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Rx Error When running two UCCs in Parallel

Question asked by Subash Rajaram on Jun 23, 2017
Latest reply on Jun 26, 2017 by Subash Rajaram

Hi Folks

We are using MPC8309 as well as MPC8321 in our project. Here I have two questions

1) When I use two UCCs in the SDLC mode simultaneously then I see One of the UCC has the Rx Packet drops and in other one there is no such a loss.

When I explore on this, there is Rx Interrupts at all. So I Dumped the Buffer descriptors. The length field is not updated. The expected value of the Buffer descriptor in case of no reception is 0x9000 but the value obtained is 0x9c00. So I am considering that F and L bit are set by the RISC but the legth is not updated. What may be the Reason? If I run the Single port alone, then there is no such a Rx loss.

 

2) The Control Signals CTS, RTS and CD should be shorted if we use the UCC in Loop-back mode or else those signals should be driven according to the third party device. But the requirement is to run the ports in HDLC mode without shorting the CTS/RTS/CD pins. \

So we tried by configuring those pins as GPIOs with the following values.
For Example, I am using UCC2 . Following are the pins and their corresponding CPPAR and CPDIR values.
PINS: PA26, PA28 and PA30
CPPAR_REGS: 00, 00 and 00
CPDIR_REGS: 11, 11 and 11

But the loopback fails. Are we doing anything wrong?

Thanks in advance.

alexander.yakovlev

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