TMS320F280049: warm reset crystal oscillator behaviour

Holger,

Yes, when XRSn is asserted it resets the OSCOFF bit, which turns X2 back into GPIO18, so customer will need to go back through the oscillator start up process again.  But even WD reset should force the code back through its boot ROM/process and same setup routine as during power up.

Is customer following our clock setup proceedure from the TRM:

3.7.7 Using an External Crystal or Resonator
The X2 pin doubles as GPIO18. At power-up, it's in GPIO mode and the on-chip crystal oscillator is powered off.
The following procedure can be used to switch the pin to X2 mode and enable the oscillator:
1. Clear the XTALCR.OSCOFF bit.
2. Wait for the crystal to power up. 1ms is the typical wait time but this depends on the crystal that is being
used.
3. Clear the X1 counter by writing a 1 to X1CNT.CLR and keep clearing until the X1 counter value in the
X1CNT register is no longer saturated 1023 (0x3ff).
4. Wait for the X1 counter value in the X1CNT register to reach 1023 (0x3ff).
5. Repeat steps 3-4 three additional times.
6. Select XTAL as the OSCCLK source by writing a 1 to CLKSRCCTL1.OSCCLKSRCSEL.
7. Check the MCLKSTS bit in the MCDCR register. If it's set, the oscillator has not finished powering up, and
more time is required:
a. Clear the missing clock status by writing a 1 to MCDCR.MCLKCLR.
b. Repeat steps 2-7. Do not reset the device. Doing so will power down the oscillator, which requires the
procedure to be restarted from step 1.
c. If the oscillator has not finished powering up in 10 milliseconds, there is a real clock failure.
8. If MCDCR.MCLKSTS is clear, the oscillator startup is a success. The system clock is now derived from
XTAL.

Best,

Matthew