If you ever need to optically isolate the I2C bus:
attached is a working schematic.
It works at up to 400 kHz
Printable View
If you ever need to optically isolate the I2C bus:
attached is a working schematic.
It works at up to 400 kHz
Attachment doesn't work.
If the GIF file does not open, right-click on it and save it.
To open the GIF file use the tool Imaging for Windows which is
part of Windows 2000 or another similar tool.
Windows 2000:
Start-Programs-Accessories-Imaging
Luciano
If the INT PIC will always act as the master, then only 3 optos are required.
The opto connected to pin 6 of P82B96 can be left out, and pin 6
is then connected to 5v. The clock signal does not need to be bidirectional
unless the EXT units must act as master.
I think, the SCL-signal is also bidirectional, because the slave-device holds down the SCL-signal in order to strecht the read-command until it is freed by the interruptprocess after filling the SSPBUF.
If you use slave devices that do NOT support clock pulse stretching
then you can eliminate one of the optos
see Philips appnote AN255_2
pg 45
http://www.semiconductors.philips.co...es/AN255_2.pdf
It appears that clock stretching in pbp can be implimented with a define
statement "DEFINE I2C_HOLD 1"