Ok... I'm not a electronic technician so I might by wrong it may not be used to communicate directly to the Bus (I2C).
The simpless way to explain what i need to do is: I need to control the Tx & Rx pin so that I can send a 0 or a 1 on Tx... and listen for 0 and 1 on Rx... without using a FIFO... so it goes.. when I say, not half a second later or sooner... When I say... go "Fitzpatrick, Joe" wrote: > The first issue is signal compatibility. I2C is a three wire buss (SCL, > SDA, and GND). All data travels on the SDA line, so it needs to be > tri-state and bi-directional. I2C also normally operates at VCC (typically > +5VDC or +3.3VDC). > > The external serial port on the Palm meets none of this criteria. Tx, Rx, > CTS etc. are fixed as inputs and outputs because of the RS-232 line driver. > The line driver also provides RS-232 compatible voltages (nominally +/- > 12VDC). > > The SCL line might be able to go directly to one of the GPIO lines, which > drive interrupts on the Dragonball via a transistor. But, because of the > transistor (for protection and level adaptability), you cannot use a GPIO > line (as is) for SDA. > > I suppose you could wire up an external circuit to combine Rx, Tx, and > handshaking to provide a tri-state, bi-directional SDA line. However, based > upon your description it is not clear if you system actually uses I2C. I2C > is synchronous, there is no need for a break or delay. A start condition is > a high->low transition on SDA while SCL is high. Then, the address is > clocked out, followed by a read/write bit. The slave responds with an ACK > bit, then bytes are exchanged one at a time with an ACK bit after each (no > ACK from master on last byte of read). A stop condition is a low->high > transition on SDA while SCL is high. > > You can get the Dragonball manual from Motorola and the hardware SDK for the > Palm serial port from Palm (you have to sign up for the program). > > Good Luck, > -jjf > -- For information on using the ACCESS Developer Forums, or to unsubscribe, please see http://www.access-company.com/developers/forums/
