I have so many things to ask!
I m enthusiast with arduino and I'm not experienced!
I have read and watched dozen things about it. Does not seems difficult but requires some electrical knowledge. I have ordered my starter kit and I can't wait to start
My first project will be an electrical scale with gsm and temperature-humidity sensor + Nokia LCD screen + 2 button caps.
One button for screen activator and the other for a function that I want to implement.
The project must be standalone with batteries because it will placed to remote area for months (2-3) .
The good think is that I have plenty of space for any type of batteries (but I don't wish to be very weight) and all sensors will be activated 2 times per day.
First of all need to know if all parts can be connected together...Ξ have watched tutorial but most have LCD + 1 SENSOR
Secondly, how to choose power 5 or 3.3volts? Any criteria?
If I choose power 3.3V probably need AA rechargeable batteries 3v (2700mha) li-ion battery on parallel connection. I m confused because a gsm module that I have found works with 3.4v. How I can deal with that volt miss matching? What you suggest for power ?
Thirdβ¦
I m web programmer and flash 32 KB seems too small to me...The code will not be very complicated but requires some libraries. Any clue for my concern? Is OK?
DON'T parallel triple-AA NiMH 3.6V with single Lithium 3.6-ish Volts. They charge and discharge at incompatibly different rates so you are better off choosing one and sticking with it if possible.
Suppose that you used a single Lithium:
The gsm might say 3.4V, but read the specs sheet especially "absolute maximum ratings".
Connected to a lithium battery ( 3.7 Volts nominal ) one expects 3.2 to 4.2 Volts.
Many 3.4 or 3.3 V devices will be fine with that.
Even a badly coded or miswired recharge manager on a Lithium should never go outside -0.1 to 4.8 Volts
I don't know your LCD and I tend to use 5 Volt ones myself. Those are definitely ok with 4.2 to 5.4 Volts and i2c from a 5 Volt arduino nano 328. At least the ground must be common with arduino ground. I have not tried testing outside that range so I do not comment on your LCD.
I don't like the prospects of trying to get months of use. Batteries tend to run down much quicker than you would expect from only the arduino power usage due to internal leakage current, especially once they are a few years old. Choices are : power wires from Elsewhere such as the house, or researching and adding battery recharge management code; possibly using some additional components and spare voltage sense inputs of your arduino to monitor the battery voltage(s), monitor the light levels, and decide whether to allow recharge from a mains adapter or a silicon solar panel located at the nearest daylit place to your control system.
A possible option would be to have a common ground, a single 3.7V lithium and "1st priority" recharge circuit powering the 3.x Volt devices, and a 4xAA "5 Volt" "2nd priority" recharge circuit powering the type of LCD screen which I use, and any auxiliary 5 Volt devices such as an inspection light. About the only good news here is that a single small silicon photovoltaic panel, which may be rated at about "9 Volts 0.2 Amps" or thereabouts can, while recharge is desired, be safely dropped into either 3V or 5V battery sets without necessarily needing a converter. It does need sensible switching though, to only drop it to one battery set at a time and only while recharge is required. You might prefer to find mains to dc converters to use instead.
Remember to power down the hx711 in between readings as well - you need to do this independently of putting the Arduino to sleep. The library you are using has a power_down() and power_up() method.
First of all all my parts works around 3.3 Volts
GSM 3.4 ~ 4.4V
HX711 2.6 ~ 5.5V
LCD says...
Power supply voltage:2.7V-3.3V,5V is OK,but part of the screen becomes black when tested
Data interface level:2.7-5V
Backlight power supply voltage:highest 3.3V
Installation diameter:2mm
Backlight:White
Actually I don't need the light.
It will be outdours, so the only "external" real solution is the solar panel.
I have found li-ion batteries with 3.6v and 3.7v. What do you suggest? 3.7 I guess.