UART EXTERNAL WRAP Transmission Issue

[rvijay435]

Hi Sir/Madam,

We are performing the following steps: 1. UART registers are configured as per 21.21 SCC UART Programming Example mentioned in the MPC8280 Reference Manual. 2. UART Buffers and Buffer Descriptors are all configured. 3. The R-bit is set in the SCC UART Transmit Buffer Descriptor which starts the Transmission. As per the description in the Reference Manual, the R bit will be cleared by Communication Processor module. But this is not happening and the data is not transmitted through the external wrap connection. We have added a timeout of 7SECS for the data to be transmitted. After 7-seconds it is coming out of the loop and displaying TRANSMIT TIMEOUT EXCEEDED. May I know what can be the cause of the issue?

[r8070z]

Have a great day,

I assume you tried to run external loopback. Let suppose that 21.21 SCC UART Programming Example was implemented properly. It means that SCC2 outputs RTS2 and tests, CTS2 and CD2. The SCC2 uses modem signals CTS2 and CD2 to enable or disable transmission and reception. You did not describe how you assign the CTS2 and CD2. Did you check that CTS2 is assigned? You may check that UART programmed properly using the local loopback, i.e. set GSMR_L[DIAG] to 01. If external loopback is preferred then, physically connect the control signals (RTS connected to CD, and CTS grounded) or set the parallel I/O registers so CD and CTS are permanently asserted to the SCC by configuring the associated CTS and CD pins as general-purpose I/O.

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[rvijay435]

Hi Podiatchev,
Thanks for response.
The issue was with the setup which was given in the remote location. So, couldn't check in person. But asked the person there to check.

Got it resolved.

Thanks.