TIVA documentation in the section on configuring GPIO for EPI use with the SDRAM option mentions configuring the GPIO ports for alternate function select (EPI), 8mA drive strength, and slew rate control. I am testing a 129 connected to an AS4C4M16S SDRAM; the SDRAM controller completes its initialization but I am unable to read/write to the part (always reading 0s). Bus us at 60 MHz. GPIO lines appear to be set up correctly, a dump of the GPIO control registers shows them to be in the proper mode (8mA, alt fctn selected, port control F).
Is there a reference for further guidance on GPIO setup? For example, do all EPI pins tied to the SDRAM need to have 8mA and slew rate control enabled? (In the absence of other info, that is what I have done). Is there a more specific order of setup? And, do the pull up or pull down features on the port need to be enabled? (Do they even apply once alternate functions are enabled?)
Thanks much!
