I am fairly new to Arduino hardware and software. I am using a field effect water flow meter. If two Arduinos are powered from the same power can two Arduinos read the same sensor without issue or am I too simple minded to understand the issue?
Thanks
Somebody is probably due to come along with a better answer for you, but just a suggestion, you could have one Arduino read the sensor, and have that Arduino output the data to the other. That way, both can use the data. I understand this probably isn't the most efficient way, but something to play with whilst waiting for somebody more experienced.
What kind of sensor? Analog? SPI? I2C? One Wire? Something else?
You can isolate the two by using an OP AMP Voltage Follower (LT-1215) . This is an impedance matching circuit with effectively infinate input impedance and 50 ohm output impedance. The second arduino would not know it was getting a copy of the signal and not the original signal because of the characteristics of this configuration.
LT1215.pdf (339 KB)
Marshiewoo:
Somebody is probably due to come along with a better answer for you, but just a suggestion, you could have one Arduino read the sensor, and have that Arduino output the data to the other. That way, both can use the data. I understand this probably isn't the most efficient way, but something to play with whilst waiting for somebody more experienced.
It could be a long wait.........
I submit that having one Arduino pass data to another would not only be the most painless and least wasteful way of doing this, but might actually have some value, and the waiting time would be better devoted to better researching, and explaining, why you would need two Arduinos in the first place. The only instance I can think of is where the first reads a sensor and passes data to the second, which acts as a display repeater. This is more or less what Marshiewoo is saying, but it means that the two Arduinos serve different purposes and can be of different types - and cost.
My sensor stuff is all on a Mega running on wall power but, I while am developing the remote on a Uno, I think a Teensy or something, on batteries, would suffice.
allen13331:
I am fairly new to Arduino hardware and software. I am using a field effect water flow meter. If two Arduinos are powered from the same power can two Arduinos read the same sensor without issue or am I too simple minded to understand the issue?
Probably, depending non the signal output strength of the field effect water flow meter.
If the sensor produces purely voltage eg 0v off 3v half flow 5v full flow etc... then yes
If the sensor has 2 or more pins, have both arduinos flag a single pin high... then check the status of the pin before attempting to read the sensor?
Marshiewoo:
Somebody is probably due to come along with a better answer for you, but just a suggestion, you could have one Arduino read the sensor, and have that Arduino output the data to the other.
Why wait for another answer when this is a great and easy solution, if not the best.
As I understand it, field effect water flow meters use pulses as output. The greater the flow, the faster the pulses.
I expect you can read the sensor with more than one Arduino. As a bonus, if you need pull-up or pull-down resistors to bias the input, you'll only need one.
You are correct the water sensor uses a pulsed output so there is only one sensor pin used. The trouble I have is that I have one pin free. I am using a touch screen shield for the Arduino to display the results of several sensors. I have to use the Arduino Uno to match another display which is mounted in a wall.
The project monitors 18 temperature sensors, two water flow sensors, 5 tank depth sensors ( reading 5 275 gallon totes) and a probe sensor to control a pump to irrigate the yard when the 5 totes fill to capacity (1500 gallons). I have two geothermal heat pumps that are open loop. The water from the geothermal is captured in the tanks. I want to monitor all aspects of the heat pump, hense the abundance of sensors.
Many will say this project is overkill and I should set the sensors up differently but this how I am learning the Arduino AND getting some useful data.
I could see no reason why two Arduinos could not measure the same pulsed voltage output as long as everything was powered by the same supply. But just to make sure I thought I would run it past this group. Worst case is I fry a couple Ardunios or get funny readings. When I hit 60 I decided to try to teach myself and C and learn the Arduino. I must say it is fun, but a little frustrating at times.
Thanks for all the ideas.
I would consider having the sensor drive two Optical Isolators such as a PC817 with their internal LEDs in series. Then separate isolated output to each arduino.
See datasheet etc. HERE:
A Mega should handle that, and you are likely to need one for the memory eventually anyway.
It seems that touchscreens typically confine themselves mainly to pins 22-52, and I can only see eight pins for the rest, as you can put the temp sensors on a one-wire bus.
I would second the suggestion to use separate optos given in Reply#10 just on general principles. It is SOP in engineering design to provide isolation between devices (or SLAVES) receiving or sending information to MASTERS.