
CLRC632_35
NXP B.V. 2009. All rights reserved.
Product data sheet
PUBLIC
Rev. 3.5 — 10 November 2009
073935
20 of 126
NXP Semiconductors
CLRC632
Multiple protocol contactless reader IC (MIFARE/I-CODE1)
9.3.3 FIFO buffer status information
The microprocessor can get the following FIFO buffer status data:
the number of bytes stored in the FIFO buffer: bits FIFOLength[6:0]
the FIFO buffer full warning: bit HiAlert
the FIFO buffer empty warning: bit LoAlert
the FIFO buffer overow warning: bit FIFOOv.
Remark: Setting the FlushFIFO bit clears the FIFOOv bit.
The CLRC632 can generate an interrupt signal when:
bit LoAlertIRq is set to logic 1 and bit LoAlert = logic 1, pin IRQ is activated.
bit HiAlertIRq is set to logic 1 and bit HiAlert = logic 1, pin IRQ activated.
The HiAlert ag bit is set to logic 1 only when the WaterLevel[5:0] bits or less can be
stored in the FIFO buffer. The trigger is generated by
Equation 1:(1)
The LoAlert ag bit is set to logic 1 when the FIFOLevel register’s WaterLevel[5:0] bits or
less are stored in the FIFO buffer. The trigger is generated by
Equation 2:
(2)
9.3.4 FIFO buffer registers and ags
Table 18 shows the related FIFO buffer ags in alphabetic order.
9.4 Interrupt request system
The CLRC632 indicates interrupt events by setting the PrimaryStatus register bit IRq (see
on pin IRQ can be used to interrupt the microprocessor using its interrupt handling
capabilities ensuring efcient microprocessor software.
HiAlert
64
FIFOLength
–
() WaterLevel
≤
=
LoAlert
FIFOLength
WaterLevel
≤
=
Table 19.
Associated FIFO buffer registers and ags
Flags
Register name
Bit
Register address
FIFOLength[6:0]
FIFOLength
6 to 0
04h
FIFOOv
ErrorFlag
4
0Ah
FlushFIFO
Control
0
09h
HiAlert
PrimaryStatus
1
03h
HiAlertIEn
InterruptEn
1
06h
HiAlertIRq
InterruptRq
1
07h
LoAlert
PrimaryStatus
0
03h
LoAlertIEn
InterruptEn
0
06h
LoAlertIRq
InterruptRq
0
07h
WaterLevel[5:0]
FIFOLevel
5 to 0
29h