Is this problem already solved?

It seems to be a mistake in the sample program.

Although, the variable 'count' in the function i2c_transmit() should be global, it is interpreted as local.

I modified the function i2c_on_transmit() as follows:

def i2c_on_transmit ():
    global count
    count = count + 1
    print ("on_transmit, send:", count)
    return count

Then, it worked well.

Is this problem already solved?

I encountered the same problem and found a solution.
I think this is a mistake in the sample program.

Although the variable `count' in the function i2c_on_transmit must be global it is interpreted as a local variable.

I have modified the i2c_on_transmit() as follows.

def i2c_on_transmit()
  global count
  count = count + 1
  print ("on_transmit, send:", count)
  return count

Then, it worked well.