Hi Matias, Can you post a schematic and board layout? In particular, what kind of decoupling from the power supply are you using for the PIC, and what kind of circuit do you have connected to MCLR? Is the path between your bulk capacitance supply and the PIC shared with any higher current switched loads? If you can do some in-circuit debugging, it may help to know what the reset source is (usually in a register called RCON but I can't remember what the config is for the 16f877). Thanks, Tony Matias Vidoni wrote: > The diodes are in their place to suppres the spikes. I forgot to tell. > I will try the bigger cap when I come back from the office. > Thanks by now > > On Wed, Mar 17, 2010 at 10:08 AM, Carl Denk wrote: > >> I use many 40 amp 1" cube automotive relays with 12 VDC coils. The >> sockets are available with the diodes installed. >> >> On 3/17/2010 8:25 AM, Peter Feucht wrote: >> >>> Hi, >>> >>> For me it sounds like missing spike suppressor diodes. >>> >>> As long as several relays are activated the spikes, which are generated by >>> swiching off another coil will be suppressed by still activated relay coils. >>> But when you switch off the last relay there is nothing left which would be >>> able to supress the spikes... >>> >>> Just add a common diode (1N4148 will do) across each relay coils. >>> >>> Regards >>> >>> Peter >>> >>> Hi people >>> I have a circuit where I have a pic16f877 that commands four water pumps. >>> The connections between the pic and the pumps is made this way: >>> PIC -> 5k6 resistor -> Bc337 transistor -> relay -> contactor -> pump I >>> start the pumps in secuence and when a presure sensor signals, I shut down >>> every pump one by one. >>> When the last pump stops, the pic resets, and it should not. >>> Could it be my interface pic-pump the problem? >>> Could it be some EMI interference from contactors or pumps resetting the >>> pic? >>> The most strange thing is that it resets only when the last pump power off. >>> the software is ok, because I put the circuit in my workbench, with leds >>> simulating the pumps and it works great. >>> If somebody has a clue, let me know. >>> Thanks a lot! >>> Matias >>> >>> -- >>> Matias Vidoni >>> eMail: matiasvidoni@mvcom.com.ar >>> MSN Messenger: matiasvidoni@mvcom.com.ar >>> Skype: matiasvidoni >>> WWW: http://www.matiasvidoni.com.ar >>> Google Talk: matiasvidoni@gmail.com >>> -- >>> http://www.piclist.com PIC/SX FAQ& list archive View/change your membership >>> options at http://mailman.mit.edu/mailman/listinfo/piclist >>> >>> >>> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> > > > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist