DRV8313 evm R1 resistor removed

Hi Rick

Yes, i forget about the ground connection but even when i established a wire between the AGND of the ezdsp and the ground of the drive nothing is changing

 The signal for the RESET and Sleep are both generated from the dsp too, and i tried now the experiment to test the first output (OUT1), i have putted IN1, EN1, RESET and SLEEP on high logic  (the amplitude of the signal generated from the ezdsp is 3.3 v ) and i didn't forget to make the ground connection between the two boards and still don't have the output signal

Hi Sadok,

It appears like you will have to dig a little deeper.

When you set the IN1/EN1/RESET/SLEEP to a logic high, please measure the voltage at TP1 and TP3 (IN1 and EN1). If the micro is not using a strong enough drive, the internal pulldown on the pins could prevent proper operation. 

Then, please add R1 back on the board. Next, set RESET and SLEEP to a logic high and measure and report the voltages of the following pins:

V3P3OUT
FAULT
VCP

These signals will determine the next step. If V3P3OUT is 3.3V and VCP is approximately 22V, the device is awake and FAULTn could be interfering with operation.

If FAULT is low, the cause of this will have to be determined. With no motor being driven, FAULTn low is unlikely but cannot be ruled out.

Hi Rick

thanks for assisting 

but now i'm testing the TP1, i can't find my 3.3 signal but the signal is well generated from the dsp , when i disconnect the rubon cable and i mesure it , the signal is established but once i connect the two boards i can't find the signle any more (that's strange ), but the signal TP3 is ok, i fond it even when the two boards are connected !!!

(i verifed all the wires and connections and they are well installed )

have you any explanations ?

best regards  

Thanks

It's a little bit strange but when i tried the same procedure but with IN2,EN2,RESET and SLEEP,it make sense. With this configuration i mesured TP4 and TP5 and i found my 3.3 v signal on both (with DMM), ans also i measured  V3P3OUT signal , it has 3.3 v like value , VCP is 12 v (i'm giving 12 v supply on VM ? it's the same as VCP because i can't find VCP on the board) , for FAULTn , the signal is low(0 v), the OUT2 is also low 

i didn't replace R1 resistor yet, because i lost it , in case i should replace it could you give me the value (or part number for it )

best regards 

Hi Rick

Yes the procedure was the same, the signals was the same , so i can conclude that the problem is not related to the dsp signals

concerning you second remark i don't know exactly, because it wasn't me who has removed the resistors, i've a gave the board to  a friend and after he gave me back the board i realized that heommited R1 resistor (i didn't demand that !!)

For the VCP where can i mesure it (can you precise the location on the board because i can't find it )

another thing , i have connected IN1/EN1/SLEEP/RESET to an external 4.5 V and the signal i mesured were :

- TP1,=TP3=0 v

-V3P3OUT=0v 

-IN1=IN2=IN3=9.5 v 

remark , i connected the four signals directlu not through the 3.3k resistor like you proposed  

i will try to replace the resistor next week and i will try again 

best regards 

Hi Sadok,

You seem to be missing one important source of information. Please go to http://www.ti.com/tool/drv8313evm There you can find both the user guide and a zipped file under the Software heading. The zipped file contains the board schematic and layout which will help you performing debug.

The results you are reporting are inconsistent. TP1 and IN1 are the same net. How can TP1 = 0V and IN1 = 9.5V? If you are really measuring 9.5V on TP1, TP4, and TP6, the device has been damaged.

V3P3OUT = 0V indicates that either VM is not applied to the DRV8313 or that the device has been damaged. When the DRV8313 is powered up, V3P3OUT (TP2) should measure approximately 3.3V.

Please apply 12V (VM and GND) to connector J2 and measure the voltage at TP2 (V3P3OUT). If the voltage is not 3.3+/-10%, the device may have been damaged. If it is within the 3.3+/-10%, the next step is to proceed with additional debugging. What equipment do you have available; DMM, resistors, clips, etc?

Hi Rick

I'm really sorry , it was just my Fault , i meant  OUT1=OUT2=OUT3=9.5v and not IN1=IN2=IN3= 9.5 v 

i was clumsy when writing my last reply 

excuse me , i didn't meant that

i don't know may be the guy that has handled the boards has damaged it 

For the equipment i have the necessar ones i thought 

i will try to find someone to replace the R1 resistor and see 

best regards

Hi Rick 

thanks for being so patient

So, i don't know what happened exactly but now i'm measuring 9.7 or 10 v on the three output of the drive (my VM is 12 v ) but the TP2   is always 0 v .the signal i'm generating from the dsp to the 6 first pins of  J1 are in the screenshot below 

so the first signal is IN1 and the second is EN1 , same logic for the other signals

the wide band you see in the inputs signals are a pwm signal with a frequency of 20Khz

my question now is about the signals from the hall sensors , should i put them on the drv 8313 evm and the gate's  inverter will switch automatically or should i read this signals on the dsp and consider that in my program, because that,s is note mentioned is the datasheet of the drv 8313 

thks 

Hi Rick 

What i'm trying to do is to read the hall sensors signals with the ezdsp F2812 board through the analog interface and use this signals to generate the adequate signals for the drv8313 evm, (i need your opinion concerning that ) 

So my question is how can i read this 3 analogs inputs (hall sensors signals) ? i just have to put directly this three signals on the analog interface or should i put some intermediate components between the motor and the dsp pins (some resistors may be )

Just to know , i'm using matlab simulink with code coposer studio to generated  code for the dsp 

best regards   

Hi Rick

The Hall sensors signal is a digital signal , the amplitude of the signal is +5v , is it in range ?

Hi Rick

it's ok , i found the answer in the SPRAAP6A :

• The voltage applied to the ADCIN pins should be restricted between 0 V–3 V. If it exceeds this limit on
any channel, it temporarily affects the conversions on the other channels. If the signal conditioning
circuit used for the input analog signal needs to use any higher supply voltage (i.e., 5 V), it is
recommended that a buffer stage that scales this signal to < 3 V be used before connecting to the
ADCIN pin.
• If you need to monitor DC voltages higher than 3.0 V, the resistor divider should be followed by an
op-amp buffer stage. By connecting the resistor divider directly to the ADCIN pin violates low source
impedance requirement and conversion counts will see large errors

best regards 

Hi Rick

Is it normal that i measure 9.7 v on the three output of the drv8313 evm when i don't have any hight input on the J1 connector (input pins and enable pins ...), the dc supply is 12 v 

is the board damaged ?

thanks 

Hi Sadok,

I don't think the board is damaged. I have seen this behavior with a similar device. I am trying to confirm that this device behaves the same way.

Hi Rick

I was trying to test my drv with a simple, 1 phase, dc motor (i tryed the 3 outputs one by one) , the motor is running correctly but the problem that i can't control this output, it is always active even when you don't have any signal in the J1 connector I've putted 4.8 v on EN1, IN1, nreset and nsleep but it doesn't change anything , i tryed to remove some signals and keep some others but this doesn't have any effect on the output (it's the same case for the three channels)

So please , just try to confirm what should be the behavior of the drv with the configurations above? am i giving the wrong control signal ? may be i should put the others free pins of the J1 in low state? 

i'm really confused and don't know what to do 

thanks 

Hi rick,

I tried the  experiment you've recommended (Place a 1kOhm resistor to GND on the outputs and measure the output voltage when nothing is connected to the inputs) to me and the report is the following:

-For the first output, i measured 8 v , the supply voltage is 12 v

-For the second and third output, the voltage drops to less then 1 v like you've predicted, it's almost 0 v 

so as you can notice , the outputs are not the same for similar input conditions

thanks 

Hi Milan,

As a preliminary observation, i can say that we don't have similar outputs measurements for similar input conditions and i measures TP1, TP3..TP7 they are all low voltage, in despite the three outputs were hight voltage almost 9.5 v but when they are not connected to any load 

i will order a new board and see, i think that something is going wrong with the board ?

Best Regards

Sadok,

As Rick pointed out, it may not be bad device. There is possibility some smaples shows the high voltage output issue as you are observing.

At my end I will try to repeat the test on few samples that are with me and share the findings. Please allow me couple of days to do the experiments.

Best Regards

Milan

Hi Rick, Hi Milan

My new drv8313 was delivred today and i have tested it with the software of ti (i didn't remove the resistors yet ) and it works properly with ti software 

Now i will need to remove the resistors so that i can use it with the external control signal from the dsp, so what precautions i should take into account before doing that, since that the first board got damaged when removing the resistors as i thought 

Sadok,

Not anything specific, just make sure while removing the jumper resistors you do not over-heat  other components on board.

Best Regards

Milan 

Hi Rick, Hi Milan 

First of all thanks for all this explanations, and like we have predicted the problem was with the old drv because once i have  changed the drv , my motor is running and everything is normally working.

but there is something that looks strange for me  (may be i'm not understanding it very well) , in fact i'm using pwm signal to fed the coils of the motor (with a frequency of 20 kHz) , when the duty cycle is 50 % i measured a voltage average of 3.8v ,the supply voltage is 12 v, the figure below is the screen shot for the output phase voltage 

this figure below is for 100 duty cycle , the average i measured is almost 6 v

thanks for any further explanations

Best regards 

Sadok,

There is something worng with the first waveform. It's not expected results, rising back-emf portion is absent from waveform.  Typically this happens when:

1.  motor Hall-signals are not aligned properly with PWM logic , if  sensor are used

2. or Commutation is not  matched  with back-emf zero crossing  in sensor-less algorithm. I am attaching the scope-shot of phase voltage waveforms, you should  get  the same results to achive correct commutation.

Best Regards

Milan