Oscillator stops when touching with a wire

[Wilbert Ingels]

Good evening all,

I've made a RS485 network of 16 remote devices (16F886) and 1 master (18F2620) all running Picbasic pro. Everything runs perfectly, however, when i touch the ground or one of the inputs with a non connected wire (to connect an input with the ground for example), the clock stops running (wire is only connected on one side).

I've tried to change the capacitors of the xtal (changed it between 15pf and 22pf) but the result remains the same.

PIC's are configured in HS mode.

Any ideas how to solve this?

Many thanks !!

Wilbert

[skimask]

Good evening all,
I've made a RS485 network of 16 remote devices (16F886) and 1 master (18F2620) all running Picbasic pro. Everything runs perfectly, however, when i touch the ground or one of the inputs with a non connected wire (to connect an input with the ground for example), the clock stops running (wire is only connected on one side).
I've tried to change the capacitors of the xtal (changed it between 15pf and 22pf) but the result remains the same.
PIC's are configured in HS mode.
Any ideas how to solve this?
Many thanks !!
Wilbert

How about decent cap's across Vdd and Vss?
Do you have a pull up on MCLR?

[mister_e]

AND
1.make sure LVP is set to OFF on both
2.make sure ALL Vss & Vdd are connected.

If both run @5V, it shouldn't be a Brown-Out reset or... sort of.

[Wilbert Ingels]

Thanks for the replies !

Just to come back on the below feedback:
- Caps are used to stabilize power supply (100nf and 10mf) and also every PIC has a 100nf cap on the power supply pin
- MCLR has a pull-up resistor
- LVP set to off

Other ideas what it could be?

I can post the network drawing (Eagle file) but i'm not sure if i can attach files ...

Many thanks for helping me with this !!

Wilbert

[Wilbert Ingels]

Also the 2 VSS pins are connected ...

[mackrackit]

How good / stable is you power supply?

[Wilbert Ingels]

Some additional information:
- The processor doesn't reset but stops in my opinion. I've used debug information on a serial port. On each startup, an appropriate message is sent (which i don't receive when this problem occurs). I'm also displaying variables and when the processor continues, he still has the right values.
- Most of the cases, information on the RS485 network triggers the processor to continue.