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Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
This ADC Tibbit is based on the LTC2309 12-bit ADC with I2C interface. The Tibbit
uses only four channels of this ADC. The analog front end of the module allows you
to measure signals in the -10V to +10V range. All measurements are relative to the
system ground.
Keep in mind that every time you read data out of the LTC2309 IC you are actually
getting the previous conversion result. This may not be an issue when running a
conversion loop for a single ADC channel. You will have to ignore the first result in
these cases:
·
Discard the first ADC result after the channel change. Only the second
measurement will bring you the conversion data for the newly selected channel.
·
Do the conversion twice and discard the first result when performing sporadic
measurements. This way you will obtain the "current" data.
The LTC2309 ADC IC has 12-bit resolution. Tibbit #13 has an effective resolution of
about 9 to 10 bits. This reduction is caused by system noise and other factors that
affect measurement quality.
Combine this Tibbit with
(DB9M connector). It's
not common but possible to use the latter for wiring into the ADC inputs.
Tibbit
(four terminal blocks) can also be used, but you will have to steal the
ground elsewhere, as #21 doesn't have its own ground line and the ADC measures
input voltages relative to the system ground.
LEDs
There is one red and one yellow LED. The red LED is connected to the SCL line of
the I2C interface, the yellow LED -- to the SDA line.
Sample project
The use of this Tibbit is illustrated by a Tibbo BASIC test project. You can find it
here:
https://github.com/tibbotech/CA-Test-Tibbits-13-14
7.2.9.25
#14, M1S: Four-channel DAC
Function:
Four-channel DAC
Category:
Output module
Special needs:
---
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:
See also: