multiple reset (2xUNO's & 2 MEGA)

Hi all,

i’ve got a timing problem, for a time sensitive project.

i’m working on a project that i,volves 2 UNO’s & 2 MEGA’s. (see picture attached)

They are used for a sort of chronodevice for dogsports.

you can picture it as two independent chrono’s that need to be reset (restarted) by one single button.

all devices share the same ground and VCC, powered from batteries, through a step-down buccle.

from my button i go to the first UNO, from there on i go to the first MEGA, then to the second MEGA, and then to the second UNO.

the UNO’s display some messages on a 8x8 display (one display per UNO)
now, yesterday, i saw that the closest UNO to the button was earlier in displaying it’s message than the second UNO (that’s the last device in the chain)

my brief knowledge of electrics have me the idea that all devices would reset at the same time, thus the UNO’s displaying their message at the same time

this was not the case, the first UNO was clearly visible earlier with it’s message than de second UNO

would it be better to connect the button through 4 wires directly to the separate devices, instead of linking then in a chain??

i’m not that good in electronics or arduino to figure this one out myself

any help would be much appreciated :slight_smile: