Resetting a slave from master mcu

[amgen]

you could do in software..... send out to one or all listeners a command to goto a restart routine like.... which "provides a way to execute a MCLR in software"
,
,
,
restarting:
@ RESET

[Demon]

you could do in software..... send out to one or all listeners a command to goto a restart routine like.... which "provides a way to execute a MCLR in software"
,
,
,
restarting:
@ RESET

But will that work if the slave is caught in a loop or some such?

I'm aiming for a complete reset with no decision from the slave.

[amgen]

But will that work if the slave is caught in a loop or some such?

I'm aiming for a complete reset with no decision from the slave.

could do.........
1)
'
restarting:
pause 1000 ............... wait a second or 2 to reset all
@ RESET
'
or 2)................
if all slaves are on same 5 or 3 volt supply, then use a small NC (normally closed) relay to turn off power for few seconds to restart all slaves

[Demon]

I figured out an easier way to MCLR a PIC from another; a simple diode.




I was fixated on that darn pull-up to VDD:

- pull-down MCLR on Slave.
- 1N4001 diode from GP pin on Master.
- 100R towards ICSP.

And that's it. I just tested it, and there's never more than 5V on Master-side of diode.

I can't believe it was so simple.


I have one last test to do; check how much current is running from Master.

EDIT: I see a quick pulse of 16-17mA when I'm programming via ICSP. I'm not sure how I can manage that.

[amgen]

MCLR's have internal weak pullups in chip.....

[Demon]

What diode are you using? Did you put it on backwards?

Like Ioannis said, ICSP runs a whole bunch of volts through that line.

[Demon]

I got my better multimeter and got:

- 15mA surge
- 0.43mA continuous

The surge is just that, an instantaneous burst. Considering I/O pins on the 16F18877 are rated for absolute maximum 50mA, and most PICs are rated for 2-25mA, I don't think a burst of 15 or a few more mA is something to be worried about.

[Demon]

could do.........
1)
'
restarting:
pause 1000 ............... wait a second or 2 to reset all
@ RESET
'
or 2)................
if all slaves are on same 5 or 3 volt supply, then use a small NC (normally closed) relay to turn off power for few seconds to restart all slaves

What is the @ RESET command? (I'm using PBP3.1)

I prefer to avoid relays and mechanical devices. Contacts generally consume more current than ICs and discretes, and contacts wear out.

I've got an order for some SN7407N from Digikey; gonna check out Mr E's suggestion.

[amgen]

diodes can be like signal diodes 1N4148. Not backwards in order to pull MCLR low to reset and that is considering you do LOW VOLTAGE PROGRAMMING setting, if not doing that then would use the 2n3906 or any NPN to pull down all the slaves through the diodes. The @ RESET is an assembly instruction using the @ for PBP to do machine code directly ( I think you know all that stuff)...... so if you want a hard reset after ICSP then yes to use MCLR but if chips are running, you could give instruction to GOTO reset.

[Demon]

... diodes can be like signal diodes 1N4148. Not backwards in order to pull MCLR low to reset and that is considering you do LOW VOLTAGE PROGRAMMING setting...

Nah, I'm doing regular ICSP programming for now, but I'm considering using ZIF socket adapter for programming, and then installing the PICs on IC sockets.

The nice thing with IC sockets, I can't damage the PIC while soldering. A dab of hot glue at both ends should stop the PIC from falling out.

... The @ RESET is an assembly instruction using the @ for PBP to do machine code directly ( I think you know all that stuff). ...

I graduated back in '83, was 2nd in my assembler classes. But I've never used it in my professional career as mainframe programmer.

... if not doing that then would use the 2n3906 or any NPN to pull down all the slaves through the diodes.

Can you explain this like I'm 5? I looked at NPN and PNP transistors but I can't figure out how to do that.

[amgen]

crap, I figured you were a kid ..... I always put the pics in sockets, saves a lot of F-ups. For transistor, logic level MOSFET is good to use. The logic level means it will be full on with 5 volts on gate, no resistors required.... N-channel like BS170 ... with this, the reset is a high pulse on master...(dah)