SCI Problem: Rx-Tx

[saurav]

Hello Forum!
I am trying to develop a program related to SCI.
I am using Codewarrior IDE. Target is P&E Multilink CyclonePro. I have a MC9S12XDT256-based development board. For debugging (using BDM), I use WinIdea2006 (ic3000HS emulator).
The logic I try to implement is as follows: A tester keeps on sending a sequence of bytes to the controller over SCI1 at 4800 baud. On receiving & recognising the correct pattern, the controller sends back an acknowledge at the same baud. On receiving the acknowkledgement from the controller, the tester stops sending the start/wake-up pattern & actual communication starts. SCI1 is given to K-Line. This means that the communication is finally through K-Line.
The tester is working fine. I receive the start pattern in the controller. Then I send the ack. byte.I put the byte on SCI1DRL after reading SCI1SR1 while TDRE is asserted.
Till reception, everything is fine. Once I send the data, the Tx interrupt takes really long time & COP-service triggers a reset. My loop time is 10ms & COP reaction time is around 52ms.
Also I see that the tester keeps on sending the wakeup sequence even after I send the ack. byte from the controller. This means that the tester is not receiving what I am sending.
Any help on what might be going wrong with the Tx will be highly appreciated.
With warm regards,
Saurav

[YeOldeBDM]

We designed a product using an HCS12 processor (A128B) and had to work around an problem with the silicon- Cannot use TX and RX interrupt on one SCI channel.

Check the errata sheet for the processor you are using.

[Lundin]

That should only apply to the old B mask sets that are not longer made. The OP is using S12X.