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I have programmed an LPC1768 to be nearly always in deep power down mode. It is waken periodically by an RTC alarm
Since I did this, I cannot reprogram the processor using the programmer included in Keil's microcontroller development tool kit.
What is the solution ?
Best regards
Debugging is not possible in Power Down mode on LPC17xx because the chip turns off also the debug interface. Therefore also flashing is not possible.
A simple solution is to force the chip into bootloader mode at reset by holding EINT0 low while resetting the chip. Since chip will stay in bootloader mode the application which uses power down won't be executed and it will be possible to erase/reprogram flash.
Thanks for the EINT0 idea. As a matter of fact, I had included some code to run a loop when coming out of deep power down if a pin was 0V.It works, I can see it on scope. I also can enter debug mode. Just cannot reprogram the flash : I get : "SWD communication failure" and then "Flash download failed"
Have you forced the chip into bootloader mode and then tried to erase the flash?
No, The pin is connected to its neighbour VddIO. So it is quite difficult to cut the connection temporarily. It is nearly as difficult as changing the micro.
Pb solved. After disoldering the NMI pin to add a pull up to Vdd and force it to Gnd at reset, I have been able to reprogram the uc.
Thanks for your help