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Lighting an LED on the OM13085 LPCXpresso board

Question asked by John Whitmore on Sep 13, 2017
Latest reply on Sep 19, 2017 by John Whitmore

I'm trying to get started with the OM13085 LPCXpresso board but NXP don't half make it difficult. Firstly the board I received had a broken jumper. One pad had a dry joint and the other had simply ripped the solder pad off the PCB, still soldered to the jumper. The jumper's function is to disable the debugger, so basically the debugger can't be disabled. If the solder pad hadn't been ripped off the PCB it's be an easy fix.


So I can't disable the debugger, I contacted NXP about the issue of receiving a broken board and they responded that I could order another. So they send a faulty unit and I can just replace it by ordering myself another. NXP are not doing themselves any favours here.


So moving on. There is a card supplied with the board which points to the web site "Get Started" at would it surprise you to hear that that page is a 404 page not found. Cant' say as it shocked me at all. The actual correct address is /demoboard/OM13085 OK there's not much of a difference but I'm having to fill in all the blanks left by NXP.


Leaving that aside for the moment you want to do a very basic test and turn on a LED which is connected to Port 3. So you'll have to set the direction register for that port "FIO3DIR". Now we get into an SDK and there is none. If you go to download the lpcopen sdk [1] there is one for the LPCXpresso LPC1769 board but doesn't install in MCUXpresso. You just get an error message to say that this file is not supported by MCUXpresso.


So there is no development assistance here so lets try and turn on a LED from first principles. I'll attach a quick C source file but you wouldn't expect it to work would you? The reset address is undefined. It's assuming zero which is what I'd assume as well


/usr/local/mcuxpressoide-10.0.2_411/ide/tools/bin/../lib/gcc/arm-none-eabi/5.4.1/../../../../arm-none-eabi/bin/ld: warning: cannot find entry symbol ResetISR; defaulting to 00000000


So lets imagine that I'm not writing for an NXP development board but for a board which uses an LPC1788 MCU. There is no header file supplied by NXP, there are no SDK's to support the device.


Even if you buy an NXP dev board you'll still struggle to turn on a simple LED. Perhaps my code is wrong and I've missed a register. Perhaps the reset address is not actually zero, perhaps a lot of things but I'm going to have to wade through as much User Manual for the chip and create a linker script from first principles for a device as there is no SDK.


Am I simply missing a world of information, or am I looking at the wrong development environment and the wrong MCU?


[1] LPCOpen Software for LPC17XX|NXP

[2] LPCXpresso board for LPC1769 with CMSIS DAP probe|NXP 

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