Acceleration Monitor PCB (AMP)

By: Cihad Khaled. KiCad Files

Background

The AMP tracks acceleration in the x, y, and z-axis in units of Earth's gravitational acceleration (g).

Design

The PCB is powered via a USB connection, which supplies both power and data communication to the computer. An MPU6050 tracks acceleration, which is read by an RP2040 microcontroller over an I²C interface. The computer receives this data and displays it in a console. A 1x2 connector allows the AMP to enter BOOTSEL mode when shorted. Additionally, a crystal oscillator provides a stable clock signal for timing operations.

The AMP was designed using KiCad:

Schematics Design

Figure 1.0

PCB Design

Figure 1.1

3D Rendering of AMP

Figure 1.2

Hardware

All parts were bought and put together by JLCPCB. Table 2.0 has a list of all the components used in the AMP.

Table 2.0

Physical PCB

The board arrived, and in Figure 3.1, the 1x2 connector is shorted using the red wire, thus in BOOTSEL mode.

AMP

Figure 3.0

BOOTSEL Mode

Figure 3.1

Software

The software was programmed in MicroPython and uploaded to the RP2040's file system. The software configures the I²C interface by connecting the RP2040's GPIO28 and GPIO29 to the SDA and SCL of the MPU6050. The MPU6050 has a standardized address that the RP2040 communicates with to wake it up and start collecting acceleration data from the AMP.

Code uploaded onto the AMP

Figure 4.0

Output

The code displays the data from the AMP onto the console, showing the x, y, and z components of the acceleration in units of g.

Stationary

When the AMP is placed stationary and upright, the z component represents the Earth's gravity on the AMP (~1g = 9.8 m/s²), while x and y are close to zero g. Shown in Figure 4.1, there is a slight discrepancy due to the AMP not being perfectly upright, causing Earth's gravity to also appear in the x and y components. Additionally, some noise is present in the readings.

Figure 4.1

AMP says WOOF!

The AMP was getting antsy staying stationary, so it went on a walk in the negative y direction while slowly increasing speed, as shown in Figure 4.2.

Figure 4.2

AMP goes up, up, up... and back down?

The AMP being thrown into the air was simulated (no broken PCB today!). The z-axis shows the acceleration of it going up and then coming back down, as shown in Figure 4.3.

Figure 4.3

"Around we go"

The AMP was swung around in a circle, and the y-axis represents the centripetal acceleration of the PCB, as shown in Figure 4.4. The centripetal acceleration could be used to calculate the tension of the wire connecting the computer and the AMP.

Figure 4.4

Challenges

The AMP project was a difficult PCB to make with zero experience. Understanding how each chip interacted with the others was challenging, and extracting relevant information from datasheets was a struggle in itself. Learning how to read and interpret datasheets is a skill I need to continue developing if I want to keep making PCBs.