Boot problems with OMAP L138B

Hi Andreas

Do you have a TI local field/sales office contact that could be assisting you on this issue?

Regards
Mukul  

Hi Mukul,

I have already contacted my local office with this issue, but there was no response yet.

Thus, I had the hope, that I could some get some help by the forum.

Regards,

Andreas 

What is the state of TRST during the boot? I cant see it on the schematic, but is it pulled low?

On the failed boot, have you connected in CCS using the debug GEL to verify that the wrong boot mode was in fact latched?

Jeff

Hi Jeff,

instead of using CCS for debugging, we use a Lauterbach debugger. My SW colleague verified that the boot mode is wrong because the value in the BOOTCFG register is 0x1Eh.

The \TRST has an external pullup (blue line). So, every reset is like a warm reset.

It seems, that this wiring is an error !

It seems that with the rising edge of the \TRST the wrong states of the boot pins are latched caused by the glitch.

As all following resets are warm resets, the wrong boot mode is not changed. 

After your post, I´ve made to two tests:

a) connecting the \TRST hard-wired to GND

first, the wrong boot mode was latched, after the reset of the watchdog the OMAP booted correctly

b) removing the pullup resistor and the wire to GND and leave the pin floating

first, the wrong boot mode was latched, after the reset of the watchdog the OMAP booted correctly

In both tests at first the state of the boot pins was high, so the wrong boot mode was latched.

After the rising edge of the reset, the state of the boot pins went low and the OMAP booted correctly.

It seems that a warm reset doesn´t re-latch the boot pins by the rising edge of the reset.

I think we have different options now:

i) connecting the \TRST pullup to GND

ii) using a pulldown resistor instead of the pullup resistor (\TRST)

iii) leaving the \TRST pin floating

iv) using a strong pulldown resistor (<1k)  instead of  the 10k at the boot pins

Option ii) is a long-term solution because it requires a redesing of the PCB

Option i) is possible but it requires an additional wire soldering by hand -> higher manufacturing costs   -> not the prefered solution

Option iii) is possible but it is no good solution !

Option iv) is maybe the best short-term solution for our problem.

If you or anybody else has further more solution, please feel free to post it  ;-)

I´m grateful for any other solution !

Andreas

Andreas, yes TRST must be pulled down to boot properly every time. See the following document for details:

http://processors.wiki.ti.com/index.php/OMAP-L138_Bootloader

So are you saying that even with TRST tied to ground, the board still failed to latch the correct boot mode when powering up? Can you provide a scope shot of this scenario, including RST, TRST, and one of the low boot pins?

Can you connect with your emulator after the failed boot and read the memory location 0xFFFF0700?

Thanks,

Jeff

Andreas

Option iv looks good. I am also trying to get hold of the local team supporting you on this, that way if you have any additional issues/concerns or if we missed any failure details here, we will be able to close with you further on a one on one call.

Regards

Mukul