Locked out from LPC5536?

[orange_chris]

Hello,

due to a silly typo, I have accidentally configured PIO0_0 as a GPIO and thus disabled SDW on that pin and can't connect to the MCU any more.

My question is:
From what I am used to from other MCUs, the pin configuration should be reset when the RESET pin is pulled low and that I get the SWD running again if I select "Connect during reset" in IAR Embedded Workbench. Is this different with LPC55xx MCUs? Is there a known way to get back in and erase the MCU?

Regards,
Christian

[xiangjun_rong]

Hi,

Your application code has configured the PIO0_0 as GPIO, which should have been SWCLK pin, so you can not download/debug again with tools.

I do not know if your PCB board supports ISP mode?

If your PCB board supports ISP mode, you can enter ISP mode, then erase all flash, it is okay.

After you enter ISP mode and use uart0 as communication port.

1)blhost -p comX get-property 1

check if you can communicate with the LPC5536

2)blhost -p comX flash-erase-all

then you can use SWD to download with tools

Hope it can help you

BR

XiangJun rong

[orange_chris]

Fortunately, I was able to solder a wire to the pin and pull it low to enter an different boot mode that does not execute from flash and re-connect.
The question remains is if it is possible to connect to the SWJ-DP/ITM with the reset held low all the time. This would also inhibit the execution from flash (or somewhere else)

[xiangjun_rong]

Hi,

For the LPC5536, in order to enter ISP mode, you have to connect PIO0_7 to a pull-down resistor, connect PIO0_5 to a pull-up resistor, so the PIO0_7 will be low, PIO0_5 will be high after Reset, the LPC5536 will enter ISP mode, you can use blhost instruction to erase all flash.

Pls refer to section 26.2 Functional description  in LPC553xRM.pdf

BTW, there is not SWJ-DP/ITM pin for LPC5536, I suppose you refer to the other ARM family.

Hope it can help you

BR

XiangJun Rong