CLRC632 Datasheet, PDF (81/163 Pages) NXP Semiconductors – Multiple Protocol Contactless Reader IC

Philips Semiconductors
Multiple Protocol Contactless Reader IC
Product Specification Rev. 3.0; May 2003
CL RC632
7.3 Controlling the FIFO-Buffer
Besides writing to and reading from the FIFO-buffer, the FIFO-buffer pointers might be reset by setting the bit
FlushFIFO. Consequently, FIFOLength becomes zero, FIFOOvfl is cleared, the actually stored bytes are not
accessible anymore and the FIFO-buffer can be filled with another 64 bytes again.
7.4 Status Information about the FIFO-Buffer
The µ-Processor may obtain the following data about the FIFO-buffers status:
• Number of bytes already stored in the FIFO-buffer: FIFOLength
• Warning, that the FIFO-buffer is quite full: HiAlert
• Warning, that the FIFO-buffer is quite empty: LoAlert
• Indication, that bytes were written to the FIFO-buffer although it was already full: FIFOOvfl
FIFOOvfl can be cleared only by setting bit FlushFIFO.
The CL RC632 can generate an interrupt signal
• If LoAlertIRq is set to 1 it will activate Pin IRQ when LoAlert changes to 1.
• If HiAlertIRq is set to 1 it will activate Pin IRQ when HiAlert changes to 1.
The flag HiAlert is set to 1 if only WaterLevel bytes or less can be stored in the FIFO-buffer. It is generated
by the following equation:
HiAlert = (64 − FIFOLength) ≤ WaterLevel
The flag LoAlert is set to 1 if WaterLevel bytes or less are actually stored in the FIFO-buffer. It is generated
by the following equation:
LoAlert = FIFOLength ≤ WaterLevel
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