Service Forum

[crono5]

Hello i'm trying to read password with simple-i2cprog i have made the circuit, all seems to be ok. I have checked all connections with multimeter. And again all ok. Circuit have been tested with itester and results (with two 2.1 ohm resistors) :

SDA voltage:

0.77 4.7 0.77 4.7 0.76 4.7 0.77 4.70 0.77 4.7 0.77 -> SDA/SCL out

SCL voltage:

0.77 5.1 0.77 5.1 0.77 5.1 0.77 5.1

Firsts thing i though that there maybe something is wrong with the resistors (2.1 not 2.2, but any way bout SDA and SCL have got 2.1 ohm resistors, and still SDA voltage is lover than SCL.) so i replaced the SCL resistor with an potentiometer and adjusted it resistance to get same voltage. Still the same error.

Itester results:

SDA voltage:

0.77 4.7 0.77 4.7 0.76 4.7 0.77 4.70 0.77 4.7 0.77 -> SDA/SCL out


SCL voltage:

0.77 4.7 0.77 4.7 0.77 4.7 0.77 4.7


I used two zener diodes C5V1 (not shure if BZX79) and the cable plain network UTP.

Here some circuit fotos:











Ground is connected via VGA screw

[victor]

Hi there.

Can you take some better focused ones? I need to actually see how the connector is wired..

1. The voltage sense when itester shows "0" must be negative for a standard COM port. Hopefully is not some kind of USB surrogate.

2. 2.1Kohm is not much of a difference. Oh, and put the fixed resitor back!

3. Do not solder the interface's output wires directly to the eeprom, use a separate pair and connected them to the interface only after the laptop is started!
Do not power on the laptop with the interface attached to SDA and SCL wires.

And more..
_________________
Victor Voinea
ALLservice HQ, Romania.

[crono5]

Hello
3. Interface wires aren't soldered directly to the EEPROM, they are connected via switch (only SDA, earlier i connected SCL as well to make instant connection to eeperom via switch after connecting ground, but later when error occurred i decided do connect first SDA then SCL)
I use standard com port located on a standalone PC.

The sequence is:

1. Power ON
2. F1
3. Wait
4. Attaching ground ( (1'st foto in earlier post) withe + blue next to the switch)
5. switching on the switch (SDA)
6. Connecting SCL (yellow + white orange next to the switch)
7. Reding the EEPROM

De attachment of wires
First
4, 5, 6

[victor]

Well, you missed connector's pin 8, SDAin. Take a look at the blueprints again..
_________________
Victor Voinea
ALLservice HQ, Romania.

[crono5]

hehe now when You mention i see it, so called Czech error : ) i didn't see it probably because there's no part there : )

[crono5]

Hello
Well all worked like a charm many thanks for that hint But as the murphy laws goes - theres allays must be something more to do; in password line (0x340)i have got something like this: Fü×Î4đ¸m

TCPA?

Victor i send You the bin file.

[victor]

Ok, let's see it. support@
_________________
Victor Voinea
ALLservice HQ, Romania.