Dejair Jose Muner <deja@ST.COM.BR> wrote:

> >I am seeking a simple project for read and write eeprom 24C01.

and Alex Torres replied:

> If You want to read and write it with PIC -
> see App.Notes at the M-chip's CD or WWW.

These are crap.

> If you want do this from PC see here (You need Borland Pascal 7.0) :
> { Connect to LPT port:
> D1 ------- 1 (A0)     (Vcc)  8 -------------- D1
> D2 ------- 2 (A1)               7 ----
> D3 ------- 3 (A2)     (SCL) 6 -------------- D2
>               4 (GND)  (SDA) 5 -------------- ACK
>                          c ----------------|----R=15k---D1(Vcc)
> D0 ----R=1k0---b
>                          e--- gnd
>                   n-p-n, 2n2222, etc. Coll connected with SDA.

If you want to drive I2C with minimum hardware,
obey the I2C spec properly, and suit other I2C devices, use:

STB <---> SDA
AFD <---> SCL
GND ----- GND

STB and AFD are already open collector outputs with pullups,
and you can read their pin logic levels back.

In Alex's cct, SCL is driven by D2.
You can get away with this - the EEPROM never needs to
wait-state the I2C bus by holding SCL low.
But suppose you decide to talk to a device that may
need to do so, then D2 may try to drive high while
the device tries to pull low - undesirable!

Cheers, KH.

; Quote of the day:
; "Better a bottle in front of me than a frontal lobotomy"
; - W.C. Fields, I think.