• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 33 subscribers
  • Views 387 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Unused TXD bits on TLK2711

Pascal AVART
Prodigy 100 points

Hi,

I use only 8 bits (TXD0 to TXD7) on TLK2711 16 bit parallel interface.

I want to know   the better value to connect on the 8 unused bits (TXD8 to TXD15)  for having good transmission data and proper clock recovery.

Regards

  • 0
    TI__Mastermind 20820 points

    Hi Pascal,

    For these types of devices you always want to put your TxD pins in a known state so that they are not floating around injecting false data onto your bus. You can tie them high or low. Now, on the Rx side it is OK to leave these pins floating because if they are unused data pins and you tie them to something you may just be sourcing unneeded current and wasting power.

    Regards,

    Mike

  • 0 in reply to Michael Peffers
    TI__Guru 62930 points

    Pascal,

    A simpler approach for byte alignment and only 8bit data transmission would be to hard code the comma on the lower byte, then send your data on the upper byte.

    This will work great, as long as you can assure that you will get parity changes from your data on the MSB.

    This is required as the 2711 only does alignment on the 0011111 comma.

    If you hard code the upper byte, you will need to hard code it to cause parity change, such as a D5.6.

    An app note covers some of the underlying concerns, but not the method of only using 1/2 the buss.

    http://www.ti.com/litv/pdf/sgla001a

    I support the space version of the device.  However functionally they are the same.

    Regards,

    Wade