MCP4261 as logarithmic potentiometer

   In previous article, I tested my MCP4261-502E/P dual digital potentiometer, now I show you how can use this dual potentiometer for audio (volume control), for that must change liniar characteristic to logarithmic characteristic (or like this).
   So, I use info from article Controlling Volume - log pots publish on TEXAS INSTRUMENS's site.
   

   For simple sketch and for not use more resource, I use log aproxximation, so I calculate the equations for each straights:

- for first, from 0 to 63%: y = x/5 (I know x=0 -> y=0 & x=50 -> y=10)

- for second, from 63 to 100%: y = 7/3 * x - 400/3 (I know x=70 y=30 & x=100 -> y=100)

  I use same schematic like in previous article:

and I write a sketch for test more cases, this sketch is MCP4261_lin_to_log_1.ino .

  I made 2 movies:

- MCP4261 as logarithmic pot using Arduino

- MCP4261 as logarithmic pot using Arduino (2)

  For digital potentiometer with 16 steps + mute, I have next cases:

   Centralizing, we see some errors but for me there are acceptable:

and I cat continue experiments for implements this digital potentiometer in future audio project..

MCP4261 dual digital potentiometer

   I have an MCP4261-503E/P dual digital potentiometer hwo can control via SPI interface in 256 steps (0 to 255 - 8 bits).

   I use info find in article Arduino - Using digital potentiometers part 2 (MCP4251) from Matthew McMillan's blog.
   My digital potentiometer is in THT/PDIP capsule:

   After info from Mattew's sketch I made my test schematic:

and after made some changes, I upload MCP4261_mega_lcd1602_i2c_test.ino sketch.

   For tests, I have some particular cases:

- both on minimum 

- first potentiomer at minimum and second at maximum:

- first potentimeter at maximum and second at minumum value:

- both at maximum:

and after that I put to change steps from 0 to 255 to see the difference between potentiometers:

   I put on net 2 movies:

-  MCP4261 digital dual potentiometer with Arduino Mega:

- MCP4261 digital dual potentiometer with Arduino Mega (2)