Connecting Digital and Analog Inputs to AMFITRACK Sensors¶
This guide explains how to connect external digital and analog inputs to the AMFITRACK sensors, ensuring proper configuration and operation.
Prerequisites¶
Compatible Device: AMFITRACK G3 device (firmware version 3.2.0.3 or later).
The AMFITRACK sensor provides 4 digital inputs and 1 analog input. The inputs are located on various parts of the PCB, including test points, connectors, and the USB connector. These will be detailed in the following sections.
Digital Inputs¶
The AMFITRACK sensor includes 4 digital inputs. These are open-drain inputs with internal pull-up resistors. By default, the inputs are measured as “high” (logic 1) when unconnected. Users can pull the inputs “low” (logic 0) to register a change.
The digital inputs are represented as the first 4 bits of a 16-bit value in the sensor’s data package (GPIO_State). Each bit corresponds to a specific digital input:
Bit 0: Digital Input #1
Bit 1: Digital Input #2
Bit 2: Digital Input #3
Bit 3: Digital Input #4
Digital Input #1¶
Location: J5 connector, Pin 7 (front side of the PCB, below the battery).
Digital Input #2¶
Location: J5 connector, Pin 8 (front side of the PCB, below the battery).
Digital Input #3¶
Location: Test Point TP24 (refer to Figure 1 and Figure 2).
Digital Input #4¶
Location: Test Point TP23 (refer to Figure 1 and Figure 2).
Analog Input¶
The AMFITRACK sensor features a single analog input with a 12-bit resolution, capable of measuring voltages within the range of 0.000 V to 4.095 V. However, the hardware limits the input voltage to a maximum of 3.000 V. While the full digital range (0–4095) maps to 0.000 V–4.095 V, any voltage above 3.000 V will exceed the sensor’s supported range and may cause damage.
The analog input is represented as the last 12 bits of a 16-bit value in the sensor’s data package (GPIO_State). This allows precise measurement of the analog signal while sharing the data package with the 4 digital inputs, which occupy the first 4 bits.
The relationship between input voltage and the digital value is as follows:
0 (digital value): Corresponds to 0.000 V.
4095 (digital value): Corresponds to 4.095 V.
Note
Although the digital resolution supports up to 4.095 V, ensure the analog input voltage does not exceed 3.000 V to avoid potential damage to the device.
Access Points¶
The analog input can be accessed at the following locations:
Test Point TP1: Located on the PCB (refer to Figure 1 and Figure 2).
SBU Pin 1: Found in the USB connector.
Sensor G3 V1.00 -> V1.02¶
Figure 1: Picture of the back side of the AMFITRACK sensor G3 V1.01¶
Sensor G3 V2.1¶
Figure 2: Picture of the back side of the AMFITRACK sensor G3 V2.10¶
Contact Support¶
For further assistance, contact us at support@amfitrack.com.