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TMS320F28377S: Synchronous Data Transfer

Ankit Srivastava
Expert 1160 points
Part Number: TMS320F28377S


Hi,

I am interfacing TMS320F28377S to one of the transceivers which provide/need the following 4 set of RS422 signals:

1. A Data signal and a Clock signal for Transmit  (both signals are provided by the TMS320F28377S to the transceiver)

2. A Data signal and a Clock signal for Receive (both signals are provided by the transceiver to the TMS320F28377S)

All signals are RS422 (so I need RS422 converters). The data signal is synchronized with the Clock signal.

What peripheral can I use for this kind of transfer?

I was thinking of McBSP first, but it seems like there is an extra signal Frame Sync which is not needed in our case.

Any suggestions or alternative peripherals for the above scenario?

Thanks and Regards,

Ankit

  • 0
    Guru 30330 points
    Ankit,

    I am sure that you remember your post on this topic from Jun 2017: e2e.ti.com/.../601712
    Were you unsuccessful in your attempts up to this point?

    It appears that the using and external CLKR source and an internal FSR source is not valid. I am looking for further confirmation of this and will let you know.

    Your other option is to possibly use two instances of the SPI module - one is the Transmitter, the other is a receiver.

    Again, the issue with even the SPI receiver case is synchronization. If you ever lose sync between the transmitter and receiver, you don't have a good way to recover. This is what the FSR for McBSP and SPISTE for SPI are used for.

    -Mark
  • 0 in reply to Mark Labbato
    Guru 30330 points
    Ankit,

    I have had some confirmation that the McBSP needs the FSR to correctly synchronize frames. It needs to be generated somehow. If the TX and RX are expected to be synchronized, is it possible to wire up FSX to FSR and provide the pulse that way?

    In any case, Both SPI and McBSP need these frame sync pulses (SPISTE, FSR respectively) to preserve synchronization between the transmitter and receiver. Without it, you are opening up the channel to accumulate errors over time.

    Regards,
    Mark
  • 0 in reply to Mark Labbato
    Expert 1160 points
    Hi Mark,

    Regarding Jun2017: e2e.ti.com/.../601712
    At that time I was new to the chip and was trying to understand McBSP and RS422/RS485 which I had never worked with before.

    I am interfacing TMS320F28377S to a communication transceiver which has Synchronized data with clock for it's transmitter and receiver as well.
    Both are separate blocks each having two wires (clock and data) and none of the existing protocols fit in nicely. SPI requires at least three wires whereas I2C is two wired but needs and address on data line. Is there any two wired protocol which just have synchronized data with clock? Is it called USART?


    Regarding "I have had some confirmation that the McBSP needs the FSR to correctly synchronize frames. It needs to be generated somehow. If the TX and RX are expected to be synchronized, is it possible to wire up FSX to FSR and provide the pulse that way? ", I think this means that whenever I start receiving clock and data from the communication transceiver, I need to generate a pulse on FSX which will generate a pulse on FSR. This will need another synchronization where I have to generate the pulse just before the receive start. I have to check on this.

    If I use SPI then I always need to use two different modules and their STEs (corresponding to FSX and FSR) have to be connected together I believe.

    I think this will still take time for me to understand. But I am very thankful for the support.

    Thanks and Regards,
    Ankit
  • 0 in reply to Ankit Srivastava
    Guru 30330 points
    Ankit,

    I think I understand what you are saying- your transceiver has clock and data for each transmitter and receiver. total of 4 wires. two in each direction. the C2000 I2C has a free data format mode, where no address is needed, but there are framing bits needed - START, STOP, and ACK/NACK.

    My previous suggestion is to use the FSX to drive the FSR, but your data packets would need to be synchronized.This means that when the transmitter starts a frame, the receiver should start a frame too.

    If possible, can you please share the external device you are communicating with. A wiring diagram with the transceiver in the path would be beneficial as well.

    Regards,
    Mark
  • 0 in reply to Mark Labbato
    Guru 30330 points
    Ankit,

    Any updates or followup questions?

    Regards,
    Mark
  • 0 in reply to Mark Labbato
    Guru 30330 points
    Ankit,

    It has been another week since you last replied. I am going to close this thread. If you have additional questions on this topic, please reply here. If you have questions on a different topic, please go ahead and create a new thread.

    Thanks,
    Mark
  • 0 in reply to Mark Labbato
    Expert 1160 points
    Hi Mark,

    Sorry for the late reply. I was on a long leave and I haven't moved forward on this. This month I will be working on the interface.

    Thanks and Regards,
    Ankit