SLRC400 Datasheet, PDF (69/130 Pages) NXP Semiconductors – I·CODE Reader IC

Philips Semiconductors
I•CODE Reader IC
Product Specification Rev. 2.0 November 2001
SL RC400
8 INTERRUPT REQUEST SYSTEM
8.1 Overview
The SL RC400 indicates certain events by setting bit IRq in the PrimaryStatus-Register and, in addition, by
activating pin IRQ. The signal on pin IRQ may be used to interrupt the µ-Processor using its interrupt
handling capabilities. This allows the implementation of efficient µ-Processor software.
8.1.1 INTERRUPT SOURCES OVERVIEW
The following table shows the integrated interrupt flags, the related source and the condition for its setting.
The interrupt flag TimerIRq indicates an interrupt set by the timer unit. The setting is done when the timer
decrements from 1 either down to zero (TAutoRestart flag disabled) or to the TPreLoad value if TAutoRestart
is enabled.
The TxIRq bit indicates interrupts from different sources. If the transmitter is active and the state changes
from sending data to transmitting the end of frame pattern, the transmitter unit sets automatically the interrupt
bit. The CRC coprocessor sets TxIRq after having processed all data from the FIFO buffer. This is indicated
by the flag CRCReady = 1. If the E²Prom programming has finished the TxIRq bit is set, indicated by the bit
E2Ready = 1.
The RxIRq flag indicates an interrupt when the end of the received data is detected.
The flag IdleIRq is set if a command finishes and the content of the command register changes to idle.
The flag HiAlertIRq is set to 1 if the HiAlert bit is set to one, that means the FIFO buffer has reached the level
indicated by the bit WaterLevel, see chapter 7.4.
The flag LoAlertIRq is set to 1 if the LoAlert bit is set to one, that means the FIFO buffer has reached the
level indicated by the bit WaterLevel, see chapter 7.4.
Interrupt Flag
TimerIRq
TxIRq
RxIRq
IdleIRq
HiAlertIRq
LoAlertIRq
Interrupt Source
Timer Unit
Transmitter
CRC-Coprocessor
Receiver
Command Register
FIFO-buffer
FIFO-buffer
Is set automatically, when
the timer counts from 1 to 0
a data stream, transmitted to the label, ends
all data from the FIFO buffer has been processed
a data stream, received from the label, ends
a command execution finishes
the FIFO-buffer is getting full
the FIFO-buffer is getting empty
Table 8-1: Interrupt Sources
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Preliminary