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UCC data rate support on tdm interface

Question asked by padmayarraguntla on Sep 21, 2016

we are using p1021 in one of our projects. here we would like to transfer data from Ethernet port(eTsec) to TDM port  using HDLC protocol. Here core is operating at 666mhz and quicc engine is running at 333mhz.Our application  insists data transfer at 40mbps. we have  configured the UCC  for fast mode. As per data sheet, TDM bus can work upto 333mhz/8 .ie is 41.625mhz.we disabled the all other peripheral communication on quicc engine.


we want to evaluate the TDM bus data transfer rate, For that we have enable  PPPD. In PPP configuration file we have set the  LCP- Restart  interval as  0.01msec.The PPP configuration file and screen shot of log data  while booting the Processor attached for your reference.


with the following settings our observations are as below


tx packet count is enabled and trans time  in the code .


PPP config file is set to

LCP_Max_configure      :10000

LCP_MAX_failure         :10000

LCP_MAX_terminate   :10000

LCP_Restart              : 0.01msec


 1. we have  observed that tx packet count 10000, which is matching with PPPconfig file.

packet length               :26bytes.

packet repetition          :  0.01msec

trans time  for 10000 packets has taken :92msec

data transfer per 92msec  : 26bytes*8*10000 =2.080mbps

data transfer per 1sec         :22.60mbps


2. Now changed the LCP_Restart time  to  :0.005msec.

      with this setting ,we observed that data transfer time for 10000 packets has taken :76msec

so data transfer rate as per above calcutions is: 27.368mbps

 As per the settings it should come 41.6mbps.but  observed that it is giving 27.3mbps. Please clarify , why this is not working as per programming.




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