RL-ARM User's Guide

Serial Driver

The Serial Driver handles a serial port and is required for a PPP or SLIP serial network interface. The Serial Driver is interrupt driven since polling for a new character sometimes fails at higher baud rates and some of the received characters might be lost.

The serial receive interrupt function stores incoming characters to an intermediate input buffer. The serial transmit interrupt function sends outgoing data from an output buffer to a serial port.

If you use a serial PPP or SLIP network interface, then copy the serial device driver to your project directory and add it to your project.

The required functions of the driver are:

• init_serial() - initialize the serial interface
• com_getchar() - get a character from an input buffer
• com_putchar() - put the character to an output buffer
• com_tx_active() - check if the serial transmit is active.

RL-TCPnet includes various serial device drivers for different ARM device variants. The driver filename syntax used is Serial_xxxx.c, where xxxx is the device name. The drivers are located in the \Keil\ARM\RL\TCPnet\User directory:

• Serial.c is configured for Philips LPC21xx devices. Use this driver for all Keil MCB21xx evaluation boards.
• Serial_LPC214x.c is configured for Philips LPC214x devices. This driver uses extended features which allow configuring various baud rates using built-in fractional baud rate generator.
• Serial_S3C44B0X.c is configured for Samsung S3C44B0X devices.

For ARM device variants that are not currently supported, or if you are using an external UART, use the Serial.c device driver as a template and customize it for your needs.