Nano stops running and flashes the power LED rapidly...

Projects General Guidance
1

I have searched and searched with no real luck finding out what this means.
The project is a solar or mains powered six battery maintainer that will eventually live at our hunting cabin to maintain the toys up there. Given, this thing exploded from a simple maintainer to an automated 4 stage lead acid battery charger. I may have hit the limits of the nano as there is an i2c RTC, DHT11 temp sensor, an 8 relay bank on a 595 shift register and a 4x40 LCD on a 595. On startup, everything inits fine, and even runs for a few days. eventually I'll come home from work to find the display blank (Vee is run by a PWM'd charge pump), D13 off(its normally on), and the power LED blinking rapidly. It will not respond to a reset push either. But, cycling power brings it right back.
I think I may have a RAM usage issue but I'm not for sure. I know if create large strings or character arrays it can cause issues but I'm sending the initial screen setup directly i.e.
lcd.printIn("this is the first line on the screen!!!!")
not
String lineone = "this is the first line on the screen!!!!"
lcd.printIn(lineone)

Does this direct format still use up or fragment the RAM?

Ironically, I see this happens when people are adding things, in this case, I had removed all of the serial data I was sending to a processing sketch and left it all on the LCD to speed things up. Has anyone else seen anything like this?

Thanks in advance!

2

Hi,
The powerled flashing is strange. If the nano is built like the original design, the led (+resistor) should be connected to +5v and GND only. Even if you would use too much RAM it shouldn't effect the powerled.

Blinking rapidly could indicate a problem with your power-supply. It would also explain the blanked display, since not only the led, but the controller of your Nano is turned off/on every time the led blinks.

Could you post your complete code (using the #-button) and a schematic of your project ?

3

Papagolf:
I think I may have a RAM usage issue but I'm not for sure. I know if create large strings or character arrays it can cause issues but I'm sending the initial screen setup directly i.e.
lcd.printIn("this is the first line on the screen!!!!")G
not
String lineone = "this is the first line on the screen!!!!"
lcd.printIn(lineone)

Does this direct format still use up or fragment the RAM?

Use the F() macro to store your string constants in flash:

lcd.print(F("this is the first line on the screen!!!!"));

You may have a power issue or one of your variables could be overflowing.

4

Coding can have no effect on the power LED, so there has to be a power problem at the root of this symptom. How are you powering the nano?