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Reading back a 10Mhz digital signal in Hercules micro controller

NEERAJ KUMAR
Intellectual 355 points
Other Parts Discussed in Thread: SN65HVD3088E, SN65LVDS180, SN65MLVD204A, SN65HVD78

Hello,

I have been able to generate the digital signal of 10Mhz frequency using ePwm module of Hercules micro controller.
I have a question for you.

Actually, i am generating these digital signals to send through tx pin of CAN transceiver and see the response on rx pin of same transceiver.
I have to compare these values bit-by-bit.
I am thinking to read back the tx values on some pin of this microcontroller and then compare both tx and rx. 
But, i am not sure i will be able to read back through rx pin on such high frequency (approx 10Mhz).

I experimented with DCAN module as well and changed the bit time to operate it on higher than 1 Mhz. But, I was able to do only upto 3 Mhz.


If i could do that, i also don't know the way of doing this.
Can you please guide me in this regard and if there is some other way i would like to know.


Thanks,

Neeraj

  • 0
    Expert 1285 points

    Use SPI, it supports up to 20 MHz baud rate.

    MibSPI mode can buffer 128*16 bits (TX & RX). When the whole TX is done you can compare the TX & RX buffers to verify the loop.

  • 0 in reply to Joe Josn
    TI__Guru**** 191486 points
    Hi J,
    Your idea is viable.

    Neeraj,

    I don't know the intended application. Is this a test for the transceiver? You should also check your transceiver what is the maximum data rate it can support.
  • 0 in reply to Charles Tsai
    Intellectual 355 points
    Yeah it's for test of transceiver.

    Regards,
    Neeraj
  • 0 in reply to NEERAJ KUMAR
    TI__Guru 68920 points
    Neeraj,

    I saw that someone moved this post to the Hercules forum.

    Did you post to the CAN transceiver (Interface) forum like I suggested?

    If so they may have seen 'Hercules' and just moved it here.

    I would rephrase the question and simply ask if the CAN transceiver can
    transport a generic 10MHz PWM over CAN bus type wiring.
    Don't mention any MCU for this question. You just need to know if the
    transceiver/wiring can pass your signal of interest or if there is a better choice.
  • 0 in reply to Anthony F. Seely
    TI__Guru 62920 points

    Hi Anthony, Neeraj,

    I'm from the Interface forum, and I may have moved this post over too hastily.  (I didn't see a transceiver part number specified, so I thought that it was a general question about the Hercules MCU.)

    CAN transceivers are typically rated for lower speeds - 1 Mbps for "classical" CAN and up to around 5 Mbps for CAN FD.  There may be some higher-speed transceivers out there for more specialized (non-automotive) applications, but I don't know of any devices from TI currently that would be able to support a 10-MHz PWM.  The higher speeds are a challenge with CAN due to the dominant/recessive signaling (which does not strongly drive both differential edges) and the relatively strict EMC requirements of most CAN applications (which tend to benefit from slew-rate-limited edges).

    Max

  • 0 in reply to Miguel Robertson
    TI__Guru 68920 points
    Thanks Max,

    This is what I suspected but was thinking perhaps one of the LVDS transceivers might be suitable.. (if not overkill)
  • 0 in reply to Anthony F. Seely
    TI__Guru 68920 points
    But being an MCU guy I figured this is a better question for the interface team ;)
  • 0 in reply to Anthony F. Seely
    TI__Guru 62920 points
    An LVDS device could certainly support the speed needed. Since LVDS is typically used for one-way (simplex) communication, you would need a device like SN65LVDS180 that includes both a transmitter and a receiver that could be tied together on the bus interface. Something slower like an M-LVDS part (for example, SN65MLVD204A) or a higher-speed RS-485 transceiver (for example, SN65HVD3088E or SN65HVD78) could likely be used as well.

    Best regards,
    Max