PIPRS4-2

4xRS232 +48 digital I/0

Description

For users who need a higher level of integration than our standard products deliver, we offer this two-in-one board with 4 RS-232 serial ports, 48 digital I/O lines, and extended temperature operation.(Emerald-MM-DIO)

Each serial port provides the standard set of PC serial port signals. The ST16C554 quad UART chip on board contains a 16-byte FIFO for each port and supports data rates of up to 115kbps. Interrupt sharing is fully supported among the four serial ports, and an interrupt status register enables the board to operate under Windows NT. Eight different address combinations are possible, and any of 11 different interrupt levels can be used.

The 48 digital I/O lines feature programmable direction on a line by line basis, and all lines have 10KOhms pull-up resistors. One group of 24 lines includes the additional feature of programmable edge detection. Both active line selection and edge polarity are programmable. Status registers indicate which, if any, lines have changed logic levels in the selected manner since the last status check. An interrupt can be generated on the PC/104 bus whenever the indicated activity occurs.

Edge Detection Feature

The 24 digital I/O lines on ports 0 - 2 have edge detection capability. Active lines and edge polarity (rising or falling edges) are selectable line by line. When a selected line changes in the selected direction, a corresponding bit is set in an edge detection register. The 24 bits in these detection registers can be read and cleared by software. They are also funneled into an interrupt circuit, so that interrupts can be generated on the PC/104 bus when a change of state occurs.

Interrupt Status Register

The interrupt status register indicates the status of each port's interrupt request line. This register is required for proper operation under Windows NT. The status register will operate regardless of whether interrupt sharing is enabled. If two or more ports are sharing the same interrupt level, the status register will still indicate the correct status of each port's interrupt request line.

Interrupt Sharing

Each serial port requires an interrupt line for proper operation. Since there are a limited number of interrupts on the PC/104 bus, using multiple serial ports on a single computer can quickly become a problem. For this reason Emerald-MM-DIO fully supports interrupt sharing, using tristate bus drivers and a status register to indicate the interrupt status of each port. Any number of ports or boards can share the same interrupt level.

I/O Headers

Emerald-DIO contains four I/O headers: Two 20-pin I/O headers for the serial ports, with 2 ports per header, and two 50-pin headers for the digital I/O.

Specifications

Information contained in this document is subject to change without notice.
Other products and companies referred to herein are trademarks or registered trademarks of their respective companies or mark holders.