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TMS320F28069M: How to use the 80 pin TMS320F28069M to drive two motors, pin conversion from the 100 pins package to 80 pins one

Part Number: TMS320F28069M
Other Parts Discussed in Thread: DRV8305, TIDA-00643, , TIDA-00916

Good morning, 

I am trying to design an ESC which is able to drive two motors independently with the same MCU, TMS320F28069M, in my case as the minimum area is the main concern I have decided to try to use the 80 pin package to drive both motor driivers (DRV8305) and sense the voltage and currents of the half bridges. I am planning to use an SPI bootloader. The main objective is to design a similar board as the TIDA-00643,same driver,MOSFETS,  power and protection but with the  TMS320F28069M processor which is able to drive two motors. 

Based on both TIDA layouts provided i am trying to connect the pins of the MCU with the drivers and I have few questions:

 

I have three questions, 

1) the first one is related with the VSEN of PVDD as in the 100 pin packages is done by adcina7 but in this case this adc is not available in this package, it is needed to test this pin or is not needed?

2) EN_GATE for both drivers, 1 and 2 in TIDA-00916 is connected to GPIO50 and GPIO53 which are not available in the 80 pin package, there is any other alternative GPIO port that i can use?

 

3) Similar problem I have with the DAC which are connected to GPIO40, GPIO41, GPIO42 AND GPIO43. I am not completely sure if the DAC signals are needed or it is only for testing purposes?

Thank you in advance

Kind Regards

  • 1. Yes, it's for dc bus voltage sensing, you may connect to other ADC pins, or just use one for two motors.

    2. Yes, you can use any spare pins instead of these two pins.

    3. Yes, it's not necessary for a product, just for debugging during development.

  • Thank you very much for your answer, it is very useful. 

     I have some extra doubts with respect the ADC pins:

    If i have three current sensing pins and three voltage sensing pins per motor and two motors, there is a total of 12 pins needed which is the total ADC pins that i have available in the 80 pins package. Therefore, I do not really have space for any Vdc sensing. I could measure the voltage sensing in only two terminals of the motor, however i am afraid there will be accuracy looses. Am I correct? 

    Thank you in advance

  • No, three-phase voltage sensing is necessary for instaSPIN. You might use 2 current shunts if you don't need to implement the overmodulation to get the high speed.