What does the zero in i2c_read(0) mean?

[eastvoltresearch]

readData = i2c_read(0);

Could someone explain to me what the zero in the i2c_read(0) statement means and if it is needed ?

For example, i'm interfacing a MAX127 A/D converter and for the life of me i can't get it working.

The READ command for this IC is:

1. Send Address Byte
2. Send Control Byte
3. Receive MSB byte of data from MAX127
4. Receive LSB of data of data from MAX127

I'm using something like this:

i2c_start ();
i2c_write (0xzz);
i2c_write (0xzz);
analogvoltage.c[1] = i2c_read(0);
analogvoltage.c[0] = i2c_read(0);
i2c_stop ();

Is that right?




readData = i2c_read(0);

[PCM programmer]

Well, everything you ask is in the manual. The manual has no
table of contents, so I agree that it's hard to use. I've even
told them about it. I guess it's not a priority...

The '0' means don't do an ACK. If you look at the data sheet
for any i2c device, they usually show bit diagrams for all the
i2c transactions. On a read operation, they always show
no ack on the last byte that's read. So you need to do that.

I don't know if you have the demo or the full compiler. But with
the demo I think you don't get any examples or drivers.

Here's some test code that I've previously posted for the 24LC256.
Look specifically at the routine, read_eeprom_block(). Notice
that only the last i2c_read() gets a "no ack" parameter.
http://www.ccsinfo.com/forum/viewtopic.php?t=17036&highlight=24lc256