Palm OS Programming, 2nd Edition

Serial Communications

The original version of the Serial Manager was a shared library that provided access to the one and only serial port on the device. The 3.3 OS introduced some important changes, including a new Serial Manager, which is no longer a shared library. Your code no longer has to call SysLibFind to load the library before using it. The new Serial Manager provides the following:

• Support for multiple serial ports. You can specify either logical ports (such as the cradle port), physical ports (such as the port controlled by a particular UART), or virtual ports (such as an IrComm infrared pseudoserial connection). The Connection Manager provides a way for users to configure and specify ports.

• Support for serial drivers. These drivers can be either physical drivers that control some serial hardware, or virtual drivers that emulate serial drivers (by sending and receiving data in some fashion other than serial). The IrComm serial-over-IR is implemented using a virtual serial driver that handles sending and receiving using the Infrared Library APIs. We won’t cover how to write serial drivers in this book.

Tip

IrComm is an industry standard that defines a protocol for using infrared to emulate a serial port. It is used by legacy serial applications that haven’t been rewritten to support infrared.

• Backward-compatibility for the old Serial Manager. Code that uses the old Serial Manager will work.

There is a great deal of similarity between the old and new Serial Managers. ...