Resetting a slave from master mcu

[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)

[richard]

I'm doing regular ICSP programming for now

any pic programmer worth its salt can program chips that support LVP in "regular ICSP" mode without that nasty hv pulse being needed at all

[Demon]

any pic programmer worth its salt can program chips that support LVP in "regular ICSP" mode without that nasty hv pulse being needed at all

Low-voltage programming is not used by melabs programmers and should always be disabled in the configuration settings.

https://melabs.com/support/icsp.htm


I'm gonna take my PicKit4 out of storage and give it another shot.

[Demon]

crap, I figured you were a kid .....

I'm a kid at heart, and I get out of bed at the same speed as them.

..... I always put the pics in sockets, saves a lot of F-ups....

Yeah, I'd hate to notice a mistake at the end of assembling my boards.

... 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)

I finally got a few SN7407 thanks to Mr E's suggestion a while back. This runs awesome, and I have room for 6 slaves, that should be enough for my boards.




I don't have to worry about the surges up towards the Master during programming the Slave.

(Which is good, cause my MeLabs U2 programmer doesn't do LVP, and I can't get my PicKit4 to run properly).

[richard]

I don't have to worry about the surges up towards the Master during programming the Slave.

No, but the 120 ohm pullup will be a pin killer if the vdd is 5v

[Demon]

No, but the 120 ohm pullup will be a pin killer if the vdd is 5v

Yeah, I was blindly following SN7407 datasheet. I don't really care about timing, so I upped it to 1K pull-up.

[richard]

Yeah, I was blindly following SN7407 datasheet. I don't really care about timing, so I upped it to 1K pull-up.

given that I-inh max for a SN7407 gate is 40uA and a pic output pin could drive more than 20 of them and still produce a clean TTL signal.
i cannot see that signal timing would even be a consideration. just what need does the pullup fulfill ?