User Manual

5.3 Analog Inputs

There are 8 pins that can be configured as analog inputs. Refer to Table 4-2

for the specific I/O pin capabilities.

Using the analog input pins consists of the following:

Configuring the pins

Select direction as analog input. Select the analog-to-digital

converter settings for each specific pin configured as an analog input

(refer to Section 4.2.7).

Configuring the sleep state of the pins

Select direction (input or output), enable or disable pull-up or pull-

down resistors for pins configured as digital inputs, and set the

output value for pins configured as digital outputs. Note that pins

configured as analog inputs under normal operating mode can be set

as anything when the Matrix module is put into Sleep Mode.

Reading the state of the pins configured as analog inputs

Read the analog value of the signal applied to the pins configured as

inputs.

The voltage on the analog input pins is determined by the following

equations. These equations take into account the “reference

voltage” and “resolution” from the “Analog Input ADC Settings”. The

“Analog Input ADC Settings” can be set and queried from the module

using host messages 0x25 (Set Analog Input ADC Settings) and

0x26 (Query Analog Input ADC Settings).

8 Bit Resolution

Analog Input Voltage = (Analog Value / 128) x Reference Voltage

10 Bit Resolution

Analog Input Voltage = (Analog Value / 512) x Reference Voltage

12 Bit Resolution

Analog Input Voltage = (Analog Value / 2048) x Reference Voltage

14 Bit Resolution

Analog Input Voltage = (Analog Value / 8192) x Reference Voltage