sync ports port E configuration

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?


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…