Revision 1.7 Page 6 of 27
09/12/1999
5. Using the Utilities
Each utility is documented in a standard format, which lists its name, usage, function, and effect on the
adapter is given. Following a reset, the adapter should be setup prior to any data transfer.
5.1. C Routines
5.1.1. I2C Setup/Initialisation Routine
Name: setup(base, own, sclk)
Usage: setup(base, own, sclk);
Function: procedure to set up I2C Communications Adapter.
Parameters are:
int base base address of adapter set by links on circuit board.
int own I2C address to which the adapter is to respond in slave mode. This forms the
upper 7 bits of the 8 bit address; the lowest bit being the Read (1) or Write (0) bit.
This means that if own = 0x57, the card will respond to a Write to address 0xAE
and a Read to address 0xAF. Be sure not to select an address that is already in
use by any other device in your I2C system. If own = 0x00 the adapter will monitor
all I2C bus information but will not affect any data transfers, thus acting as a bus
monitor.
int sclk the SCL clock rate (bit rate for I2C serial bus).
Value of sclk Approximate SCL (kHz)
090
145
211
31.5
Value Returned:none.
I2C status on exit from routine:
The I2C Communications Adapter will have the serial interface enabled; also data
reception acknowledge will be enabled. The status register will contain 0x81
(assuming that no other masters exist on the I2C system, if this is not the case
then the contents of the status register will also depend on externally generated
bus activity).
Example Usage: (see also sample programs)
#include <stdio.h>
#include <dos.h> /*Optional, but recommended if your compiler */
/*supports DOS I/O functions */
#include <i2c.h> /*This contains the I2C routines */
main
{int base, own, sclk;
base = 0x310; /* Adapter’s base address = 0x310 (hex) */
own = 0x57; /* Own slave address set to 0x57 (hex) */
sclk = 1; /* Serial clock rate set to 45KHz */
setup(base, own sclk);
printf(“I2C Communications Adapter initialised\n”);
}
/* This will set up the I2C Communications Adapter with a base */
/* address of 0x310, an I2C slave address of 0xAE and a SCL */
/* clock rate of approximately 45KHz */
5.1.2. I2C Status Checking Routine
Name: getstatus(controladdress)
Usage: status = getstatus(controladdress);
Function: function to read status register of I2C Communications Adapter.