Chapter 4 Register-Level Programming
© National Instruments Corporation 4-33 Lab-NB User Manual
Interrupt Status Register
The Interrupt Status Register indicates the status of the Interrupt Control Register bits and the
interrupt lines.
Address: Base address + 1 0000 (hex)
Type: Read-only
Word Size: 8-bit
Bit Map:
76543210
X X INT TIMERUP *PAINTEN *PBINTEN *TMRINTEN *ADCINTEN
Bit Name Description
7, 6 X Don’t care bits.
5 INT Interrupt Bit—This bit shows the overall state of interrupts
generated by the Lab-NB board. If this bit is set, the Lab-NB is
asserting an interrupt that has not yet been serviced. If this bit is
cleared, no interrupt is pending. This bit is normally cleared. As
explained in the description of the Interrupt Control Register
earlier in this chapter, there are four possible sources for an
interrupt.
4 TIMERUP TMRINTEN Interrupt Status Bit—This bit indicates the status of
the TMRINTEN interrupt. If this bit is set and TMRINTEN has
been set, the current interrupt is due to a rising edge on
EXTUPDATE* or counter A2's output. TIMERUP is cleared by
writing to the Timer Interrupt Clear Register or writing to either
DAC0 or DAC1. TIMERUP is set whenever a rising edge on
counter A2’s output or EXTUPDATE* is detected. TIMERUP
generates an interrupt request if it is set and the TMRINTEN bit is
set in the Interrupt Control Register.
3 *PAINTEN Port A Interrupt Enable—This bit indicates the status of the
PAINTEN bit in the Interrupt Control Register. Notice that the
polarity is reversed in the Interrupt Status Register.
2 *PBINTEN Port B Interrupt Enable—This bit indicates the status of the
PBINTEN bit in the Interrupt Control Register. Notice that the
polarity is reversed in the Interrupt Status Register.
1 *TMRINTEN Active Low TMRINTEN Interrupt Status Bit—This bit indicates
the status of the TMRINTEN bit in the Interrupt Control Register.
Notice that the polarity is reversed in the Interrupt Status Register.
0 *ADCINTEN ADCINTEN Status Bit—This bit indicates the status of the
ADCINTEN bit in the Interrupt Control Register. Notice that the
polarity is reversed in the Interrupt Status Register.