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AM3703 - INT1 permanent low

Thomas Leidenfrost
Prodigy 250 points
Other Parts Discussed in Thread: AM3703, TPS65951

We got this issue with approx. 15% of our new manufactured boards, which are unprogrammed. What we already know:

Supply voltages present: VDD1 & VDD2 = 1V2, VIO = 1V8, VRTC.OUT = 1V5. VBAT is ~ 3V8

26 MHz Clock present at PMU 2-3 ms after startup, 32.768 kHz RTC-Clock present at PMU

CLKREQ from AM3703 to PMU is HIGH (not active)

PMU (TPS65951) NRESWARM & NRESPWRON are HIGH (not in reset)

That means power sequencing as in datasheet chapter 6.5.4.2 is complete & fine

We have no external RTC, no USB present, no charger present,

Boot Mode is set to Master (Boot1 with 10k pull-down o GND, Boot0 with 10k pull-up to VBAT (3V8))

Here is a part of the schematic:

I would like to know why INT1 at some of our boards is permanent low, after power up. The system does not boot

The only output at Uart3 is

U-Boot SPL 2012.07 (Oct 25 2012 - 10:13:30)
Texas Instruments Revision detection unimplemented

Than nothing happens, INT1 keeps low.

This indicates the processor has no software, but the software is present on a SD card (working on other boards)

Thanks for any hint

Thomas

  • 0
    TI__Guru**** 393215 points
    Hi Thomas,
     
    Judging from the message output on UART3 your board enters u-boot, but crashes somewhere in the beginning. I strongly suspect that you may have a memory issue - either manufacturing defects or memory settings that are marginal. It probably isn't a design error, since you say that 85% of your boards work OK. I would suggest you investigate in these direction, maybe debug where u-boot crashes, if possible.