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/* -*- c++ -*- */
/*
* Copyright 2001,2004 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "i2c_bitbang.h"
i2c_bitbang::i2c_bitbang (i2c_bbio_sptr io)
{
d_io = io;
d_io->lock ();
stop (); // get bus in known state
d_io->unlock ();
}
i2c_sptr
make_i2c_bitbang (i2c_bbio_sptr io)
{
return i2c_sptr (new i2c_bitbang (io));
}
// start:
// entry: SCL = 1, SDA = 1
// exit: SCL = 0, SDA = 0
void
i2c_bitbang::start ()
{
set_sda (1);
set_scl (1);
set_sda (0); // SDA high -> low while SCL high
set_scl (0);
}
// stop:
// entry: SCL = X, SDA = X
// exit: SCL = 1, SDA = 1
void
i2c_bitbang::stop ()
{
set_scl (0);
set_sda (0);
set_scl (1);
set_sda (1); // SDA low -> high while SCL high
}
// write_bit:
// entry: SCL = 0, SDA = X
// exit: SCL = 0, SDA = X
void
i2c_bitbang::write_bit (bool bit)
{
set_sda (bit);
set_scl (1);
set_scl (0);
}
// write_byte:
// entry: SCL = 0, SDA = X
// exit: SCL = 0, SDA = 1
bool
i2c_bitbang::write_byte (char t)
{
int i;
bool ack_bit;
for (i = 0; i < 8; i++){
write_bit (t & 0x80);
t <<= 1;
}
// clock #9. This is the ACK bit.
set_sda (1); // tristate SDA
set_scl (1);
ack_bit = get_sda (); // slave should pull SDA line low
set_scl (0);
return ack_bit == 0;
}
// write: the high level entry point...
// entry: SCL = 1, SDA = 1
// exit: SCL = 1, SDA = 1
bool
i2c_bitbang::write (int addr, const unsigned char *buf, int nbytes)
{
bool ok = true;
d_io->lock ();
start ();
ok = write_byte ((addr << 1) | 0); // addr plus "read opcode"
for (int i = 0; i < nbytes; i++)
ok &= write_byte (buf[i]);
stop ();
d_io->unlock ();
return ok;
}
// read: the high level entry point...
// entry: SCL = 1, SDA = 1
// exit: SCL = 1, SDA = 1
int
i2c_bitbang::read (int addr, unsigned char *buf, int max_bytes)
{
d_io->lock ();
// FIXME
d_io->unlock ();
return -1;
}
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