setnack% | this controls whether the I2C Communications Adapter transmits and |
| 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 is enabled, if setnack% = 1 |
| then acknowledge is disabled. Therefore, if the LAST BUT ONE byte is to be |
| read, setnack% should be set to =1; in all other cases it must be set = 0. (In the |
| case of reading 1 byte only, acknowledge will have been disabled by |
| sendaddress and so should now be enabled again after reading the data, hence |
| setnack% = 0 for reading a single byte of data.) |
Value Returned: |
|
<databyte%> | the function reads the byte of data and returns an integer equal to the value read. |
I2C status on exit from routine:
| The status of the I2C/ the Communications Adapter will be either &h00 - bus the | |
| busy and unread data in the data register or &h80 - bus busy and no unread data | |
| in the data register | depending on whether any more bytes of data have |
| been transmitted by the slave device which is being read. (See 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 = 310 (hex) * | |
setnack% = 0 | ‘* Enable Acknowledge - only one byte is to be read * | |
‘* (see parameter descriptions) *
databyte% = FNreadbyte%(baseaddr%, setnack%) print “Data read was “;databyte%
‘* 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
5.2.5.Write Data Byte to Slave Routine
Name: | writebyte(baseaddr%, databyte%) |
Usage: | call writebyte(baseaddr%, databyte%) |
Function: | procedure to write a byte of data to a slave device whose slave address has |
| already been sent by sendaddress. |
Parameters are: |
|
baseaddress% | the base address of the I2C Communications Adapter set by links on circuit |
| board. |
databyte% | 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 &h00 - 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 “i2c.inc” | ‘* This contains the I2C routines * |
baseaddr% = &h310 | ‘* Adapter’s base address = 310 (hex) * |
databyte% = &h69 | ‘* Data byte which is to be transmitted* |
call writebyte(baseaddr%, data byte%) print”Data has been transmitted”
‘* This will write a byte of data to a slave previously addressed by sendaddress. *
5.2.6.Send an I2C Stop Routine
Name: | sendstop(controladdress%) |
Usage: | call sendstop (controladdress%) |
Revision 1.7 | Page 13 of 27 |
09/12/1999 |
|