This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC3220S: CC3220S stuck and always in Bootloader mode

Part Number: CC3220S
Other Parts Discussed in Thread: UNIFLASH

Hi Team,

I am facing one strange issue in CC3220S. Device was running and suddenly it went in unknown state and from where we were not getting any log. Checked power and CC3220S reset both are fine and Ic is out of reset.

But it looks like it is in bootloader mode and at SOP2 it has 2.52V, CC3220S is getting powered up with 2.8V power.

SOP2 is by default pull down with 2.7K resistor. 

I am able to program the board but without connecting SOP2 externally with Hig. After reprogramming also device is not coming out of that state and still this issue is there.

I am not able to do anything. This happened in two devices and both are still in that state.

Please guide us immediately on this as those devices are in field.  

  • Hi Sumit,

    Please provide schematic around SOP pins. What is your normal operation SOP mode and what is you Uniflash programming mode? Can you provide voltage levels at SOP2 pin after reset (by oscilloscope from reset to 2sec after reset).

    If you are sure that your device is not held at reset state and you are sure that is SOP2 pin not hold at high by external device, there is not much options than your SOP pin is damaged. It looks like damaged protection diode inside pin.

    Jan

  • Hi Jan

    Please find below image for SOP schematic. In normal operation mode, SOP2 is pull down with 2.7K and during programming using UART mode SOP2 is connected to VCC_2V8 after power up the device.

    Voltage levels at SOP2 pin after reset, that is the same thing, which i am doing right now.  Yes, Wi-Fi is not held at reset confirmed by measuring voltage level at reset pin and also if it will be in reset mode then it won't get programmed which is getting done even without connecting SOP2 with VCC_2V8.

    As you said damaged protection diode inside pin, how can we ensure this? And that is the reason to get device into bootloader mode? 

  • Hi,

    At your schematic is missing limiting 270ohm to Vcc. This resistor is part of reference design. Without this resistor will be i/o pin SOP2 much more stressed. I am not sure if this can cause damage of this pin. Please wait for additional opinion from TI.

    Please capture waveform by oscilloscope at SOP2 pin after reset. This can give us additional hints.

    Some additional information how should SOP2 behove you find here.

    Hard to say if your SOP2 is damaged or not. It can be many ways how to damage i/o pin internal structures (protection diodes or internal transistors). For example: ESD or over current via pin. From this reason is important here 270ohm resistor. Let say you have connected SOP2 pin directly to Vcc but there is missing Vcc for QFN chip itself. This will cause unlimited current via pin and internal ESD protection diode will be "toasted" instantly.

    Jan

  • Hey Sumit,

    Any updates on this?

    BR,

    Seong

  • Hi Seong,

    we found that SOP2 Pin was not directly short with ground but it had low impedance with respect to ground and that was around 100~200E. So might be Pin was damaged and i replaced with new IC and then it was working fine.

    I think that will be due to inrush current might be which explained earlier by Jan. 

  • Sumit,

    Thank you for the update. I'll be closing this thread. Pleae start a new one for any other queries.

    BR,

    Seong