Some problems about connecting a screen with multiple connections to the propel

Michel L

I would like to connect a screen with multiple connections to the propeller.

It has a normal RS232 connection and a "General Port Connector". In the pdf with specifications following thing is written about the "General Port Connector":

This connector enables you to connect the second RS232 port (5 Volt signals only, no standard RS232
signal level of ± 9 Volt), the I2C, and some other signals described below.

And following are the most relevant parts from the electrical specifations table

Item                                      Symbol         Condition           Min.         Typ.          Max.          Unit
Supply Voltage                             VCC               -               4.75         5.0           5.25             V
RS-232 Input Voltage
Operating Range                                                                                        ±30              V
RS-232 Input Threshold
Low                                         VIRL            VCC = 5V          0.8          1.3                        V
RS-232 Input Threshold
High                                        VIRH            VCC = 5V                        1.8           2.4          V
RS-232 Input Hysteresis                     VIRH            VCC = 5V        0.2           0.5             1               V

I must say I have absolutely no idea with wich of the to ports i need to connect it and also If and wich resistors should be user?
Also with the "General Port Connector" it is possible to use I²C. Is this preffered or not. I never used I²C and don't know anything about it.
It needs 3 connectors in according to the specifications of the screen:

• I2C Data (witch has to be pulled high, according to this specification)
• I2C Clock (Don't have an idea for what, i don't believe RS232 has this?)
• I2C Alert – signals unexpected data to be sent to the application (e.g. a keystroke) (is this a normal I²C line?)

Could anyone give me more information about this? (=I²C and what to chose)

Thanks in advance

Javalin

Well for the i2c stuff - look at the i2cObject (s) in the propeller object library. Sample code and objects etc are available there to run I2C. In mine (i2cObject v1.3) the i2cDemoApp.spin contains documentation of the wiring used which may clarify.

Looks like your screen is a +5v screen - so put 1k resistors on the serial between the prop and the screen and it will be fine. With the i2c follow the i2cDemoApp.spin documentation.

Cheers,

james