The following table shows the serial port driver platform dependent driver (PDD) functions.
| Programming element | Description |
|---|---|
| GetSerialObject | This function returns a pointer to a HWOBJ structure. The structure contains the function pointers and parameters for the hardware interface functions of the relevant lower layer. |
| HWClearBreak | This function clears an RS-232 line break condition. |
| HWClearDTR | This function clears the Data Terminal Ready (DTR) signal. |
| HWClearRTS | This function clears the Request to Send (RTS) signal. |
| HWClose | This function closes the device initialized by the HWInit function. |
| HWDeinit | This function is called by the upper layer to de-initialize the hardware when a device driver is unloaded. |
| HWDisableIR | This function disables the infrared (IR) serial interface. |
| HWEnableIR | This function enables the infrared (IR) serial interface. |
| HWGetCommProperties | This function retrieves the current properties of the communications device. |
| HWGetIntrType | This function returns the current interrupt type. |
| HWGetModemStatus | This function retrieves the modem status. |
| HWGetRxBufferSize | This function returns the maximum number of bytes that the hardware buffer can hold, not including the padding, stop, and start bits. |
| HWGetRxStart | This function returns the start of the hardware-receive buffer. |
| HWGetStatus | This function specifies the hardware status API. |
| HWInit | This function initializes a serial device. |
| HWIoctl | This function executes device I/O control (IOCTL) routines. |
| HWLineIntrHandler | This function handles line interrupts for serial port devices. |
| HWModemIntrHandler | This function handles the modem interrupt. In the serial port upper layer implementation available in Microsoft Windows CE 3.0 and later, this function replaces the HWOtherIntrHandler function. |
| HWOpen | This function is called by the upper layer to open the serial device. |
| HWOtherIntrHandler | In Windows CE 3.0 and later, this function has been replaced with the new function HWModemIntrHandler. |
| HWPostInit | This function performs necessary operations after it initializes all data structures and prepares the serial IST to begin handling interrupts. It is called by the upper layer. |
| HWPowerOff | This function notifies the platform-dependent driver that the hardware platform is about to enter suspend mode. It is called by the model device driver (MDD). |
| HWPowerOn | This function notifies the platform-dependent driver that the hardware platform is resuming from suspend mode. It is called by the MDD. |
| HWPurgeComm | This function purges the communications device. |
| HWPutBytes | This function writes bytes to hardware. The driver calls this function. |
| HWReset | This function resets the hardware API. |
| HWRxIntrHandler | This function handles serial port interrupts. |
| HWSetBreak | This function sets the line break condition on the transmit line. |
| HWSetCommTimeouts | This function sets the communications time-out events in response to a call to the SetCommTimeouts function. |
| HWSetDCB | This function sets the device control block. |
| HWSetDTR | This function sets the Data Terminal Ready (DTR) signal. |
| HWSetRTS | This function sets the Request to Send (RTS) signal. |
| HWTxIntrHandler | This function handles the transmit interrupt for serial port devices. |
| HWXmitComChar | This function transmits a single character. |
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