SI2493-D-FS Silicon Laboratories Inc, SI2493-D-FS Datasheet - Page 292

• Manufacturer Part Number: SI2493-D-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-D-FS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN93
Software Description
Hardware Access Layer
This layer contains all the routines to access the MCU and modem hardware at the most basic level. The
application layer typically does not need to access these functions directly. It consists of two source files:


MCU_hardware.c
This sample code will work only on the Silicon Labs MCU C8051F12xx platform used for this example. This file
contains code specific to the MCU hardware configuration such as port configuration, oscillator configuration,
timers, UART, GPIOs, etc.
modem_hardware.c
This code can be ported to other applications with minimal changes needed to compile on a given host platform.
This file contains code to read from or write to the modem. The two functions below provide basic access to the
modem's Hardware Interface Registers:
char readModem( tHIRREG eHIR ) : This is the main access point for unconditionally reading the modem's
data and status registers in parallel or SPI mode. The function reads the HIR0 when eHIR is HIR0 (0) and the
HIR1 when eHIR is HIR1 (1).
void writeModem( tHIRREG eHIR, char val, char mask ) : This is the main access point for
unconditionally writing the modem's data and control registers in parallel or SPI mode. The parameter eHIR can be
HIR0 (0) or HIR1 (1). When writing to the HIR1, an optional mask value allows first reading the HIR1 from the
modem by calling readModem(), and then setting or clearing only those bits that are high in mask. Defined values
for mask are:
#define SiCTSb 0x01 // Clear to send (active low)
#define SiRTSb 0x02 // Request to send (active low)
#define SiESC
#define SiINT
#define SiINTM 0x10 // Enable software interrupt
#define SiREM
#define SiTXE
#define SiRXF
Boolean-OR combinations of the above are possible. This allows setting and/or clearing several bits
simultaneously. Thus a mask value of 0xFF results in all bits of val being written to the HIR1, and a mask value of
zero reads the HIR1 and simply rewrites the value just read, ignoring val . The mask parameter is ignored when
writing to the HIR0.
Interrupt Service and Polling Layer
Sample code for this layer can be found in the ISR_and_Polling.c file. This code can be ported to other
applications with minimal changes needed to compile on the host platform. This block contains the interrupt service
routines for both modem access and MCU to PC UART access. Except for modemCommunicationUpdate() , the
application layer typically does not need to access these functions directly. The access mode is interrupt driven by
default. In order to select polling mode, the system must set the global variable pollingNotInterruptMode to a
nonzero value. The software is designed to allow switching back and forth between polling and interrupt modes. If
only one mode is ever used, the code can be simplified accordingly. The next two sections detail out the functioning
of the polling and interrupt modes.
292
MCU_hardware.c
modem_hardware.c
0x04 // Escape to command mode
0x08 // Software interrupt
0x20 // Receive FIFO empty
0x40 // Transmit FIFO almost empty interrupt
0x80 // Receive FIFO almost full interrupt
Rev. 1.3