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The SPIF is set when a data transfer is complete, and is cleared by a read of the SPSR status register, followed by a read or write to the SPDR data register. The MODF bit is cleared by a read of the SPSR followed by a write to the SPCR. If the /SS pin of the master is an input and if a low input level is detected, the processor sets the MODF bit in the SPI status register a "mode fault" condition. If your computer does not have an RS-232 serial port, low cost USB-to-RS-232 serial cables are available; contact Mosaic Industries for details. If your computer does not have an RS232 serial port, low cost USB-to-RS232 serial cables are available; contact Mosaic Industries for details. Please contact Mosaic Industries if you need this custom configuration. Contact Mosaic if you require RS485 signals to be routed to the DB-9 Connector.

Two RS485 transceivers are present on the PDQ Board, one for each channel. Data translation between different machines can be performed with ease, rs485 cable and applications that communicate via the primary serial port can be debugged using the secondary channel. Since both channels can operate simultaneously and independently, serial debugging can be performed while the application program is communicating via its primary channel. The advantage of using Serial1 for RS485 is that the Serial1 RS485 signals are also available on the Docking Panel, while the Serial2 RS485 signals are available only on the PDQ Board’s Serial Communications Header. Two devices are at the ends of the cable, while others are connected somewhere in between. The interface can be used to support analog to digital and digital to analog converters, networks of many computers controlled by a single master, or networks of devices controlled by several coordinated masters. The flexibility and power of the 68HC11’s serial peripheral interface supports high speed communication between the 68HC11 and other synchronous serial devices. Slave devices use the master in/slave out pin, MISO, for transmitting, and the master out/slave in pin, MOSI, for receiving data. The primary and secondary serial communications ports are accessible through the PDQ Board's 10 pin, dual row Communications Header (H2) and through the Docking Panel's 10 pin, right-angle, dual row Communications Header (H1) and individual DB-9 Serial 1 and Serial 2 connectors.

There are surface-mount resistor pads on the Docking Panel to bring out the RS485 signals to the DB9 Serial 1 Connector. A jumper labeled "2 485En" (J7) enables RS485 operation on the Serial2 port if the jumper cap is installed, and configures Serial2 for RS232 operation if the jumper cap is not installed. A jumper labeled "1 485En" (J4) enables RS485 operation on the Serial1 port if the jumper cap is installed, and configures Serial1 for RS232 operation if the jumper cap is not installed. Extended range. Reliable operation at distances far beyond the conventional RS485 limit. Enabling RS485 on the Serial2 port is parallel to the process described above. After a factory cleanup, Serial1 is the default serial port for program development and downloading. The default serial routines used to download programs to the operating system assume that full duplex communications are available, so you cannot use the RS485 protocol to program the controller. RS485 is another protocol supported by the primary serial port on the PDQ Board. Each serial port can be configured for the RS232 or RS485 protocol, and runs at standard baud rates up to 115,200 bits per second. If PT is cleared, then all transmitted bytes with a parity bit will have an even number of total '1' bits.

The Serial 1 and Serial2 ports can be configured for either RS-232 or RS-485 communications at standard baud rates up to 115200 bits per second. These characteristics make RS-485 useful in industrial control systems and similar applications. If you have not yet compiled the GETSTART program and you want to do the exercises here, open GETSTART.C in your TextPad editor, click on the Make Tool, and after the compilation is done, enter Mosaic Terminal by clicking on the terminal icon and use the "Send File" menu item to send GETSTART.DLF to the QScreen Controller. All of the serial ports are supported by pre-coded C-language software drivers that make it easy to exchange data. First you need to download the software. Rather, it relies on software handshaking via transmission of XON/XOFF characters (ascii 0x11 and 0x13, respectively) to coordinate data transfer and ensure that information is not lost when one of the communicating parties is busy. Any number of characters can be sent, and the transmitter will automatically re-trigger with each new character (or in many cases a "bit-oriented" timing scheme is used in conjunction with network biasing for fully automatic operation, including any Baud rate and/or any communications specification, eg.