LPC43xx killed on ISP conection

[javiervallori]

Hi,

I am having a problem with a product developed with the LPC4337 uC. We make the USB conexion for ISP operations through a PIN header. Sometimes, after proceed to connect the USB in the PIN header, the uC dies, and can't be recovered. After that, no clock signal exists, and it is not possible to entry in boot loader pulling down the ISP pin, and making a reset. The uC is simply death.

Any suggestion? Is the pin connexion order so critical that can crash the uC?

Thank you.

[javiervallori]

Hi Jeremy,

I proceed to send the files to your private email.

[jeremyzhou]

Hi Javier Vallori,

Thanks for your reply.
Please check the email, I've replied the schematic with two sticky notes for a bit adaptation about the hardware circuit.
In addition, I'd like to know whether this issue happens when you force the MCU to enter UART ISP mode.

Have a great day,
TIC

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[javiervallori]

Hi Jeremy,

About the second question, the issues seems to happen in the moment of the conection. After connect a funcional device, I tried to load the boot_lpcscrypt with the lpcscript tool, I get a "nothing to boot" answer, and then the device does not work longer anymore.

We will proceed to try the suggestions you mention in the sticky notes. But also I want to indicate that the datasheet tells that no external resistor on USB0 pins should be installed (please see bellow):

Apart, about the change from 5V to 3.3V, in the demoboard, the USB protection is connected to a Vbus pin (that means a 5V pin) as is shown in the following picture (please see the red marked line):

Anyway, we will proceed to test your suggestion, and report to you the result.

This issues happens just in a few of devices, maybe around 5% we program.

Thank you

[jeremyzhou]

Hi Javier Vallori,

Thanks for your reply.
After the double check, I think it's not necessary to do some hardware modification.
I was wondering if you had tried to force the MCU to enter USB ISP mode, then open the Flash Magic tool to connect the MCU, in the Flash Magic, it integrates a erase all flash function which is able to recover the MCU.
You can learn how to use the Flash Magic by refer to the post.
https://learn.adafruit.com/getting-started-with-the-lpc810/programming-the-lpc810-with-flash-magic

Have a great day,
TIC

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[javiervallori]

Hi Jeremy,

We "hacked" our own product changing the boot ISP pins, setting up the uC to boot with UART insteat of USB, and to try to erase with the flahmagic tool as you suggested. We didn't get success  results. The uC seems to be broken.

Anyway, finally we have decided to redesign the product and change the ISP boot interface from USB to UART, because we have found another barrier with the ISP boot USB mode. Seemingly, the ISP boot USB mode is disable if the CRP is enable. Unforntunetly we realize in our product, and we confirm it here:

https://community.nxp.com/thread/419893 

I agree with the guy of the linked post, that it would be appreciated an update in the documentatión explaining it.

Anyway, thank you for your support. If you are still interested in the "brick" uC to examine it I could send you by post.

Best regards

[javiervallori]

Hi Jeremey,

thank you for your support.

The following picture shows the box "adaptor" from USB to target PIN header. It is just a cable conversor with some push buttons that allows reset and push ISP pin down operations manualy.

On the target board, the following PIN header is mounted:

And the schematics of this connector is the following:

The target board, has got a 3.3V regulator powered from the 5V provided from the USB. This 3.3V powers the uC. Apart, the ISP and RST lines have got an external weak Pullup in the target board.

This phenomenon does not always happens. But when it happens, the uC dies, and until now, in all cases the Xtal does not oscillate, and in some cases besides the ISP pin are pulled down from the uC.

I guess it could be something with the pin connection order. The USB connector's shape garantees a fix connection order. But a PIN header don't. But it is just a supposition.

I can send you a schematic of the hole board, but I have to do it through a private way. The company does not allow me to publish in a public forum. As well,  if you desire, I can send you one board with a crashed uC.

Best regards.

[jeremyzhou]

Hi Javier Vallori,

Thanks for your reply.
Please check my message and send the schematics of the box "adaptor" and board to my private email.
Whether the MCU is not able to be recovered after becoming 'brick'.

Have a great day,
TIC

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[jeremyzhou]

Hi Javier Vallori,

Thank you for your interest in NXP Semiconductor products and
for the opportunity to serve you.
Whether you can share some pictures of the board you use, in further, please introduce the processes which can replicate this phenomenon, as I've not encountered this phenomenon before.

Have a great day,
TIC

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