Hello, I am using LPC1768 and programming it using ISP. What i have observed is that the programs that i load work fine but when i repower the LPC board, the code starts to work only after a reset. The code executions should start after powerup. Kindly let me know what could be the possible issue.
Hello, to me it looks like a problem with the power supply. If you switch on the power, all the devices in your circuit draw current. If this ist too much and the voltage drops below a certain level, the controller might end up in an undefined state. Solution might be too change something on your power supply. Or maybe there is a parameter to delay the startup of your controller. I hope this will help you!
Guest
#1854376
Have you enabled the brown out detection? Another possibility is the power supply: If you only switch off the power for a few seconds there may be capacities in the circuit which holds the power on a sufficient level. As a result the µC doesn't recognize the power loss.
Are there any loops in the initialisation which wait for bits to be
set/cleared by the hardware (something like while
(!(SOME_REG&SOMEMASK)){;})? IF so, check with "LED-blink-debugging" if
the code "hangs" in such a loop. Did you try with the ISP interface
connected and disconnected. Did you check the VCC, BSL and RST levels
with a scope? Do you use code from NXP's CMSIS package to init the
clock-system? If not, you may at least do a few tests with the code from
the package.
Mk Bit wrote: > Hello, > > to me it looks like a problem with the power supply. > > If you switch on the power, all the devices in your circuit draw > current. If this ist too much and the voltage drops below a certain > level, the controller might end up in an undefined state. > > Solution might be too change something on your power supply. Or maybe > there is a parameter to delay the startup of your controller. > > I hope this will help you! Thanks for your response. Ya it looks like problem hardware only. I have herewith attached the circuit, It would be great if you check this circuit The reset and isp circuit i have uploaded to this link The RST# goes to controller pin 17.
Attached files:
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Reset_abd_ISP_circuit.JPG
(13 KB)
Guest
#1855416
Is R22 470 Ohms? Together with the 10k (R21) the Reset Voltage might be very low.
Martin Thomas wrote: > Are there any loops in the initialisation which wait for bits to be > set/cleared by the hardware (something like while > (!(SOME_REG&SOMEMASK)){;})? IF so, check with "LED-blink-debugging" if > the code "hangs" in such a loop. Did you try with the ISP interface > connected and disconnected. Did you check the VCC, BSL and RST levels > with a scope? Do you use code from NXP's CMSIS package to init the > clock-system? If not, you may at least do a few tests with the code from > the package. Thanks for your reply. There are no loops in the initialization. I have checked the VCC, BSL, RST lines BSL line: default -> 3.1v After ISP switch - 0 -> 3.1v (the value changes from low to high) Vcc line: Default -> 3.3 v After Reset - 3.3v RST line : Default -> 1.7v After Reset - 0 -> 1.7v (the value changes from low to high) RST out Line: Default -> 3.2v after reset - 0-> 3.2v (the value changes from low to high) These lines seems to be working fine, Any suggestions to the possible problem??
Guest
#3500734
helloo i have a challenge with lpc 1768 reset. in several case when i reset this processor via the reset pin and connect it directly to gnd the ic will crashed and burnes.so that for avoiding ic failing i should reset the ic reset pin via the resistance.