I am experiencing a strange serial issue, both a lcd screen and bluetooth module are failing to work with a power adapter. The lcd lights up and the bluetooth powers up, but serial communication to them does not work. If I have the arduino connected via usb everything is working fine.
The weird part is if I click the reset button after hooking up the power, everything functions correctly. It is my understanding that when hooking up with usb, reset is automatically set. Is there a way to manually call reset via code? I have thought about a digital write from a pin to the reset pin, but that would infinity reset the board.
Any insight and suggestions would be highly appreciated!
If you are saying that if it running fine off usb and you unplug the usb and then plug in the wall-wart in dc ext pwr the barrel jack.
That the program does not run ?
Let's walk throught this step by step. Initial conditions
Everything working fine off USB. CONDITION CHANGE
Power removed from uC as USB is unplugged. CONDITION CHANGE
External power applied to ext pwr jack OBSERVATIONS
uController does not seem to start running code .(nothing happens) CONCLUSIONS
You need a Power-On Reset circuit to initiate a reset upon application of power to external pwr jack.
raschemmel:
If you are saying that if it running fine off usb and you unplug the usb and then plug in the wall-wart in dc ext pwr the barrel jack.
That the program does not run ?
Let's walk throught this step by step. Initial conditions
Everything working fine off USB. CONDITION CHANGE
Power removed from uC as USB is unplugged. CONDITION CHANGE
External power applied to ext pwr jack OBSERVATIONS
uController does not seem to start running code .(nothing happens) CONCLUSIONS
You need a Power-On Reset circuit to initiate a reset upon application of power to external pwr jack.
Thanks for the quick reply. It looks like your links are dead or the pdfs did not upload?
To further clarify the program does run, just the lcd and bluetooth fail to work correctly off of power. I'm assuming this is because they are both serial communication. If I click the reset button on the arduino the bluetooth and lcd will work off of power.
Do you have anything connected to either pins 0 or 1 (Rx & Tx)? This would usually give the reverse of your problem, though ....OK through the power jack but not working correctly via USB.