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iMX28 powerup and PSWITCH issue

Question asked by Nicholas Ipri on Mar 11, 2012
Latest reply on Nov 8, 2012 by samuel salas

Hi, I am bringing up an iMX28 design that uses a single 5v supply and no battery. I have the PSWITCH input tied to the 5v supply through 2 resistors and a cap to GND in a "T" configuration. When I power the board, the iMX starts to boot from the SD card but doesnt get through configuring and enabling the DC-DC converters before rebooting. Also, I've noticed that the 22 MHz crystal is not running. Freescale tech support tells me that my PSWITCH configuration shouldn't be the problem but I've gone through just about every line of the power_prep.c bootlet and it appears that everything is OK there. (I did uncomment the #define for 5v only operation) and I also applied the patches to power_prep.c for 5v only operation. I need the iMX28 to power up and boot reliably whenever the single 5v supply comes up and will have no button / switch /etc to control PSWITCH so I need to do something to reliably control PSWITCH or tie it to a voltage (VXTAL?) Anyone have any similar experiences? I've read a couple of other posts that relate to this problem but found no solid solution. Thanks! 

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