Stability of connection, w850io, static IP

Hi, we have problem with connection stability with modules based on w5500. Tested many modules, the same problem occurs.

  1. the device is very sensitive to any EMI ESD
    will loose settings after relay or something else make noise. Then needs reset.

Questions are -

it is possible set or burn permanent static address to the chip? (when chip resets self will still have the needed address not Can not be used DHCP because of long lease period.
We can check for this data loss problem in code and after any similar failure occurs, we
reset and set up the chip again. This can happen often or after longer period of time.
How this can affect the lifespan of the module? Doesn’t matter how often the chip is reset?

How this behavior can affect the switch or router?

The problem with EMI is similar to W5500 Down/Lose Connection after some hours/days


  1. the device freezes after some time. Sometime is minutes and sometimes are hours.
    This behavior describe many people on web, but I didnt found any solution.
    My solution is, every 5 minutes reset chip by code and then the system works without freezing problem. This overwight to my first question about lifespan of module when continously is resetted.

We need to use the w850io modules because its dimensions.
Is original wiznet not the chinese clone. We will shield against EMI the cables and module as well, this maybe helps a bit.

All this occures in any shield or module we have with 5100 or 5500 chips. Only ethernet 2 module (green) from arduino does not reset by EMI. ( you can give him as close as possible to Relays and nothing, well made, but is big). But also hangs up after some undefined time of running code.

Thank you for any help.

From this clue, I think the main problem is not the module designer/maker, but the chip itself.

The hardware design document from official wiznet website explains about EMI spec, but I think this EMI is about the chip suffering from being broken/burned. So, we also need to know how can this chip suffer from being reset caused by EMI. As I know from testing in my posting you cited above, this chip is not as strong as STM32 of being reset.

To reduce the reset rate caused by EMI or other external noise, I cut the reset pin of the module. So, I do not use reset pin anymore. Only use software reset from code.

But, reset problem still comes sometimes although less often.

Did you use scope to see what happens to power at the W5500 power pins?

Then the issue is either the module, or your setup. Do not blame module until you verify your setup. Please provide pictures of the related devices, circuit diagrams of the relay connection and w850io module connection.

To find a solution someone must take responsibility and systematically troubleshoot the problem. Did you see people using scope or showing W5500 diagnostic outputs?

This may not help if the issue is the power quality.

Shield 2 is having onboard 5V → 3.3V regulator, with 47uF cap and quite a number of decopling caps. W850io module relies on external 3.3V, with 10uF cap at input and relatively small number of ceramic decoupling capacitors.

If your relay operation causes external 3.3V go below 2.97V (as per datasheet) then you are not guaranteed correct operation of the chip.

If you really want to make some troubleshooting, do the following: design small board containing regulator and needed caps as in Shield 2 (IC2/C5/C8) powered by 5V, and connect w850io through it to see the difference. Will relay cause malfunction?

Hello, thank you for all the ideas how to. I think, the whole problem is the extreme sensitivity of the chip itself. For example W5500 will reset after ESD spark from hand to table about 70cm+ far from any electronic an module 5500. No other device did react to this, just this chip. But as we can see in shield 2, there exists a way how to create relative durable pcb design on bigger board. As Eugeny wrote, we can try the setup with caps. The source is strong enough, but the 3.3V regulator, maybe can go under chip limit and the chip will restart, but I do not think this is problem.

The STM32 chips are good, but our design is based on ATMEL 128A.

Gentlemen, what is your opinion about SW or HW reseting and life span of the w5500 chip.
Does resetting touch this chip life span (its memory) in any way?

I do not think so. You can safely reset using hardware (reset pin) or software (MR register). The only issue here is that you can not operate the chip while you reset or set it up.

I mean STM32 compared to W5500 for the reset rate caused by EMI, STM32 is stronger than W5500. I think other microcontroller chips also have strong stability through EMI reset.

Thank you. Yes this is true. The W5500 is very sensitive to EMI. People are using this chip as well in important solutions. By my opinion is good chip, but needs quality shielding, high quality shielded cables and software, that can fast fix any fail.

The easiest way in our device will be catching the EMI freezing and then fast reset as possible with needed settings. Thank you.

ia there any solution for this problem ?
Please help any body.