[U-Boot-Users] Problems with serial output on custom MPC8280 board

Georg Klug gklug at giga-stream.de
Sat Aug 9 00:09:06 CEST 2003

Hi all,

we developed a custom board with a MPC8280 PowerQuiccII. It has the serial
console on SCC3. We already ported the U-boot 0.4.5 (based on the MPC8266 board)
to it and it works fine after a Power-on-Reset. The trouble begins when we issue
a HRESET. (We usually do this with the BDI2000 box). After this HRESET the
serial console occurs to hang randomly. This mean that the U-Boot code hangs in
the while loop of serial_putc() function where it waits for the first character
to be sent to the console. But unfortunately the BD_SC_READY gets never
 In this situation we tried to reset the CPM manually (with BDI box) once again
with the following sequence:
- Issue the RESET Command to the CPM
- Set register sccm, scce, gsmrh, gsmrl, and psmr for SCC3 according to the
  in serial_init.
- Issue the TRX_INIT command to the SCC3. The command was accepted by the CPM
  CPM_CR_FLAG was reset when we re-read the cpcr) We also verified the the dpram
  parameter portion had the same contents as in the "good working case".
- Enable the transmitter and receiver via gsmrl register.

But the serial console did not react and the BD_SC_READY was not cleared. No
further HRESET could then solve the problem. Only after POR the console showed
some output again.

 This leads us to the impression that somehow the CPM/SCC3 could not properly
communicate with the CoreCPU. Does anybody experienced a similar problem?

Any hints would be very much appreciated.

Kind regards,

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