For this assignment I have to design my own PCB circuit, solder components in it and test it using the Arduino. This is the Schematic I have used in order to create my own circuit.
As part of our group assignment, we are required to test multiple devices to obtain various readings. To achieve this, I have opted to employ a multimeter to measure voltage and an oscilloscope to capture DC signals. For the purpose of our testing, I utilized the Adafruit Feather Sense nRF52480 to generate signals and provide voltage. The following code was used to generate the signal:
void setup()
{
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
}
void loop()
{
digitalWrite(12, HIGH);
digitalWrite(13, HIGH);
delayMicroseconds(100); // Approximately 10% duty cycle @ 1KHz
digitalWrite(13, LOW);
delayMicroseconds(1000 - 100);
}
To measure the voltage, I utilized the Terminator TMM7201 multimeter and configured it to measure up to 20V for reading.The output voltage listed in the datasheet for the Adafruit Feather Sense nRF52480 is likely listed as 3.3V because that is the nominal voltage that the device is designed to output. This nominal voltage is often used to simplify the description of a device's output voltage and to make it easier for users to understand the device's capabilities.
In reality, the output voltage of the device can vary slightly from the nominal voltage due to a number of factors, such as manufacturing tolerances, temperature, and load conditions. Additionally, the accuracy of the multimeter used to measure the voltage can also affect the measured value.
Therefore, a measured output voltage of 3.27V instead of the nominal 3.3V is within the expected range of variation and is unlikely to significantly affect the device's performance.
To scope the signles, I utilized the Oscilloscope 1152A-U oscilloscope and configured it to scope to 500mv for reading. There are several possible reasons why there may be noise in the output signal scoped in the Gw INSTEK Oscilloscope 1152A-U from the Adafruit Feather Sense nRF52480.
To scope the signles, I utilized the PicoScope PC Oscilloscope oscilloscope and configured it to scope to 5v for reading. To enable the display of signals on a PC, it is essential to download the PicoScope 7 software for this device.
There are several possible reasons why there may be less noise in the output signal reading on the PicoScope PC Oscilloscope compared to the Gw INSTEK Oscilloscope 1152A-U, even when both are connected to the same output signal from the Adafruit Feather Sense nRF52480.
To further investigate the issue, it may be helpful to compare the specifications of both oscilloscopes, including their input impedance, bandwidth, and signal processing capabilities. Additionally, it may be useful to check the grounding of the Gw INSTEK Oscilloscope 1152A-U and ensure that there are no ground loops or other grounding issues present.
## Individual Assigment
In this individual assigment, I will discuss my experience with downloading and utilizing Eagle software for designing PCBs and schematics, focusing on the development of a board to interact and communicate with an embedded microcontroller, specifically the Seeed Xiao NRF52840. I will outline the process of downloading and setting up Eagle software, as well as the design steps involved in creating the development board.
First, I downloaded Eagle software from the official Autodesk website and quickly set it up on my computer. With its user-friendly interface and extensive component library, Eagle proved to be an excellent choice for PCB and schematic design. I utilized the software's features to design a development board tailored to interact and communicate with the Seeed Xiao nrf52840 microcontroller.
The design process involved creating a PCB layout and schematic diagram using Eagle's intuitive tools. I carefully considered component placement, routing paths, and power distribution to ensure optimal functionality and performance. Additionally, I incorporated GPIO pins, communication interfaces (UART, SPI, I2C), and power supply circuitry to enable seamless interaction and communication with the embedded microcontroller. Overall, Eagle software provided an efficient and reliable platform for designing the development board, allowing for a successful implementation of the Seeed Xiao nrf52840 microcontroller.
Choosing an appropriate track width size, approximately 0.4mm, is crucial when designing a PCB to be milled with a machine capable of handling thinner tracks. This track width offers several advantages, including accurate milling without damaging surrounding areas and providing sufficient spacing for soldering components onto the board. It enables precise milling while accommodating intricate and compact designs. Additionally, the 0.4mm track width allows for reliable soldering, ensuring proper solder flow and strong connections between component leads and tracks. It also helps maintain optimal voltage performance by minimizing voltage drops and facilitating smooth power distribution throughout the development board designed for the Seeed Xiao NRF52840 microcontroller.
| Qty | Description |
|---|---|
| 3 | 1002 SMD Resistor |
| 2 | 0664 SMD Resistor |
| 1 | 1uf Capacitor |
| 1 | 20 MHZ Xtal |
| 1 | ATtiny 44 |
| 1 | FIDI (6 Pins) |
| 1 | ISP (6 Pins) |
| 2 | Buttons |
| 2 | LEDs |
A printed circuit board (PCB) is a laminated sandwich structure of conductive and insulating layers. PCBs have two complementary functions. The first is to affix electronic components in designated locations on the outer layers by means of soldering. The second is to provide reliable electrical connections (and also reliable open circuits) between the component's terminals in a controlled manner often referred to as PCB design. Each of the conductive layers is designed with an artwork pattern of conductors (similar to wires on a flat surface) that provides electrical connections on that conductive layer.
The machine software can read only rml file. So we required different methods to converts the file into rml format. This modes are develop by Fab Academy and it is used for all cutting machine.
The Roland SRM-20 is a next-generation desktop mill that boasts a micro-step motor drive system for clean and precise contours and a great feed rate. We can multiple materials using this machine, but for this assignment I have used copper sheets.
In PCBs, the copper sheet is laminated in the non-conductive substrate. We can say that PCB supports the communication between various parts of electrical components because it helps signals to follow the pathways. PCBs are designed in such a way that they can connect several points in electronic devices. For the signal flowing purpose, solders are used for making the connection between electronic devices and PCB surfaces. Solders are also strong mechanical adhesive because of the metal used in them.
| Qty | Description |
|---|---|
| 3 | 1002 SMD Resistor |
| 2 | 0664 SMD Resistor |
| 1 | 1uf Capacitor |
| 1 | 20 MHZ Xtal |
| 1 | ATtiny 44 |
| 1 | FIDI (6 Pins) |
| 1 | ISP (6 Pins) |
| 2 | Buttons |
| 2 | LEDs |
After cutting the PCB and prepared the components, its time for soldering. Things need to consider while soldering are:
After completing the soldering and making sure all the connection are connected correctly, I have tested my circuit with Arduino using this code. Everything was working fine, but there was delay which causes by the code setup for frequency.
void setup() {
//start serial connection
Serial.begin(9600);
//configure pin 3 as an input:
pinMode(PA3, INPUT_PULLUP);
pinMode(PA7, OUTPUT);
}
void loop() {
//read the pushbutton value into a variable
int sensorVal = digitalRead(PA3);
//Contolling the LED from the pushbutton:
if (sensorVal == HIGH) {
digitalWrite(PA7, HIGH);
} else {
digitalWrite(PA7, LOW);
}
}