good day everyone
i need to collect 9 separate analog values from my sensors with a logger, and i have 3 arduino uno now. how many values can i collect from 1 uno? should i proceed with my 3 unos, and buy 3 sd card shield, or use a mega? how many sensors can i connect to a mega? can i use 1 sd card shield only if mega is able to collect all 9 sensors?
help is very much appreciated, thank you in advance =)
Hi, welcome to the forum.
The Uno has only 6 analog inputs. A few others (Nano, Pro Mini) have 8.
When the I2C bus is used, the Arduino Uno has only 4 analog inputs.
Use an Arduino Mega 2560 board.
16 analog inputs
A good alternative is the Arduino Leonardo.
12 analog inputs
With the Uno, the Mega and the Leonardo, you can store all sensor data to a single SD shield of course. You just write the data to a file.
How fast do you collect data ? Not 1000 times a second I hope, that would be too much.
What about a mux ? It switches between a number of analog channels : Gammon Forum : Electronics : Microprocessors : 74HC4051 multiplexer / demultiplexer
Perhaps it might be possible to combine some sensors to a single analog input. If you have sensors that are not accurate, and can be turned off, or allow some kind of tric, perhaps a digital output could be used to switch the sensors.
oh thanks for the advice. i'm collecting once every minute or every 5 minutes, still have not decided on that yet. i need the separate values simultaneously for diffuse radiation measurement, cant have them combined. anyway thank you again for the prompt reply. =)
That is a simple task, I would use the Leonardo board.
The Leonardo board is the same size as the Uno, but it is harder to use. It switches the serial port on and off, and the reset circuit is not straightforward.
Which SD shield do you want to use ? The Uno, Leonardo or Mega are all 5V Arduino boards, and the SD itself is 3.3V. A good shield converts the 5V signals to 3.3V and vice versa.
Do you know the Adafruit data logging shield ? It has a real time clock, so you can timestamp the samples, and it comes with libraries. It is known to work with Uno and Leonardo, and the Mega 'R3' version.