Re: I2C 24C02 Eeprom Read / Write Issues
Date: July 01, 2014 07:33PM
Hi eliotroyano,
connecting a wire between MCU Xtal pads is acceptable to avoid MCU to start executing its program. Then you could try to read / write the eeprom with the programmer.
P.S: Vcc voltage 4.75V is OK.
Best regards
sonix
eliotroyano Wrote:
-------------------------------------------------------
> sonix Wrote:
> --------------------------------------------------
> -----
> > Hi eliotroyano,
> >
> > I think, there are two possibilities why the
> > communication from/to programmer is not
> > functional. The supply voltage of the eeprom
> and
> > also the voltage level on the i2c bus are lower
> > then the programmer needs for proper function.
> And
> > the second option is the collision of data on
> the
> > bus due simultaneous communication from/to an
> > AN87C196 MCU. You can try to interrupt SCL and
> SDA
> > wires to MCU and then to communicate with the
> > eeprom, but I recommend you to read / write the
> > eeprom externally (not in original circuit)
> with
> > the programmer. In this case don't forget to
> > supply the eeprom with 5V on the Vcc, pins 1-4
> and
> > 7 to GND if you would like to use the simple
> > programmers (2 resistors, 2 zener diodes and
> db9
> > rs232 connector) as you have tried.
> >
> > Best regards
> >
> > sonix
> >
> > eliotroyano Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > Hi sonix I understand you, there is no too
> much
> > > info about this topic.
> > > Ok here are my answers:
> > >
> > > 1. Which connection between the SI-Prog and
> the
> > > computer is used (serial, parallel...) ?
> > > I have been trying with some serial
> programmers
> > > like this one -->
> > >
> >
> http://sodoityourself.com/hacking-ibm-thinkpad-bio
>
> >
> > > s-password/ or this
> > >
> >
> http://www.llamma.com/xbox/Repairs/Reading_Xbox_Hd
>
> >
> > > d_key.htm
> > > I also I tryied using a GQ-3X programmer
> > without
> > > luck.
> > >
> > > 2. Which version of PonyProg do you have ?
> > > I have been using the last one in the
> download
> > > page, V2.07c.
> > >
> > > 3. What is the result message from PonyProg
> > basic
> > > I/O port diagnostics (menu "Setup>Interface
> > > Setup>Probe) ?
> > > Using the first circuit I got test failed.
> But
> > > with the second one with DB9 pins 6 and 7
> > > connected I got Test OK!!!.
> > >
> > > 4. Is the eeprom (not in the original
> circuit)
> > > connected through the "I2C Bus eeprom
> adapter"
> > > from ponyprog site below ?
> > > No the eeprom is in it original circuit,
> > matched
> > > to it MCU. My idea is to avoid
> desolder-solder
> > > avoinding continuos iteractions. In other
> words
> > I
> > > need an ISP interface for that I2C eeprom.
> > >
> > > 5. Have you tried to read/write another i2c
> > eeprom
> > > ?
> > > Just with the GQ-3x programmer. But it work
> > quite
> > > good.
> > >
> > > http://www.lancos.com/siprogsch.html
>
> Sonix thanks for your fast replay. I understand
> that easier option is to take out the eeprom from
> the circuit. I have do it in the past with sucess.
> But to avoid doing it several times, I ask for the
> ISP option.
>
> During my test I saw that Vcc voltage of 24C02 is
> 4.75V and not 5V as you mention. But I don't think
> that 4,75V as VCC for the serial eeprom should be
> a problem due that MCU read and write it with that
> low voltage.
>
> Ok then to avoid MCU uses the I2C bus (collision
> data) I have read about a trick to avoid MCU
> start. Connecting a wire between MCU Xtal pads I
> could energize all circuit but avoid that MCU
> start and also communicate with serial eeprom.
> What do you think?