Revision 1.7 Page 11 of 27
09/12/1999
Name: setup (baseaddr%, own%, sclk%)
Usage: call setup(baseaddr%, own%, sclk%)
Function: procedure to set up I2C Communications Adapter.
Parameters are:
baseaddr% base address of adapter set by links on circuit board.
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% = &h57, the card will respond to a Write to address
&hAF. Be sure not to select an address that is already in use by any other device
in your I2C system. If own% &h00 the adapter will monitor all I2C bus information
but will not affect any data transfers, thus acting as a bus monitor
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 &h81
(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 “i2c.inc” ‘* This contains the I2C routines*
baseaddr% = &h310 ‘* Adapter’s base address = &h310 (hex) *
own% = &h57 ‘* Own slave address set to &h57 (hex) *
sclk% = 1 ‘* Serial clock rate set to 45KHz *
call setup(baseaddr%, own%, sclk%)
print”I2C Communications Adapter initialised”
‘* This will set up the I2C Communications Adapter with a base address *
‘* of &h310, an I2C slave address of &hAE and a SCL clock rate of *
‘* approximately 45KHz *
5.2.2. I2C Status Checking Routine
Name: FNgetstatus%(Controladdress%)
Usage: status% = FNgetstatus%(controladdress%)
Function: function to read status register of I2C Communications Adapter.
Parameters are:
controladdress% address of I2C control register. This is equal to 1+(base address of adapter set
by links on circuit board).
Value Returned:
<status%> where status is an integer from &h00 to &hFF which indicates the current status
of the I2C communications Adapter. Appendix A for details of the status values
returned.
I2C status on exit from routine:
The status of the I2C Communications Adapter will not be affected by using the
FNgetstatus% function.
Example Usage: (see also sample programs)
$include “i2c.inc” ‘* This contains the I2C routines *