Thomas.DeVito 1.21.2011


  • Spent most of the day switching and setting up the printer for people
  • I could not find the hp solution center software for windows 7.  This is needed to set a destination for easy scanning


  • Still looking for a good chip to control the gain on our amplifier chip
  • I2C needs to have a 1k resistor connecting each signal to 5v coming from the usb-i2c adapter.  This is called a pull-up resistor not sure why its needed.  Pull-up is when you connect something to the high side, pull down is when you connect something to the low-side or gnd.
  • So far I have found big chips with large resistances and tiny chip with good resistance range.  I am leaning towards a 14 pin tssop package which will need an adapter(tiny but at least proto advantage sells the adapters).  The optimal resistance of the i2c variable potentiometer is 5k ohm  which will be in series with another 5k ohm fixed resistor.  The reason 5k is the target rating is because the mechanical variable pot we have has a maximum for 1ok.  The max volume we want happens around 7680 which is approximately half of the maximum resistance of the variable pot in series with a 5k resistor.  Each step in a 7bit(128 step) 5k variable pot is each to about 40 ohm, which means we have roughly 36 steps of control over the volume range we want to use.  Most of the chips I am looking at have dual potentiometers which means we will only need 3 to control 5 fingers.
  • Tried putting a resistor between the + side of the amp output and the speaker to see if anything good would happen due to confusion of how one of the ICs worked.  Nope nothing good happened as expected so I must have been misreading tat ones documentation.