You need to set the Rsense in the GUI equal to the resistor on the EVM board.  The default should be what comes installed on the EVM.  If you change this resistor, then change the values in the GUI to match so the current is properly displayed in the GUI.

Hi Ryan,

Thanks for your help ! I will try what you said.

One more question, Do we have a software development program for DRV8873HEVM? My customer likes to change the chopping frequency when changing directions, he wants to modify it directly in the software program

BR

Jenson

Thanks you for your help! when I disable the OLD ，the EVM not show errors. Is this a problem with the EVM software?

At the same time, I am very interested. In PWM mode, I set IN2 duty=0 and increase IN1duty. This is the case when the waveform before the motor is not started. Why does this happen?

BR

jenson

Thanks you for your help! when I disable the OLD ，the EVM not show errors. Is this a problem with the EVM software?

At the same time, I am very interested. In PWM mode, I set IN2 duty=0 and increase IN1duty. This is the case when the waveform before the motor is not started. Why does this happen?

BR

jenson

Jenson,

For the OL issue, lets try one more thing.  Leave it as "activated" like you did before, but after motor is working, try taking nSLEEP pin LOW and then back to HIGH.  This should reset the OL flag and I want to see if error goes away on nFAULT.

For the PWM operation, this is expected behavior.  Please see table 5 on page 15 of the datasheet.  You are fixing IN2 = 0 and PWM'ing IN1.  When IN1=IN2=0 volts, the outputs go to HIZ state.  

What you should do instead is fix one of the inputs to HIGH state, "1", and PWM the other input.  Then you will go between a "drive" state and a "brake" state.  The brake state is when both inputs equal "1".  If you want to change direction, force opposite PWM input to "1", and PWM other input.  Please study table closely and figure 10 in the datasheet describing states.  It should then make sense.

Ryan,

Thanks for your help!

I will ask my customer to try what you said, and I would like to double check in my PWM mode ,the picture show is on Hi-Z status, it is a normal status,right?

thanks for your help again!

BR

jenson