Appendix B

HP E1459A Register Definitions

Overview

The HP E1459A Isolated Digital Input/Interrupt module is a register-based slave device. There are 64 isolated inputs which can be used for detecting rising and/or falling edges independently. Each 16 channels has a set of registers used to define the detection of interrupt conditions. Listed below are the different register types on this module.

•ID Register - Identifies Hewlett-Packard as the manufacturer, and that the card is an A16 register based device.

•Device Type Register - Identifies card as a HP E1459A.

•Status/Control Register - When read it returns device specific status information. When written it to, it sets control bits. Bit 4 specifies the registers for the upper or lower 32 channels.

•Edge Interrupt Status Register - This register indicates which Port has detected an edge interrupt.

•Data Available Status Register (DAV) - This register indicates which register has been externally triggered and has data available.

•Watchdog Timer Control/Status Register - The watchdog timer on the module is enabled and pet using this register.

•Command Register - There are two of these registers, each controls two ports; used to control triggering and enabling interrupts.

•Channel Data Register - There are four of these registers, one for each port; these registers contain the current channel data.

•Positive Edge Detect Register - There are four of these registers, one for each port; used to capture transitions from low to high levels.

•Negative Edge Detect Register - There are four of these registers, one for each port; used to capture transitions from high to low levels.

•Positive Mask Register - There are four of these registers, one for each port; these registers enable data to be captured in the Positive Edge Detect Registers.

•Negative Mask Register - There are four of these registers, one for each port; these registers enable data to be captured in the Negative Edge Detect Registers.

•Debounce Clock Register - There are two of these registers, one for the lower two ports and one for the upper two ports. These registers control the clock speed of the debouncers.

HP E1459A Register Definitions 75