I have an Arduino ATMega2560 running a couple peristaltic pumps. Specifically, I send pins high to trigger a relays. The relays supply the pumps with 12volts power. I have 220ohm resistors on the low voltage pins to trigger the relays.
The problem I'm having is that my ATMega resets every time either pump starts. It kicks me back to my first switch case (resetting the system). When I unplug my 12v, 5amp power supply, the code works perfectly. It only seems to happen when I try to supply the pumps with the voltgage/amperage required to power them (more than enough power for them). My arduino is actually isolated on it's own 5V, 2amp power supply.
Any suggestions for me to try will be greatly appreciated.
fyi - I think I'm going to have to dig a bit deeper than RF noise. I leaning more towards a power issue drawing the system down or tripping a reset. Please help!...if you have suggestions. Thanks for taking the time to read this.
Do you have snubber circuits across the relay contacts? Do the relay coils have flyback diodes?
Pieter
I'm using one of these micro controller friendly relay system from SainSmart:
Hi, You need to work to understand that relay board. It has optical isolation that you should be using..
DISCLAIMER: Mentioning stuff from my own shop...
See the information and schematic ON THIS PAGE
follow that to Arduino Power here: http://arduino-info.wikispaces.com/ArduinoPower
You need to consider grounding and how your system is wired...
Also suggest you read this: http://arduino-info.wikispaces.com/Arduino-Project-Planning-Electrical
Let us know what you figure out...
Hi, I am using the optoisolation capabilities of the relay. Does this snubber/flyback diode still apply to the optoisolated system?
I'm reading about it now to learn more about it. From what I understand, both the motor and the relay have potentials for high voltage spikes when their electrical path is suddenly open (open circuit).
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Can you please post a picture of your project, so we can see your component layout.
Thanks.. Tom.. 
Sure - let me sketch it and i will post in a bit
*Note...this is an H-bridge circuit so that I can run the pump in either direction
Still searching for an answer to my post here...
Just Below my last message is a downloadable attachment of my circuit (hand drawn picture).
Hi,
Do you have a picture of your project?
OPs pic.
Tom...
Hi,
Can you fit a diode in place indicated on the diagram. Anode is to Negative and Cathode to Positive.
This is to suppress any back emf that may arc across the relay contacts as they open.
1N4001 or up to 1N4007 type will do.
Tom....
UsernameD:
Still searching for an answer to my post here...
Just Below my last message is a downloadable attachment of my circuit (hand drawn picture).
You have to be patient, you do not necessarily know from what parts of the world we are located.
I am in Australia, local time 22:53, your local time from your details says 14:53.
It is also a week day and quite a proportion of forum members have occupations.
So as the world turns, you should get more replies.
Tom...
HAHA...I'm aware Tom,though I admit, I'm very antsy about this. This is a work thing for me. My company took a gamble on a coder (me) to make a prototype instead of doing it the old fashion way of using 1000 hardware pieces. I have until tonight to figure this out....then....the hardware guy gets to laugh in my face and say "see...this is why I like doing it the old fashion way"
I will try the diode as you show here. Thanks for posting the actual diagram.
So...it seems that I didn't have my 12vDC for the motors completely isolated from my controller. Now that I have fixed the issue (had the ground still sharing - the one that is in line with the inputs on the relay) I am now able to run the motor completely in one direction.
HOWEVER!....Running the motor in reverse, (by activating the reversal relay on the relay board which in turn switches my DTDP relay) now has a similar issue in that it runs a few seconds...then messes up and sends me right back to the beginning of my code again.
So...1/2 of the problems gone, just have to figure out the motor in reverse problem. BTW...I removed all other timer/communication devices from the system except for my Serial Monitor abilities.
Hi,
Do you stop the motor before reversing?
Have you fitted the diode?
Have you kept ALL the 12V motor wires and supply away from the controller and its wiring?
Tom..
