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sync ports port E configuration

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Hi all;

We are using the RCM5700 module and We would want to use the serial port E as sync. The pinout definitions is as follow:
*PE6 as TXE
*PE7 as RXE

TXE is an output and RXE is an input.

When in our device we are talking about internal clock, TCLKE & RCLKE are outputs and the clock is generated by Rabbit timers. But with external clock, could be some of next two configurations:

*TCLKE & RCLKE external. The RCM will receive the clock
*RCLK external and TCLKE internal (generated by Rabbit)

Is that posssible these configuration?

How would it be do?

When on the register SECR we configure as external clock (bits 3:2->10), are TCLKE & RCLKE inputs?

asked Feb 16, 2015 in Rabbit Software by jlrubio New to the Community (7 points)

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1 Answer

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From what I can see in the documentation for the Rabbit 5000 serial ports:

Short answer - No, the serial clocks options in HDLC mode seem to allow for internal OR external source for BOTH clocks but not a mix of internal for one and external for the other.

Longer answer - you could possibly achieve what you want by selecting external clock mode and generating the TCLK using one of the Rabbits timers fed to a port pin and linked externally to the correct TCLKE input pin.

To do this, you would need to have some gating logic and a control pin to switch between external TCLKE source and the "internal" source. You will also need some external logic with a tri state buffers to disconnect the two external clocks when in internal clock mode so that you are not trying to drive an output signal to another output signal..

answered Feb 18, 2015 by petermcs Veteran of the Digi Community (1,132 points)