Revision 1.7 Page 9 of 27
09/12/1999
/* This will read a byte of data from a slave previously addressed */
/* by and with acknowledge already disabled by sendaddress. */
/* After reading the data, acknowledge will be re-enabled. */
5.1.5. Write Data Byte to Slave Routine
Name: writebyte(base, data)
Usage: writebyte(base, data)
Function: procedure to write a byte of data to a slave device whose slave address has
already been sent by sendaddress.
Parameters are:
int base The base address of the I2C Communications Adapter set by links on circuit
board.
int data The byte of data which is to be written to the slave device.
Value Returned:none.
I2C status on exit from routine:
The status of the I2C Communications Adapter will be 0x00 - bus busy and data
in the data register transmitted successfully. (See Appendix A for details of
Status Codes).
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, data;
base = 0x310; /* Adapter’s base address = 0 x 310- (hex) */
data = 0x69; /* Data byte which is to be transmitted */
writebyte (base, data) ;
printf(“Data has been transmitted\n”);
}
/* This will write a byte of data to a slave previously addressed */
/* by sendaddress. */
5.1.6. Send an I2C Stop Routine
Name: sendstop(controladdress)
Usage: sendstop(controladdress);
Function: procedure to send a stop (end of communication signal) down the I2C Bus,
ending a transmission or reception with a slave which was addressed previously
by sendaddress.
Parameters are:
int controladdress the address of the I2C Communications Adapter control register, equal to
1+(base address set by links on circuit board).
Value Returned:none.
I2C status on exit from routines:
The status of the I2C/ the Communications Adapter will be 0x81 - bus idle and no
unread/untransmitted data in the data register. Note - this may not be the case in
a system where there is another master as well as the I2C Communications
Adapter, since this other master may well have taken control of the bus by the
time a program next uses getstatus to read the status register. (See Appendix A
for details of Status Codes).
Example Usage: (see also sample programs)
#include <stdio.h>