Very Simple ICSP Programmer

JoeCJK · - 2nd April 2005, 20:16

Hi,

thks for the reply. Pls bear with me for I am a novice programmer. I connected the 16F628 chip directly to the serial port in the config as shown below:

Serial Port Pins : 16F628 Pins

TXD (Pin 3) -----[4.7K]------ MCLR ( Pin 4)

GND (Pin 5) ----------------- Vss (Pin 5)

DTR (Pin 4 ) -----[4.7K]------ RB 7 (Pin 13)

CTS (Pin 8) ----------------- RB 7 (Pin 13)

RTS (Pin 7) -----[4.7K]------ RB 6 (Pin 12)

To power up the chip, I connected the power supply to these pins on the 16F628.

Vdd (Pin 14 ) ------ + 5V
Vss ( Pin 5 ) ------ + 0V

Afterwards, I used IC-Prog and did a wirte of a hex file but was unsuccessful. No other programmer was used, just a direct serial port to chip connection. By all indications it should work right?

**NavMicroSystems** · - 2nd April 2005, 20:53

Joe,

There are a few things you could check in addition:

What are the levels on you serial port?
(if it's one of those LapTop ports with 5V levels this programmer is most likely NOT going to work).

Another issue might be a floating LVP pin (RB4/PGM on the F628)

See link "Programming Specs" posted earlier

JoeCJK · - 3rd April 2005, 07:46

Hi,

I will try it on a desktop instead of a notebook and short MCRL and the LVP pins together to raise LVP to the correct level. Will get back on wheter it works.

BTW, on the settings of the IC-Prog I do have some queries. I am not using the JDM Programmer but on the hardware options chose "JDM Programmer" ,"Direct I/0" with a time delay of 20. Not inverting any pins. Is this the correct settings on the IC-Prog?

**NavMicroSystems** · - 3rd April 2005, 13:22

Joe,

You don't really want to feed 12-14V into RB4, do you?

Have you really read the programming specs?

Have you checked the levels on your COM-port?

you could try to drop the resistor values down to 2k2 or even 1k.

if you Google for JDM you'll find many examples, schematics, etc.

BTW
A fully assembled and working JDM-type of programmer would be $9,95 only.

JoeCJK · - 3rd April 2005, 17:50

hi,

really sorry, as I mentioned, I am a novice programmer with PICs and not familiar so pls correct me if I'am wrong.

1) The chip CAN be programmed without any programmer ,eg. JDM etc, just the right serial to chip connections and IC-Prog right?

2) I've read the specs but it gets pretty confusing. Low voltage programming---The Vdd is raised first to +5V , following which MCLR and RB4 are also raised to +5V by serial connections with a 4.7K resistor(no longer 12 V from serial port) . So shorting out MCLR and RB4 should be the way?

That way, both MCLR and RB4 are raised to 5V. (LVP)

Thks, really appreciate the advice.

**NavMicroSystems** · - 3rd April 2005, 20:20

The chip CAN be programmed without any programmer ,eg. JDM etc, just the right serial to chip connections and IC-Prog right?

You need to make sure the voltage levels on all pins used for programming are within the specs.
This is actually all the JDM-programmer does.

AGAIN:

have you checked the levels on your COM-port yet?
have you read all specs?
Have you understood the concept of JDM?
are you sure your PIC is ok?
(you might have killed it with your experiments)

As long as you haven't understood what you are doing you will never get this working.

The time we all have spent on this thread is worth far more than the $9,95 a working programmer would have cost.

Why don't you just go and get one?

JoeCJK · - 4th April 2005, 10:54

The serial port voltage levels are about 5V.(notebook)

And you're probable right, I should just go and get a programmer, althought it will cost some time and a bundle in shipping fees. Will try with a smaller value resister and other stuff just one more time.

Thks.