PGA411Q1EVM: A noise is introduced when an arduino board is connected

UPDATE:
The noise gets reduced by a considerable amount when I remove the NRST and FAULT pins. But the remaining noise gets cancelled only when I remove the SCLK pin from the Arduino. But I need the SCLK pin in order to establish an SPI communication between the two boards!!

Ranitha,

Ranitha Mataraarachchi said:

Part Number: PGA411Q1EVM

Hello,

I'm trying to read the Angle data from a PGA411Q1EVM via SPI communication. The motor being used is the REMY HVH250 3-phase permanent magnet motor. So far I can read the angle through the GUI without any issue. And no noise is present in the Data Monitor of the GUI. There are no Fault flags triggered. 

 

But as soon as I connect my Arduino Uno to the SPI pins of the EVM module there is a huge noise introduced. I tried using several Arduino boards but the issue still remains. 

The pins I'm connecting are,

NCS, SCLK, SDI, SDO in the J11 header with their respective counterparts in the Arduino Uno. Also, I'm connecting FAULT and NRST pins to two digital pins in the arduino board.

Any insight into this would be highly appreciated, 

Regards,

Ranitha

UPDATE #2:

I've found out that the problem for the noise is SCLK pin. When I disconnect it the noise gets cancelled. I have set the SCLK below 8MHz which TI recommends. I can't proceed further with SPI due to this noise. 

Ranitha Mataraarachchi said:

Part Number: PGA411Q1EVM

Hello,

I'm trying to read the Angle data from a PGA411Q1EVM via SPI communication. The motor being used is the REMY HVH250 3-phase permanent magnet motor. So far I can read the angle through the GUI without any issue. And no noise is present in the Data Monitor of the GUI. There are no Fault flags triggered. 

 

But as soon as I connect my Arduino Uno to the SPI pins of the EVM module there is a huge noise introduced. I tried using several Arduino boards but the issue still remains. 

The pins I'm connecting are,

NCS, SCLK, SDI, SDO in the J11 header with their respective counterparts in the Arduino Uno. Also, I'm connecting FAULT and NRST pins to two digital pins in the arduino board.

Any insight into this would be highly appreciated, 

Regards,

Ranitha

Hi,

Please monitor OSIN and OCOS signals on the scope before and after connecing the Arduino. If you notice the noise on these signals, this will translate to angle error. 

Please check whether the grounds between the PGA411 and Arduino are connected or not. Make sure that the ground is not bouncing when there is  communication happening through Arduino.

Regards

Sharath.