#14, M1S: Four-Channel DAC

Function: Four-channel DAC

Form factor: M1S

Category: Output module

Special needs: +15V and -15V power (use Tibbit #12 to generate these voltages)

Power requirements: 5V/20mA, 15V/4mA, –15V/4mA (the aggregated consumption through Tibbit #12 is 56mA, measurements were made with no loads on the DAC outputs)

Mates with: #19, #20, #21 (limited use)

See also: #13

Details

This digital-to-analog converter (DAC) Tibbit is based on the MCP4728 12-bit DAC with an I²C interface. The Tibbit uses all four channels of this DAC . The analog front end of the module allows you to output signals in the –10V to +10V range (respective to the system ground).

The MCP4728 DAC IC has a 12-bit resolution. Tibbit #14 has an effective resolution of about 9~10 bits. This reduction is caused by system noise and other factors that affect measurement quality.

Combine Tibbit #14 with #20 (nine terminal blocks) or #19 (DB9M connector). It's possible, but not common, to use the latter for wiring into the DAC outputs. Tibbit #21 (four terminal blocks) can also be used, but you will have to steal the ground from elsewhere, as #21 doesn't have its own ground line and the DAC outputs voltages with respect to the system ground.  

LEDs

There are two red, one yellow, and one green LED. The red LEDs are connected to the SCL and –LOAD lines, the yellow LED to the SDA line, and the green LED to the –BUSY line.

Sample Project

The use of Tibbit #14 is illustrated by a Tibbo BASIC test project. You can find it here: https://github.com/tibbotech/CA-Test-Tibbits-13-14.