MCP4725 - DAC working with Pico

[espruino-discuss2]

Posted at 2015-06-12 by LawrenceGrif

Hi just to say got a MCP4725 - DAC working (thanks to some Python code form johnwhittington) on the Pico. I'm using Sparkfun module but Ada Fruit do one too.
https://www.sparkfun.com/products/12918?_ga=1.22340158.462334063.1427963564

var voltage = 4095;
var dac = [2];
voltage = (voltage > 4095) ? 4095 : voltage;

// MCP4725 expects a 12bit data stream in two bytes (2nd & 3rd of transmission)
dac[0] = (voltage >> 8) & 0xFF;    // [0 0 0 0 D12 D11 D10 D9 D8] (first bits are modes for our use 0 is fine)
dac[1] =  voltage & 0xFF;                // [D7 D6 D5 D4 D3 D2 D1 D0]

I2C1.setup({scl:b6, sda:b7, bitrate:100000});
I2C1.writeTo(0x60,[dac[0],dac[1]]);

[gfwilliams]

Posted at 2015-06-15 by @gfwilliams

Nice - and that's all that's needed? No setup code or anything?

You could actually simplify the code a bit further, because you can take advantage of the fact that I2C.writeTo takes bytes (so effectively does &0xFF for you).

var voltage = 4095;
voltage = E.clip(voltage,0,4095);
// MCP4725 expects a 12bit data stream in two bytes (right aligned)
I2C1.setup({scl:b6, sda:b7, bitrate:100000});
I2C1.writeTo(0x60,[voltage >> 8,voltage]);

It might be worth turning this into a module? It'd be tiny, but would at least make using the MCP4725 really easy for anyone who didn't want to worry about I2C commands.