PCF8574 I2C I/O expander.
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Ciao,
I need to interface a parallel bus CMOS device (the 82C54, a Programmable
Interval Timer) to my BS2p through a pair of PCF8574 I2C I/O expanders, to save
the I/O ports of the Stamp. But I didn't understand the operation of the quasi
bi-directional port of the PCF8574, as described in its data-sheet.
I need to know:
- whether I could tie the I/O pins of the PCF8574 directly to the 82C54, in case
of inputs (e.g. data lines) or outputs (again data, address, /WR, /RD, /CS
lines);
- what's the power-on default configuration of the port (if inputs or outputs,
and if low- or high-level).
Thanks in advance,
Alberto.
[noparse][[/noparse]Non-text portions of this message have been removed]
I need to interface a parallel bus CMOS device (the 82C54, a Programmable
Interval Timer) to my BS2p through a pair of PCF8574 I2C I/O expanders, to save
the I/O ports of the Stamp. But I didn't understand the operation of the quasi
bi-directional port of the PCF8574, as described in its data-sheet.
I need to know:
- whether I could tie the I/O pins of the PCF8574 directly to the 82C54, in case
of inputs (e.g. data lines) or outputs (again data, address, /WR, /RD, /CS
lines);
- what's the power-on default configuration of the port (if inputs or outputs,
and if low- or high-level).
Thanks in advance,
Alberto.
[noparse][[/noparse]Non-text portions of this message have been removed]