PIC Programmer

[Hero999]

I am thinking about building but I have a few questions and comments before I'll be willing to start.

What's the voltage tollerence for VPP?

I don't have the LM78L08 so I'll probably use either an LM317L or LM78L05 with a potential divider.

I don't like the way the LEDs are connected up; they all share the same series resistor, wtf?


Where's the best place to buy the TEXTTOOL 40 ZIF socket

Also, I'll probably be using my own board design (I'll be using mostly SMT components to save drilling); I take it that the layout isn't too critical?

Or should I not bother and buy **broken link removed** from Craplin (which I'd rather not do since I've already got most of the components in stock)?
?

 

[Ayne]

I think u should also look at this
**broken link removed**

 

[Nigel Goodwin]

I am thinking about building but I have a few questions and comments before I'll be willing to start.

What's the voltage tollerence for VPP?

It's not terribly critical, most of the specs call for 12V - but setting it at 13V makes a programmer more reliable.

I don't have the LM78L08 so I'll probably use either an LM317L or LM78L05 with a potential divider.

An LM317 would be fine - make sure the incoming supply is clean enough though, and ripple on the 13V will stop it working.

I don't like the way the LEDs are connected up; they all share the same series resistor, wtf?

Ask the guy who designed it! - but it works perfectly all right.

Where's the best place to buy the TEXTTOOL 40 ZIF socket

RS Components is one place.

Also, I'll probably be using my own board design (I'll be using mostly SMT components to save drilling); I take it that the layout isn't too critical?

No, it's not critical.

Or should I not bother and buy **broken link removed** from Craplin (which I'd rather not do since I've already got most of the components in stock)?
?

I don't think Maplin sell any decent programmer kits?.

 

[Hero999]

Thanks for the replies. What about the maximum voltage for VPP? Will voltages over say 14V damage it? I don't normally shop at Craplins but the minimum order RS and other places impose on me often forces me to; oh well, I suppose I'll have to bulk up my order with a few other supplies.

 

[Nigel Goodwin]

Thanks for the replies. What about the maximum voltage for VPP? Will voltages over say 14V damage it?

You might check the datasheets?, they give maximum voltages - but why worry about it?, use an LM317 and set it to 13V.

 

[Ayne]

What u say about Multi PIC Programmer 5 Ver.2.. Nigel Goodwin
I mean ur reviews

 

[Nigel Goodwin]

What u say about Multi PIC Programmer 5 Ver.2.. Nigel Goodwin
I mean ur reviews

I've never seen one, but JDM programmers are well known for their problems as they require your PC to exceed the RS232 specification - JDM is the reason WinPicProg only supports parallel port programmers!.

 

[gramo]

I've never seen one, but JDM programmers are well known for their problems as they require your PC to exceed the RS232 specification - JDM is the reason WinPicProg only supports parallel port programmers!.

Yet to have a single issue yet with my JDM's

**broken link removed** sells a great model for 19.95 US with free shipping to anywhere in the world. It supports a large range of devices, and the single 40pin ziff socket allows any of the 18/28/40 Pin micros that it supports too be programmed

**broken link removed**

 

[Pommie]

For a serial programmer, the modified JDM circuit seems to work well. You'll find a complete description on this page.

This is the actual circuit,
**broken link removed**

You don't need the 4 diodes in the middle as they are repeated inside the pic.

Mike.

 

[Nigel Goodwin]

Yet to have a single issue yet with my JDM's

Check the posts all over the net about them, including those by the original author!. The modified JDM that Pommie has posted is a more reliable option.

 

[eng1]

What's the voltage tollerence for VPP?

For example the PIC16F84 needs 13.0±0.5 V, but you may not need to use old devices? Modern PICs generate the programming voltage internally and the !MCLR line is used as level source; some enter the programming mode with 10 V (min). I use 12.7 V for most devices.

 

[Hero999]

Yet to have a single issue yet with my JDM's

**broken link removed** sells a great model for 19.95 US with free shipping to anywhere in the world. It supports a large range of devices, and the single 40pin ziff socket allows any of the 18/28/40 Pin micros that it supports too be programmed

**broken link removed**

Is it any good though? What do the other people here think?

I've found a 40 pin ZIF socket in CPC but at almoast £13 it is expensive. Does anyone know of a cheaper place? ebay maybe?
**broken link removed**

Should I just by the a complete programmer off ebay or stick at building the one from Nigel's site?

 

[evandude]

Should I just by the a complete programmer off ebay or stick at building the one from Nigel's site?

Depends, do you have a desktop PC with a good serial port? If you ever intend to use it on a laptop, or with a USB-serial converter, or if you don't trust the quality of your desktop's serial port, then it's probably not a good choice.

There are SOME similar JDM programmers showing up on ebay and elsewhere that have a connector to allow you to use an external power supply for Vpp if you wish. Can't say for sure, but it would probably give you a better chance of working on a laptop or maybe even a USB-serial. Here's one example:
**broken link removed**

Really, it's a better idea to build or buy a more reliable programmer, like a parallel programmer with a good external supply, but I understand the appeal of the dirt-cheap JDM programmers to a newcomer. Eventually, many of us come around and move up to something better

 

[Hero999]

Depends, do you have a desktop PC with a good serial port? If you ever intend to use it on a laptop, or with a USB-serial converter, or if you don't trust the quality of your desktop's serial port, then it's probably not a good choice.

Sorry but I haven't understood; do you mean it's a good choice to buy or build.

There are SOME similar JDM programmers showing up on ebay and elsewhere that have a connector to allow you to use an external power supply for Vpp if you wish.

What does JDM mean?

I'm really suprised they don't have converters to get 13V, all it would take is a voltage doubler with a 13V zener on the output.

**broken link removed**

Wow that's realy cheap!

 

[evandude]

Sorry but I haven't understood; do you mean it's a good choice to buy or build.

It doesn't matter much whether you choose to buy a premade unit or build it yourself...

What does JDM mean?

google it. JDM is a style of serial programmer, which comprises most all of the serial programmers for sale out there. It's common because it's simple and very cheap, but it has drawbacks. There are plenty of threads on the forum with information on these drawbacks.

I'm really suprised they don't have converters to get 13V, all it would take is a voltage doubler with a 13V zener on the output.

On a USB programmer I have, which originally required an external power supply, I did basically that - a simple switched-capacitor voltage tripler with the 5v USB bus voltage as input and about 13v as its output.

But, if you increase the cost and size of a JDM or other style of programmer very much by adding more fancy functionality, you start to reach the point where you might as well just get something better.

 

[bananasiong]

I have one programmer using 7812 with 2 diode in series at the reference point. No problem all the time.