topic Re: lpc2388 sometimes not starting my code in LPC Microcontrollers

lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:03 GMT

Content originally posted in LPCWare by m2babaey on Tue Jun 18 22:04:45 MST 2013

Hi
I am testing an LED blink program on LPC2388
The problem is that sometimes that I connect the power it works, and sometimes it doesn't work, why?

I have a pull up resistor on P2.10
I also searched the net and found a similar problem here (https://rowley.zendesk.com/entries/61610-Application-not-starting-up-from-reset-LPC2000-) but I am using Keil and I don't know how to define startup_from _reset in keil

Any help would be extremely appreciated

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:04 GMT

Content originally posted in LPCWare by mburton on Wed Jun 19 00:00:33 MST 2013

Hi,

I don't know what hardware you are using or anything about your program but I have found that a common cause for MCUs not starting correctly on power up is because the MCU doesn't come out of reset correctly. I now use a supervisor chip (MCP130) to drive the reset signal and no longer have any problems with MCUs not starting on power up.

Cheers,

Mark

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:04 GMT

Content originally posted in LPCWare by m2babaey on Wed Jun 19 01:12:20 MST 2013

Yes,

This is a reset related problem

I used a lower resistor for reset pin and The application starts working almost each time I connect the power

But when I apply a low to the reset pin, it stops working and after I remove the low state, it doesn't start up again

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:05 GMT

Content originally posted in LPCWare by farid69 on Tue Jul 02 00:21:47 MST 2013

INDISPUTABLE you have not any problem in software .your PCB is very elementary and you have a big noise on cpu. place 100n multilayer cap front of each vcc_3.3v pins and premier fron of 1.8v cpu vcc (NC pins) .Also your PCB is very important and you cannot take answer from lpc on Air and breadboard and etc.

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:05 GMT

Content originally posted in LPCWare by m2babaey on Tue Jul 02 00:34:52 MST 2013

Thanks

yes, I looked at my VCC on oscilloscope and there was a big ripple on 3.3V (over 500mV)

I added a 330uF capacitor at output of LF33 and my circuit now works fine with 39K and 100nF on reset pin when power is connected

But when I apply a low to the reset pin to reset the chip, it dosn't restart

Maybe it's entering ISP mode, but I have a 10K pull up on P2.10 and I don't know what else I should do for the chip to restart after hardware reset

This is interesting that if JTAG connected is connected, hardware reset works fine

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:06 GMT

Content originally posted in LPCWare by m2babaey on Tue Jul 02 00:40:51 MST 2013

I have 100nF caps on VCC pins but not NC pins( 21 ,81,98 in 2388)

Really they should have 100nF capacitors?

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:07 GMT

Content originally posted in LPCWare by farid69 on Tue Jul 02 01:45:39 MST 2013

NC pins have a little riple that directely connected to cpu . for usb safe interface and other high speed application 3 cap low cost guarnaty your work.

Re: lpc2388 sometimes not starting my code

lpcware — Wed, 15 Jun 2016 19:51:07 GMT

Content originally posted in LPCWare by farid69 on Tue Jul 02 22:05:26 MST 2013

10k pull up on p2.10 is true but if lpc entering ISP mode , your program don't working because the ISP mode programing flash and lpc in this time stoped.

search RSTOUT voltage pin . if it's about (3v) lpc is working but if therewith reset lpc , this pin yet is 3v you have a problem in reset circuit.

what is your JTAG circuit? I take a high speed and true circuit for JTAG and lpc connect.