I have an arduino with a nokia 5110. I connected it with no resistors except for the backlight and there is no level shifter.
Any idea why the nokia will not work on battery power but works on the usb power.
I have fully charged two lipos 3.7V, 500mah and 1200 mah. in series at vin and ground. Nokia not work.
Any ideas? Again it works perfectly fine from the usb.
I think the battery p
It works when i use my lipo battery pack but because the battery pack is designed for phone i have to plug the phone into battery as well. A side question. Can i use the arduino serial to send what the phone is communicating to keep the battery from turning off?
sb07:
I have an arduino with a nokia 5110. I connected it with no resistors except for the backlight and there is no level shifter.
Any idea why the nokia will not work on battery power but works on the usb power.
I have fully charged two lipos 3.7V, 500mah and 1200 mah. in series at vin and ground. Nokia not work.
Possibly just slack wiring. 7.2v should be enough but maybe the batteries aren't delivering like you think they are, particularly the 500 mah, and Arduinos aren't that frugal with power. By far the biggest power hog would be the backlight and and the display probably runs on virtually nothing. You may find that it will spring to life if you disconnect the backlight. Another thing you may find is that it works perfectly well without a backlight anyway, just like it did in a Nokia 5110 phone. This is particularly the case if you have a display with cool blue LEDS, about which there is nothing cool at all.
I run mine off 3.3v and no level shifting for the signal pins.
sb07:
the 2 lipos in series give 8.4 volts.
I tried a 9 volt battery doing 8.2 Volts
Were those voltages measured under load, or no load?
I plugged it back into the usb and the screen is able to display.
I submit this proves there is nothing with Arduino, the display or the code, and it also proves that there is everything wrong with the battery and/or its connection to Arduino. Most Arduinos have a power LED. You might start by checking that. If you can't see it, I guess that means this thread has the wrong title.
Bear in mind that on a USB connection the Arduino supply is typically 4.6V and when driving via Vin is 5V, this small difference is probably upsetting your display.
Connect with series protection resistors in the data lines and power the LCD from 3.3V:
Very likely. It's pretty clear that resistors in the data lines can't do any harm, but their presence or absence can hardly be a game changer. I have had one 5110 running more or less continuously for about four years, no resistors and no problem.
Nick_Pyner:
Very likely. It's pretty clear that resistors in the data lines can't do any harm, but their presence or absence can hardly be a game changer. I have had one 5110 running more or less continuously for about four years, no resistors and no problem.
The resistors are important if you wish to keep within the specified data sheet limits for the PCD8544. This driver chip is NOT designed to be 5V logic level tolerant when it is powered from 3.3V, it just happens to tolerate this overdrive quite often so users believe this is OK.
The resistors limit the current into the parasitic diodes built into the driver inputs, these currents end up pumping up (modulating) the 3.3V rail and upsetting the chip operation. The PCD8544 input pins are pretty tolerant to this abuse but it is a bit of a lottery whether it work correctly under these conditions.
Ideally proper level converters would be used, but the 10K limits the pin input currents whilst still letting the logic levels to be established.
