GP2X Rtc Module

[sephiroth111]

now, assuming that we found the bus lines, (also a 3.3v power, which isn't hard in the gp2x) who's to say that the I2C bus isn't taken up by some other device (or is that impossible for it to be taken up?) because if I remember correctly, windows was shouting about there being some sort of i2c gadget connecting to it (the gp2x).

so would it still be possible to place a device on it, assuming that the bus is taken?

edit: would this chip be compatable with the GP2X's bus protocol? http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3696 (you can get a sample of it for free to test, so it makes life easier.)

edit2: apparently its possible. (from:http://www.xs4all.nl/~ganswijk/chipdir/abc/network/i2c.htm)
The master usually determines the clock speed, but a chip on the bus can slow the transmission down, by prolonging the cycles. The data can from the master to the slave or the other way around, depending on the kind of chip that is being addressed. Different kinds of chips have different byte-addresses on the bus and you can usually also buy an A-version of a certain chip that has a slightly differend address, so it's possible to connect two of each kind of chip to a single bus.

so it looks like we can just tack it on to the system.

 

[BradN]

now, assuming that we found the bus lines, (also a 3.3v power, which isn't hard in the gp2x) who's to say that the I2C bus isn't taken up by some other device (or is that impossible for it to be taken up?) because if I remember correctly, windows was shouting about there being some sort of i2c gadget connecting to it (the gp2x).

so would it still be possible to place a device on it, assuming that the bus is taken?

edit: would this chip be compatable with the GP2X's bus protocol? http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3696 (you can get a sample of it for free to test, so it makes life easier.)

edit2: apparently its possible. (from:http://www.xs4all.nl/~ganswijk/chipdir/abc/network/i2c.htm)
The master usually determines the clock speed, but a chip on the bus can slow the transmission down, by prolonging the cycles. The data can from the master to the slave or the other way around, depending on the kind of chip that is being addressed. Different kinds of chips have different byte-addresses on the bus and you can usually also buy an A-version of a certain chip that has a slightly differend address, so it's possible to connect two of each kind of chip to a single bus.

so it looks like we can just tack it on to the system.

Many I2C devices have a few external pins that can be tied to VCC or ground to alter some bits of the address. EEPROM chips are usually like this. Also, I2C is such a simple protocol, you could connect a device using any extra GPIO pins laying around (sometimes you can get away with it even if the data line is shared with some other function, like a LED or switch input, etc, just so long as you can keep other processes from interfering while you use it)

 

[sephiroth111]

{snip}
Many I2C devices have a few external pins that can be tied to VCC or ground to alter some bits of the address. EEPROM chips are usually like this. Also, I2C is such a simple protocol, you could connect a device using any extra GPIO pins laying around (sometimes you can get away with it even if the data line is shared with some other function, like a LED or switch input, etc, just so long as you can keep other processes from interfering while you use it)

looking at the wiki though, there really isn't much in the way of GPIO pins available
(http://wiki.gp2x.org/wiki/GPIO_Reference)
if its just a daemon on bootup, could we use something like the jtag pins (uart0 in the wiki)? that would eliminate any massive seek and solder jobs.