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
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.
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.
I have 100nF caps on VCC pins but not NC pins( 21 ,81,98 in 2388)
Really they should have 100nF capacitors?
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
HI
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.
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
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