pic compiling/programming questions

[skyhawk]

PGM is the low voltage programming pin. It allows the PIC to be programmed without using 12V, but you lose the pin as an I/O.

 

[breadboardguy]

So instead of using vpp at 12 volts, i put pgm at? I wont be able to use it as input/ouput pin after programming?why so?

 

[be80be]

breadboardguy here all you need to know to roll your own programmer and how it works
for the 12Fxxx and 16fxxx chips https://www.electro-tech-online.com/custompdfs/2009/05/41204G.pdf I said this would be fun.

 

[skyhawk]

So instead of using vpp at 12 volts, i put pgm at? I wont be able to use it as input/ouput pin after programming?why so?

Because until LVP is disabled in the configuration word PGM must be held at ground in order for the PIC to run. LVP can only be disabled from the high voltage programming mode.

Here is the link for 16F627A/16F628A/16F648A programming specifications:

https://www.electro-tech-online.com/custompdfs/2009/05/41196g.pdf

You can read all the details there.

 

[breadboardguy]

So actually, i just need 4 wires (data in,out, programming voltage and clock)to the computer to program a pic. And ic-prog will send the right data trough the data wire and make the clock wire oscillate.
After looking at propicII i am convinced that its how it works, so now how can i configure ic-prog to put clock , vpp and data in,out where on the db9 serial port? Can i re-use the propicII configuration? So then i will have to usedo, d3, d5 and ACK.


Is data out (d0 in this case) is nescessary or a feature?(Because they dont talk of it in the prog datasheet, but it may be a needed thing for ic-prog).

 

[Sceadwian]

Breadboardguy what programmer are you using? You can't just wire an RS232 cable to a PIC and program it with this software.

 

[breadboardguy]

I (will) use a "lighter" version of propicII by only using the wires and circuitry that is need to program the 16f628a (Wich pins are shown in my last post) so it will be alot smaller but will program a limited range of pic. That is all what i was searching for.

 

[skyhawk]

So actually, i just need 4 wires (data in,out, programming voltage and clock)to the computer to program a pic. And ic-prog will send the right data trough the data wire and make the clock wire oscillate.
After looking at propicII i am convinced that its how it works, so now how can i configure ic-prog to put clock , vpp and data in,out where on the db9 serial port? Can i re-use the propicII configuration? So then i will have to usedo, d3, d5 and ACK.


Is data out (d0 in this case) is nescessary or a feature?(Because they dont talk of it in the prog datasheet, but it may be a needed thing for ic-prog).

Data out is the same pin on the PIC as data in, just program data. Its purpose is to verify correct programming, i.e. the programmer reads the program that has been entered and compares it with what was intended.

Also don't forget that the computer ground and the programmer ground must be connected together.

 

[breadboardguy]

Okay, i think that i know all what i need, i will order my pics (16f628a) very soon.
Thank for your help, i gaved you some more reputation.

I think that there is an error in propic2 sechematic, its written 4k7 for a resistor.Is it 4.7 k?

 

[blueroomelectronics]

4K7 is just the European way of saying 4.7K
Actually I got quite fond of it when I used to read my old Elektor magazines.

 

[breadboardguy]

What does power com means on the schematic?

 

[blueroomelectronics]

Power usually 5V and common represents GND

 

[breadboardguy]

For what purposes there is 4 diodes arrangement just after the power com?

 

[skyhawk]

What does power com means on the schematic?

I believe that it reads "power conn" meaning power connector, in this case the connection to the bridge rectifier (4 diodes you refer to).

 

[skyhawk]

For what purposes there is 4 diodes arrangement just after the power com?

It rectifies ac or provides polarity protection in case of dc. You can build from four diodes or buy as a single component.

 

[breadboardguy]

Can a breadboard support all the dip microcontrollers?Then i better buy this then a zif socket, wich cost 2 time more.

 

[be80be]

Yes here a 18f1320 on one **broken link removed** Just bread board it make sure you get p-dip chips like 16f628a-I/P

 

[breadboardguy]

I think that i will get some 18f too, they have 20x more ram.

 

[Sceadwian]

High frequency (basically anything over about 10mhz) crystals can't usually be run on a breadboard, this isn't a problem if you use the internal oscilator, but if you intend to use crystals you'll need to keep it in mind.

 

[3v0]

High frequency (basically anything over about 10mhz) crystals can't usually be run on a breadboard, this isn't a problem if you use the internal oscilator, but if you intend to use crystals you'll need to keep it in mind.

Some PIC's include a PLL which can be used with an extrenal crystal (and sometimes the internal osc) to multiply by 4. With the PLL you can use a 10MHz crystal on the breadboard in conjunction with the PLL to get a 40MHz clock.