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stpc atlas startup problems

Posted on March 18, 2004 at 09:27

stpc atlas startup problems

3 REPLIES 3
Posted on December 15, 2003 at 14:01

Hello,

for our embedded application we use a STPC Atlas configured in ISA mode.

The design is done according to the ST Reference Design Rev. C from 27. Feb. 2002 and Hardware Manual Issue 1.0 from 24.July 2002 (esp. Boot Straps).

Now the problem: the STPC hangs during startup. We checked BIOS-Access with a Logic Analyzer. It gets the first four Bytes from the BIOS and then stops working, though all clocks like HCLK, MCLK, PCICLK are still working correctly.

(HCLK = MCLK = 66 MHz (synchronized), PCICLK = 33MHz and ISACLK = 7.14 MHz). There are also no external events, like interrupts or DMA-Requests.

The measured supply voltages are : V_Core = 2,6V and V_DD = 3,3 V.

We changed Boot-Strap-Resistors from 470k to 100k and 4k7 without effect.

Instead of the BIOS, we put a small test program in to the Flash-PROM. It's just a small endless loop, starting at address 3FFF0h with a jump and some NOPs. We then observed PCI-Control-Signals, like Frame#, IRDY#, TRDY#, DEVSEL#, STOP# and C/BE#. We observed a lot of retrys (DEVSEL# and STOP# are active) but no TRDY# active in order to complete transaction. After it performed several retys it hangs - only clocks are working.

In order to read from Flash-PROM the STPC should use a Memory Read (C/BE# = 6h), but instead it uses a Reserved Command (C/BE# = 4h).

Now, how can it read the first four Bytes of the Flash-PROM using a C/BE# = 4h ??

All C/BE#-Lines are connected correctly (C/BE# = 2h has also been observed).

Please help !

Regards

marios
Associate II
Posted on January 07, 2004 at 23:20

Do you have the Atlas demo board to make any signal comparisons?

Do you only have one board?

If you have an ISA bus, can you have your code output an I/O byte as the first instruction? Or output any simple I/O that you can control with a scope or a logic analyser? Perhaps that the CPU can't read the BIOS code properly.

jpjosse
Associate
Posted on March 18, 2004 at 09:27

Hello,

We have about the same problem on a ST-PC Vega.

Power supplies, clocks, configurators etc, have been checked.

Vega is making 4 or 8 eprom access and stops.

I freeze it, it runs normally 50 or 100 instructions...

We have 5 boards with the same kind of problem.

Very strange.

We designed a board last year with a ST-PC Atlas. We didn't encouner the kind of problem you related there. But we've been obliged to adjust PSU to 2,75V instead of 2.5V to make it reliable.

Did you fix your problem on Atlas?

I beg the IP Cell we have trouble with is the same on both processors.

Jean Pierre.