ComputerVoltageSources

--- In ComputerVoltageSources@yahoogroups.com, "Grant Richter" 
<grichter@...> wrote:
> 1. Are you using the hardware I2C pins on the PSIM?

I am using the I2C pins on the PSIM.  However, the I2COut command for 
the AtomPro24 does not use the H8 hardware.  BasicMicro did a software 
implementation of I2C protocol (I called and talked with them).  It 
will use any two pins specified in the command. I looked at the H8 
documentation to interface directly to the I2C hardware but decided it 
could be slower than using the I2Cout command.  I am able to transmit 
a byte in ~220 uS using I2COut.  That's not much time to control the 
hardware registers using Basic.  I figured it would be a performance 
wash at best and more complex coding.
 
> 2. The PSIM I2C port has the pullup resistors going to ground
> instead of +5v, did you fix this?

The resistors are not installed on my PSIM board.  My schematic shows 
them connected to +5 but it doesn't matter since they're not 
installed.
 
> 3. If you did not fix the resistors, then the I2C port is not open
> collector (drain) but is using the "hard" pullups on the GPIO
> section of the pin driver. That means only 1 device can be on the
> I2C bus?

The I2COut command appears to set the pins selected to open drain.  I 
know this because everything was hung until I added external pullup 
resistors.  It is operating in an open drain configuration.  Once I 
added 3' of cable to reach my bench, I can 'really' tell that it's 
operating with passive pullups.

Dave