Service Forum

[Jeb330]

Victor,

I'm in trouble. I've been using the simple-i2c and have been successful in reading and decoding the contense of R30/31/32's, all have had 8 pin eeproms. I've now got a T20 with a 14 pin eeprom. It refuses to read.

After many attempts, I've now developed CRC 175. Opps... clipped the wrong pin.

Any thoughts about why failures to read the eeprom. I connected
6 GND, 8 SDL, 10 SCA. Would I be better using the driven programmer?

With W24RF08 and a T20.bin would I be able repair the eeprom?

Thankyou.

[victor]

There's nothing special with 14 leads eeprom. T20 is one of the most ordinary IBM laptops and SIprog must perform very well on this machine.
You said" Opps... clipped the wrong pin". Well, exactly as I tought.
Are you still unable to read the eeprom? Even with CRC you can read the eeprom but obviously you need W24RF08 to write. We can correct the old dump w/o problemsl, send me the file to see.

Cheers

[Jeb330]

Thankyou for response.
I must have wired this 24RF08 up about 10 times, each time as pin 6 GND, 8 SDL, 10 SCA. Only after many tries did I miss
clip

Must be something wrong with T20 or manybe the chip. It's connected correctly but still can't read. I keep getting ERROR: Eeprom not avaliable! I can read my R32 reliably.... hmmm. I will buy a used T20 motherboard too try and read.

After that I'll need W24RF08, we'll talk about that later.

Thanks.

[victor]

What resistors value did you used for R1 and R2? The problem is that the laptop I2C bus impedance may be to low and your COM port cannot face this situation. Try with 2.2 KOhms.
As I said t20-23 are the most ordinary model. In fact those machines are the most used with SIPROG.
the pins are 6- GND, 8 -SDA, 10 -SCL, check again

[Jeb330]

I used values as per simple-i2cprog plans, 2.2K. Should I change to a different values or maybe try another computers COM port?

Yeah your right 6- GND, 8 -SDA, 10 -SCL, I was typing late at night, dyslexia must have been kicking in. But I'm 100% sure everything is wired correctly.

[Jeb330]

Just got my glasses out . Looks like you were right about the resistors too, I don't have 2.2K resistors in there. I'll change them out tomoorow and let you know how I go.

Thanks heaps for your help.

[bob]

Just to mention the CMOS batt & main batt must be in their places. Anyway i suggest you to check the resistance between eeprom SDA pin and Vcc and GND with an ohmeter.
If you are prompted with CRC error then the board is functional no need to buy another. Your only problem is to adapt the circuit properly to your t20 board. Anyway it is a good ideea to build a driven interface based on max232 if you plan to use on various laptop models.
Other solution is to use other PC, meaning to try with other PC COM port maybe your COM port is not adapting very well to this particulary situation