Calibre UK ICA93LV

Revision 1.7 Page 12 of 27

09/12/1999

baseaddr% = &h310 ‘* adapter’s base address = 0x310 (hex) *

controladdress% = baseaddr% + 1

status% = FNgetstatus%(controladdress%)

print”I2C Communications Adapter Status = “;status%

‘* This will read the I2C Communications Adapter’s current status *

5.2.3. I2C Address and Start Sending Routine

Name: sendaddress(baseaddr%, slv%, setnack%)

Usage: call sendaddress(baseaddr%, slv%, setnack%)

Function: procedure to send Start and slave address of device that is to be communicated

with.

Parameters are:

baseaddr% the base address of the I2C Communications Adapter set by links on circuit

board.

slv% the slave address of the device which is to be communicated with. This will be an

even number if the adapter is to write to the slave, add 1 to get an odd number if

the adapter is to read from the slave.

setnack% this controls whether the I2C Communications Adapter transmits an

Acknowledge down the I2C Bus on reception of a byte. The last byte received

during a transfer must not be acknowledged, in all other cases acknowledge

must be enabled. If setnack% = 0 then acknowledge must be enabled, if

setnack% = 1 then acknowledge is disabled. Therefore, if a read (odd number ed)

address is being sent AND only 1 byte is to be read, setnack% should be set to =

1; in all other cases it must be set = 0.

Value Returned:none.

I2C Status on exit from routine:

The status of the I2C Communications Adapter will be either &h00 - bus busy and

unread data in data register or &h80 - bus busy and no unread data in data

Appendix A for details of status codes).

Example Usage: (see also sample programs)

$include “i2c.inc” ‘* This contains the I2C routines*

baseaddr% = &h310 ‘* Adapter’s base address = 0x310 (hex) *

slv% = &ha0 ‘* IC Address of slave, this is a typical write *

‘* address for an I2C static RAM or EEPROM *

setnack% = 0 ‘* Enable Acknowledge (see parameter descriptions) *

call sendaddress (baseaddr%, slv%, setnack%)

print”Start and I2C Slave Address sent”

‘* This will send a Start and the I2C Slave Address of the device to be communicated with. *

5.2.4. I2C Read Data Byte from Slave Routine

Name: FNreadbyte%(baseaddr%, setnack%)

Usage: databyte% = FNreadbyte%(baseaddr%, setnack%)

Function: function to read a byte of data from a slave device whose slave address has

already been sent by sendaddress. Can be used to disable acknowledge after

reading data if it is the last but one byte to be read.

Parameters are:

baseaddr% the base address of the I2C Communications Adapter set by links on c ircuit

board.