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Interfacing to the X24F128 2-Wire SerialFlash Memory

Vcc Vcc

Application Note
Interfacing to the X24F128 2-Wire SerialFlash Memory
Vcc Vcc
Connector DB25
74LS07
Figure 1 - Simple interface between 2-wire serial memories and a parallel printer port on a PC.
SerialFlash
is a trademark of Xicor, Inc.
Xicor, Inc. · 1511 Buckeye Drive · Milpitas, CA 95035 · (408) 432-8888
AN84-1
Xicor Application Note
/ set SDA bit at port / / compensate for high bus capacitance /
/ reset SDA bit at port / / compensate for high bus capacitance /
/ generate I2C start condition /
AN84-2
Xicor Application Note
/ generate clock pulse and read SDA /
/ read parallel port / / isolate SDA / / shift to LSB / / and return data /
/ master sends acknowledge /
/ master receives acknowledge /
/ master sends a byte /
AN84-3
Xicor Application Note
/ ack polling loop / / slave address / / check SDA level / / repeat while SDA is HIGH / / SDA is LOW so stop /
/ construct second address byte /
/ yes / / send program protect register address /
AN84-4
Xicor Application Note
/ begin nonvolatile write cycle / / poll for cycle completion /
AN84-5
Xicor Application Note
AN84-6
Xicor Application Note
/ write PPEN, BL1, and BL0 bits, / / reset RPEL, leave PEL bit set /
/ poll for cycle completion /
/ buffer to store bytes from SerialFlash /
set PEL bit / set RPEL bit / write to PPR (PPEN, BL1, BL0) / read PPR / write first sector / write second sector / random read of 2 sectors / for verification of writes / sector write / verify sector / set RPEL bit / write PPR and set BlockLock for / the entire array / read and verify PPR / attempt a sector write / verify sector was not changed / set RPEL bit / write PPR and turn off BlockLock / read PPR / random read of sector / current address read of sector / sector write / random read of sector /
AN84-7