Sunday, August 10, 2014

Si570 shield progress

I have spent some time today working on my Si570 Arduino shield.  A few changes:
  1. Added a 3.3V regulator on the board with a separate power input (9-12v) as with dual Si570 devices on the board, I don't want to draw that current from the Arduino regulator.
  2. Increased the trace size for the 3V3 power rail off the regulator.
  3. Changed the SMA connector footprint to be appropriate for a much more narrow connector.
  4. I2C multiplexor chip used to drive multiple (up to 4) I2C buses optionally at different logic levels.  I drive the multiplexor at 5V from the Arduino.  Each Si570 is on its own 3V3 bus and two extra busses are available.  I included the 3V3 OLED display on the first Si570 bus.
  5. Hand routing of the mess made by the Eagle auto-router.
To be done:
  1. Replace reset button with one that is actually available.
  2. Rework the SMA connector footprint a little more as it is still marginally too wide.
A lot of discussion was passed back and forth regarding the use of separate connections for the various periphery that will connect this shield to the Minima board.  Most folks suggested that I just use the normal Arduino connectors along the edges for all off-board connections.  I have provided those connections for those that choose to connect in this way or decide to stack another shield on top of the Si570 shield.

I however also included individual connections for individual periphery (encoder, paddles, buttons, PTT, etc.) so that a cable with a ground and signal lines can be connected as a single connector without having to worry about multiplexing ground lines, etc.

Using the I2C multiplexor will require a change to my Si570 driver and OLED driver.  5V I2C displays will not require any code changes as they will be connected directly to the 5V Arduino I2C bus.

Here is a quick screen shot of the board.  It is pretty close to being ready to send off the be manufactured.



I am hoping to get these off to be created this week.

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