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mcp472 [2019/03/31 14:50]
mcp472 [2019/03/31 14:50] (current)
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 +====== MCP4725 ======
 +
 +The MCP4725 is a 12 bit digital to analog converter and can be powered from 2.7
 +to 5.5 volts. Datasheet [[https://cdn-shop.adafruit.com/datasheets/mcp4725.pdf|link]].
 +
 +It is very simple to use. It has a 7 bit addressing scheme with a 3 bits that are
 +variable and called A0, A1 and A2. A2 and A1 are chosen at the order process and are
 +selected by selecting part numbers. A0 is broken out to a pin and is to be tied
 +either to GND or to VDD. On the adafruit board it is pulled low and also broken out. 
 +
 +The ID of the standard chip with A0 pulled low. is ''%%0x62%%''. ''%%0x62%%'' is the first 7 bits of
 +the first byte we send out, which comes out to ''%%0b1100010%%''. When we tack on the R/W bit
 +as the LSBit this comes to:
 +
 +<code>
 +0b11000100 or 0xC4 for Write
 +0b11000101 or 0xC5 for Read
 +</code>
 +
 +Writes to set the output of this chip are done as a 12bit values which range from
 +''%%0x000%%'' which is ''%%0%%'' to ''%%0xFFF%%'' which is VDD - 1LSB. 
 +
 +This chip has a bunch of fancy features such as power down modes for low power and
 +EEPROM to store output values. We don't need to use any of this stuff and just want
 +to use the fast mode and 0 for the power down vales. This makes the chip behave just
 +as we want it, output an analog signal when we tell it to!
 +
 +To do this, write the following:
 +
 +<code>
 +0xC4, 0x0P 0xQR 
 +</code>
 +
 +PQR are is the hex value from ''%%0x000%%'' to ''%%0xFFF%%'' of the analog output we want.
 +
 +To do this in the bust pirate, just set the thing up in [[I2C]], turn on the 5 volt rail
 +(its OK to do this, the device will talk to the chip just fine) and send out the
 +following:
 +
 +<code>
 +[0xC4 0x0P 0xQR]
 +</code>
 +
 +with PQR the number we want to send out. 
  
  • mcp472.txt
  • Last modified: 2019/03/31 14:50
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