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AM5728: EVM not booting

SAJEEVAN K8
Intellectual 330 points
Part Number: AM5728
Other Parts Discussed in Thread: TPS659037

Hi,

 

I have a newly purchased AM572x EVM.

I have been working and testing on it for more than one week now.

But from yesterday it is not booting up. When I am connecting the serial debug cable and using putty software, no messages are coming in this.

The LED D3 is glowing for 10seconds and then it is OFF.  But the main power LED D41 is continuously glowing.

We check the voltages at pin no 1 of U2, it is continuously 3.3V, but at output 8,  voltage is initially 3.3V, after 10 seconds it becomes 0.

The signal VDD_3V3_ON signal from PMIC(TPS659037) also is HIGH initially and LOW after 10seconds.

How can I make this normal. Whether this is because of Hardware problem or software problem. (TPS659037 is a programmable IC)

 Thanks for the help in advance.

Thanks & Regards,

Sajeevan.K

  • 0 in reply to Biser Gatchev-XID
    Intellectual 330 points
    Hi Biser,

    Thank You very much for the reply.
    To disable PMIC shutoff we shorted J5 connector.
    But still there is no messages in serial debugger.

    Another thing we noticed is that the IC TPS659037 is very much heated up, when J5 is shorted.
    Any suggestions to solve...

    Thanks in advance for the help.

    Thanks & Regards,
    Sajeevan.K
  • 0 in reply to SAJEEVAN K8
    TI__Guru**** 393215 points
    What is your boot source? Have you set the boot jumpers accordingly? Note that shorting J5 is not recommended for long periods of time.
  • 0 in reply to Biser Gatchev-XID
    Intellectual 330 points
    Hi,

    1) Boot source
    My boot source is sd card.

    Even with SD card with pre built images this problem is happening.

    But I have been changing am57xx-evm.dts file pinmux settings to make GPIO and UART working.
    I had put some wrong values of offset in pinmux settings in this .dts file. The corresponding .dtb file, I loaded in the SD card.

    Would a wrong .dtb file permanently damage the card like this? Problem started when this SD card was placed in EVM.

    But after that I replaced the SD card with prebuild images from SDK. Then also the same problem is happening.

    2) boot jumpers

    boot jumpers in J3,J4 & J6 are connected so that, 2&3 are shorted in all.
    It was like this, when I get the board, and not changed.
    After getting board, 5-6 days it was working fine, and for the last two days only, the problem started.

    3) One additional information

    GPIO2_25 & GPIO2_28 are found shorted internally.

    We were using this pins. We removed all connections to this pin. And cleaned the PCB many times. But still they are shorted. So we think they are shorted internally. Any links with the problem?



    Thanks & Regards,
    Sajeevan.K
  • 0 in reply to SAJEEVAN K8
    Intellectual 330 points
    Hi,

    It is now very urgent for making it working. Because customer is coming in next week. We have already ordered for another AM572x EVM. But it will take one week to come.
    We have to do a lot of testings, before that.

    Can this problem card be replaced with another one, possibly from Bangalore office?

    Thanks & Regards,
    Sajeevan.K
  • 0 in reply to SAJEEVAN K8
    TI__Guru**** 393215 points
    Hi,

    Sorry, but we cannot resolve requests for replacement over the forum. You have to contact your vendor and resolve with them.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru 63385 points

    It sounds like something with respect to your usage of these signals created an Electrical Over-stress (EOS) event to the processor and damaged these pins.

    What revision of the board do you have?

    Did it include a power supply and are you using it?

    If not, are you using a power supply that meets all the requirements defined in the Hardware Users Guide?

    It is very important you only use a power supply that has an output isolated from earth ground. If not, you must never connect or disconnect the DC plug of the power supply while power is applied. In this case you should always keep the DC plug connected to the EVM and connect or disconnect the AC source, and you should bond the EVM ground and every external circuit connected to the EVM to a common earth ground.

    Here is an example of what can happen. You connect some of the processor pins to other circuits that are referenced to another ground or earth ground. This could be as simple as connecting a scope probe to a signal. However, you do not bond the EVM ground to the same ground as the other circuits before hot plugging the DC plug. The construction of the DC plug allows the positive terminal to make connection before the negative. If the power supply output is not isolated, the entire EVM rises to 12 volts relative to earth ground because the power supply ground is not connected yet. When this occurs the processor pins connected to external circuits may see a negative 12 volt potential relative to the EVM ground. This is very likely going to damage the processor pins. I realize the period of time where the positive terminal of the DC plug is attached while the negative not attached is fairly short, but it is more than long enough to create EOS event to the processor.

    Regards,
    Paul

  • 0 in reply to peaves
    Intellectual 330 points

    Hi Paul,

    Thank You for the explanation.

    First let me answer Your questions.

    What revision of the board do you have?

    A: A3A

    Did it include a power supply and are you using it?

    A:Yes. It includes an AC Adapter. And we were using the same.

    We were using 2 pin AC connector(this is also received from TI) attached to the AC Adapter.

    Power source is 230 V AC 50Hz.(2 pins means only Phase and Neutral is connected)

    It is very important you only use a power supply that has an output isolated from earth ground.

    A: We were using the same AC Adapter provided from TI,  its output might have isolated from Earth?

    Actually I was not using oscilloscope. I was using only multimeter to check the voltage level at the output pins. Whether it is switched on on or not.

    It is true that Ground terminal of Multimeter and EVM are not connected permanently. Whenever measuring it will be connected. After measuring it will be removed.

    Also it is true that I was connecting and disconnecting DC plug only, not AC connector.

    The external circuit we were using is only a general purpose PCB. (This PCB contains 3 LEDs with transistor switches, One Push button and one RS485 transceiver only).

    And this PCB was not connected to any other Circuits or systems.

    The Power supply(+5V) and GND for this PCB were taken from EVM only.

    When I was not getting the desired output at port pins, I have cut these +5 and GND connections between EVM and PCB(first  +5V and then GND).

    I am giving these details, to know exactly, what actions from me caused the failure of card, so that I can avoid this in future.

    I think here Power supply output is isolated from earth(since we were using the same TI AC Adapter)

    Based on these inputs, please give a more clear explanation. We are eager to know what went wrong.

    Also can we sent back the card to TI Bangalore office, so that it can be repaired or replaced from there. (Only Processor card).

    Expecting your further support,

    Thanks & Regards,

    Sajeevan.K

  • 0 in reply to SAJEEVAN K8
    TI__Guru 63385 points
    Thanks for providing a detailed description of your usage.

    I want to confirm a few things. Was the other side of the RS485 transceiver connected to any external devices? Which processor pins were damaged and were they connected to any of these external circuits? If so, which external circuits? For example, was the damaged pin connected to the push button? If so, were you using a shielded push button with the shield connected to ground?

    Provide more details of how you were powering the circuits on the external PCB from the EVM 5 volts. Can you provide a schematic of this board?

    I cannot say for certain what casued this to happen, but it may help us understand what happened if you provide a schematic of the attached PCB. Were you operating the EVM and attached PCB at a certified and test ESD workstation? Were you wearing a wrist strap at all times? This processor is constructed using circuits with very small geometries. Therefore, you need to be very careful when handling these devices because the very small circuits in the processor can be damaged by static charge that accumulates on your body or clothing.

    I’m not familiar with the return/repair process, but fairly sure it cannot be repaired in the TI Bangalore office. You will need to discuss this topic with your local distributor or TI representative.

    Regards,
    Paul
  • 0 in reply to peaves
    Intellectual 330 points

    Hi Peaves,

    Sorry for the long delay in giving a reply.

    I got a new AM572x EVM, and busy in completing the work, before the customer arrives.

    Let me answer the questions.

    1) Was the other side of the RS485 transceiver connected to any external devices?

    No

    2) Which processor pins were damaged and were they connected to any of these external circuits?

    GPIO2_28 and GPIO2_23 were found to be shorted, even after removing all the connections

    GPIO2_28 was connected to a Push Button.

    Push Button is connected with a 10K resistor.

    One end of resistor was connected to +5 Volts, other end to one end of PB. Other end of PB connected to GND.

    The junction of PB and resistor connected to the port pin GPIO2_28.

    3) was the damaged pin connected to the push button?

    Yes

    4) If so, were you using a shielded push button with the shield connected to ground?

    One terminal(let us call 1st terminal) of the PB connected to Ground, other terminal(let us call 2nd terminal) to 10k resistor.

    2nd terminal is also connected to GPIO2_28.

    The PB, we were using was not shielded PB.

    I think by mistake we connected +5V for PB operation. It should have been 3.3V. Continuous application 5V to the port pin may be the reason

    We would be more careful in future.

    Please extend Your support.

    Thanks & Regards,

    Sajeevan.K