Processing of both the
transmitter and receiver functions is performed in interrupt service routines, whereby the
processor falls into an idle mode if no interrupts need to be serviced.
5.2.9.1 Device Drivers
A software module that controls how a processor communicates with a device is called a
device driver. In SDLR, the interface from the DSP ?¬?rmware to the hardware is abstracted
into a set of device drivers. The device drivers separate the high-level ?¬?rmware and
protocol-speci?¬?c modules from the low-level input=output (IO) routines of hardware.
Device drivers are provided for each of RF??™s transmit and receive modules as well as for
actuators and sensors.
Contemporary RFID Reader Architecture 105
SDLR uses a special abstraction to access device registers independent of the underlying
implementation. It hides the mechanisms to access a speci?¬?c part of the address
spaces. The use of this abstraction is in almost all cases as ef?¬?cient as an assembly
language access. These device drivers are designed to provide access to the hardware in
a protocol-independent manner that allows the change of communication protocol without
the need of changing the rewriting low-level subroutines. The device driver application
program interface (API) is a set of C callable functions for writing to or reading from
the device or registers. This API is based on the POSIX ?¬?le IO interface, using read,
write, and ioctl functions.
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