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[SOLVED] STM8s003 getting reset with noise

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HELLO ...

Have made a voltage stabilizer using stm8s003 . one problem arises, the controller gets reset, when
1> relay operates. have used snubber, and diode across coil, but nothing seems to work.
2> when i touch mutimeter's probe at relay contact points(transformer's voltage tap).

not able to short out the problem. is there any suggestions??
Transformer is auto-type(non isolating/ common neutral)
given 1uF at Vcap.
given decoupling capacitors and electrolytic(470uF/100uF) capacitors at I/O of 7805
 

With no layout or schematic to see, no useful recommendation to give. Anyway, the first issue indicates a routing issue, likely you have not provide enough clearance from relay to the remaining circuit.
 

a very thanks for the response. :)

i have connected vcc with external wire. as the track was too long, may be this was generating noise. but got no result.

pcb_fb.jpg
pcb_fb1.jpg

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i dont think routing can be a problem . because prior this PCB, have used stm8s development board. in that also problem was same. and also,when tried with AVR controller. all were working good.
andre_teprom said:
Anyway, the first issue indicates a routing issue, likely you have not provide enough clearance from relay to the remaining circuit.
Click to expand...
 

usually to avoid unnecessary reset it is used R to Vdd and C to gnd chains.
 
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thanks.. will try with it,if it help me out.. :thumbsup:
 

i dont think routing can be a problem . because prior this PCB, have used stm8s development board. in that also problem was same. and also,when tried with AVR controller. all were working good.
Click to expand...
As said before, in dealing with relays, everything matters, particularly the layout of the board. In case, if I understood correctly by the poor resolution of the above image, did you really cascade the ground of the driver transistors? In adittion, are there GND planes (or dead plane) routed with a minimal clearance to the other tracks ?

BadRouting.png
 
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Hi,

I vote for PCB layout problem.
* a copper pour is far away from being a GND plane.
--> use a true GND plane that gives a reliable, low impedance reference for all other signals.

Like Andre says: cascading GND nodes carrying switched high currents is a no-go. You take it to the extremes because at the very end of the cascade there is the microcontroller.

Another example:
C7 is the decoupling capacitor for the voltage regulator. It needs short and wide traces to connect pin2 with pin3 of the regulator.
If you move the capacitor 3mm up, then you have direct access to pins 2 and 3...and you will reduce stray inductance maybe to 1/10.

Imagine:
It's like building a house on a couple of steel ropes instead of solid concrete.

If you have a fast scope you will see voltage spikes between different nodes of GND ... I assume they will be in the range of 2V.

Klaus
 
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HI....
both of your are going be very useful for me in future to design pcb...
a very very thanks for guiding me... :clap::p

deepone's words worked ... by adding resistor to NRST stopped reset.

andre_teprom said:
As said before, in dealing with relays, everything matters, particularly the layout of the board. In case, if I understood correctly by the poor resolution of the above image, did you really cascade the ground of the driver transistors? In adittion, are there GND planes (or dead plane) routed with a minimal clearance to the other tracks ?

View attachment 139961
Click to expand...

KlausST said:
Hi,

I vote for PCB layout problem.
* a copper pour is far away from being a GND plane.
--> use a true GND plane that gives a reliable, low impedance reference for all other signals.

Like Andre says: cascading GND nodes carrying switched high currents is a no-go. You take it to the extremes because at the very end of the cascade there is the microcontroller.

Another example:
C7 is the decoupling capacitor for the voltage regulator. It needs short and wide traces to connect pin2 with pin3 of the regulator.
If you move the capacitor 3mm up, then you have direct access to pins 2 and 3...and you will reduce stray inductance maybe to 1/10.

Imagine:
It's like building a house on a couple of steel ropes instead of solid concrete.

If you have a fast scope you will see voltage spikes between different nodes of GND ... I assume they will be in the range of 2V.

Klaus
Click to expand...

yes, i was getting some high frequency between gnd to gnd. but i thought it was some false signal. :laugh:

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HI...
a very thanks to u. by adding resistor to NRST solved my problem. i was suffering from this since a month.
many many thanks ... :clap::clap::clap::p:bsdetector:


DeepOne said:
usually to avoid unnecessary reset it is used R to Vdd and C to gnd chains.
Click to expand...
 

Hi,

by adding resistor to NRST solved my problem.
Click to expand...
I assume with the existing layout sooner or later you will encounter new EMC problems.

Klaus
 

Hi...
yes. theres a lot of noise...i am modifying layout as per both of suggestions ... 8-O

KlausST said:
Hi,


I assume with the existing layout sooner or later you will encounter new EMC problems.

Klaus
Click to expand...

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how do i remove cascading gnds?? Since all are going to connect the gnd only...

Have removed copper pours. but whats the difference between GND pour and GND plane??
 
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