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AM335x DMTIMER

Stefan Beck
Prodigy 50 points
Other Parts Discussed in Thread: AM3359

Hello,

we are developing a board with an AM3359, NAND-Flash and a RTOS.

The DMTimer_1ms is used to generate the system tick and also for internal time measurement.

During the development, we found that the timer sometimes seems to make a break.

We found two problems:

1. The register TOCR was unequal <0>, but this register wasn't changed by the application (tested with IAR Workbench)

2. The value of the register TCRR was below the reload value, so the tick comes to late.

We tried in Autoreload and One shot mode.

We tried the posted and not posted mode.

We tried the other timer modules (e.g. DMTIMER2).

We split the functions: Tick with one DMTimer, Time measurement with another timer

The errors still occur.

Does anybody have an idea concerning this problem?

Kind regard,

Stefan

  • 0
    TI__Guru 63445 points

     

    A new Advisory for the AM335x Silicon Errata will be published soon that changes our original recommendation for crystal circuit grounds to only be connected to the VSS_OSC terminal.  We have found this connection topology makes it easier for noise to couple into the crystal circuit than the more traditional connection topology where the crystal circuit grounds are connected directly to the PCB digital ground.  It is possible for the oscillator to generate glitches on internal clocks if the crystal circuits have too much noise coupled into them.  So we are changing our recommendation to connect the crystal circuit grounds directly to the nearest PCB digital ground.  Try this, to see if it helps resolve your problem.

    Regards,
    Paul