Choosing I2C master or slave at runtime

Ringo42 · Joined: 07 May 2004 Posts: 263

Is it possible to set I2C master or slave at runtime?
Can I say?
if(x)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x50)
else
#use i2c(Master, SDA=PIN_C4, SCL=PIN_C3, address=0x50)

I've tried this sort of thing using the Baud rate for a Use232 command and it would not work, but then I found out how to change the baud rate on the fly. Is there something similar for I2C? I want to have several identical boards and a jumper so that when the board boots it looks at the jumper and decides if it is master or slave.

Thanks
Ringo
_________________
Ringo Davis

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

The library code isn't re-configurable between Master or Slave mode
at runtime.

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

I've never tried this but it might be possible to set them up as a Multi-Master system. Each one would be able to take turns as a master. I'm not sure, however, if they would be able to act as a Slave when they're not acting as a master. Opinions anybody???

Ronald

Edit:

I'm wondering if you would be able to manipulate bits SSPM<3:0> in the SSPCON register to switch between Master and Slave modes.