JDM Type programmer

[GatorGuy]

I have built a JDM style serial programmer using an external power supply to power the pic. I have read the datasheet for the 16F628A and to enter LVP I have to pull MCLR and PGM to high. RB7 is hooked to pin 4 & 8 of the serial port. PGM is to pin 3 with a 10k resistor. If I wanted to use HVP could I not pull PGM high and use 13+ volts to MCLR?

 

[Jay.slovak]

I have built a JDM style serial programmer using an external power supply to power the pic. I have read the datasheet for the 16F628A and to enter LVP I have to pull MCLR and PGM to high. RB7 is hooked to pin 4 & 8 of the serial port. PGM is to pin 3 with a 10k resistor. If I wanted to use HVP could I not pull PGM high and use 13+ volts to MCLR?

Hi,
HVP mode is always available just connecting +13V to MCLR regradless of LVP pin. I strongly recomend to disable LVP mode (it's useless) by clearing/setting LVP Config bit.

 

[GatorGuy]

I took this from the datasheet of the 16f628A. So far the JDM programmer I built isnt working. According to this schematic it should have power to Vss and Vdd.

Pin 3 of db9 to RB7
Vpp to MCLR ;which right now it is a 10k resister to Vdd
GND to Vss and Pin 5 on db9

Just to check, which db9 pin does RB6 connect to?

Should the +5 be from any of the db9 pins or can I use the external ps?

I could use all of the help I can get!

 

[Jay.slovak]

Try this, I build it myself and it works fine with Ic-prog. I didn't assemble the sockets, I just use ICSP and I have a jumper to select power (from serial port or programmed circuit)

 

[Someone Electro]

In LVP you have to pull the MCRL and LVP pin high (+5V)

 

[Jay.slovak]

In LVP you have to pull the MCRL and LVP pin high (+5V)

Yes, that's how it works. BUT if you enable LVP mode in config register, you will LOSE one pin of the PIC! You can't use it as general purpose I/O pin... so LVP mode is USELESS.

 

[Someone Electro]

I once had an LED on the LVP pin of an 16F88 and i was banging my head why the LED is not liting up.Then i found out that LVP was enabled.I hate LVP.
A waste of pins.

 

[Jay.slovak]

Yeah, exactly! I should add a note about LVP into my Sticky.

 

[GatorGuy]

**broken link removed**

Okay I tried Stolz's LVP cable and ICProg with the 16f628A and it is not writting the pic. The cable I have is a bit long. Around 5 feet. Could that be it? Or could it be my serial port?

 

[Jay.slovak]

**broken link removed**

Okay I tried Stolz's LVP cable and ICProg with the 16f628A and it is not writting the pic. The cable I have is a bit long. Around 5 feet. Could that be it? Or could it be my serial port?

5ft is a loooooong cable, try something about 10cm :lol:

 

[GatorGuy]

After studying the schem from the datasheet it shows data i/o (pin 3 of serial) to RB7. And CLK to RB6. But it doesnt say anything about PGM.

The schem for the LVP cable on Stoltz site shows DATA line 3 to PGM and other pins to RB6/7.

Should I just pull MCLR and PGM high off of Vdd and put pin 3 to RB7? What pin on the serial port is CLK?

 

[GatorGuy]

Okay I have tried two different JDM programming software and it keeps failing. I brought the cable length under 6 inches and used a meter to test all connections.

MCLR is pulled high off of Vdd with a 10k resistor.
Vdd = 5.0+ VDC ;external PS
Vss = 0+ GND from ps and to pin 5 of serial port
PGM = pin 3 with 10k resistor
PGC = pin 7 with 10k
PGD = Pin 4 w/10k & pin 8 wo/resister

Anythoughts?

 

[Someone Electro]

Is MCRL going over 12V ?

 

[GatorGuy]

Is MCRL going over 12V ?

No, 3.8<> volts.

 

[Nigel Goodwin]

Is MCRL going over 12V ?

No, 3.8<> volts.

If you're trying to use high voltage programming mode you need 13V or so on the MCLR pin to switch to programming mode.

For LVP mode the processor has to have it's config fuses set to enable LVP, otherwise you can't enter LVP mode.

The JDM 'serial' programmers are reknowned for having problems, it's far more reliable to use a parallel port programmer, or a proper serial port one.

 

[Someone Electro]

Now the PIC is runing its code. It must be 12-14 V to enter programing mode.

 

[GatorGuy]

I am trying to use LVP. Other then the LVP check box on the ICProg is there anything else I need to do? Sorry I am really new to programmers.

I just read a tutorial with another JDM style programmer using ICProg and it talks about WinXP needing special drivers. I never installed those. Could that have anything to do with it?

 

[Someone Electro]

The configuration word in the PICs memory has to alredy be set to LVP.Then You need to aply a logical high to bouth MCRL and LVP and giving it power suply to Vdd and Vss. Then the programer can start comunicating whith the PIC

 

[Someone Electro]

Oh an new PICs mostly have LVP on wen you get them.

 

[GatorGuy]

While I am hitting my head on the wall because it isnt working I had to ask this. Could the fact that my serial port runs with -11 volts have anything to do with it? Do I need to use a MAX232?