[U-Boot-Users] RE: Determining the UPMA. UPMB SDRAM table

Keith Outwater Keith_Outwater at microvision.com
Wed Sep 17 19:21:07 CEST 2003

> -----Original Message-----
> From: Raghu [mailto:raghu_dk at yahoo.com]
> Sent: Tuesday, September 16, 2003 8:30 PM
> To: u-boot
> Subject: [U-Boot-Users] Determining the UPMA. UPMB SDRAM table
> Hello,
> Just courious to know how does one determine the SDRAM
> table to MPC8xx family of processors ??
> Warm Regards
> Raghu.

Raghu - 
As Robin Gilks pointed out in another post, Motorola has a tool called MCUinit on their web site that also includes a tool called UPM860.  UPM860 allows you to graphically edit the SDRAM timing waveforms and then generate a UPM table.  Very handy (I used UPM860).
I also found Motorola application note AN2066/D very helpful when designing my SDRAM hardware interface and writing the UPM tables and SDRAM init code.

Finally, take a look at the SDRAM initializations of 860 based boards in the U-Boot sources.  You can get a good head start by doing this and depending on the SDRAM you use, you may be able to copy the UPM tables and initializations. Many SDRAMs from different manufacturers use the same or similar init sequence and timing.

Just remember that if you copy the UPM tables from another board, be sure to determine which UPM outputs are connected to which SDRAM pins.  The MPC860 provides a lot of flexibility in this area and different hardware designs may use different pin assignments.  Read your SDRAM datasheet carefully and implement the required initialization.

One final tip:  if you copy the UPM tables, feed the tables back into UPM860 and you'll get a graphical representation of the timing. This reverse-engineering step will allow you to see what's going on and make any changes that may be appropriate for your particular hardware.

The port I did of U-Boot to my generic MPC860T design (GEN860T) may be a possible starting point.  I tried to make the SDRAM init clear and straightforward.

Hope this helps,

Keith Outwater
Sr. Staff Engineer
Microvision, Inc.
19910 N. Creek Parkway
Bothell, WA 98011

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