Building a Compact Avionics Telemetry System: A Step-by-Step Guide
The following post (including sub title above) was made with a single GPT4 prompt, as follows:
Prompt:
I want you to act as an Embedded systems engineer with editing experience. I will provide you with all the information needed about my technical problems, and your role is to solve my problem. You should use your knowledge of computer science, embedded systems infrastructure, and hardware design to solve my problem.
I am going to give you a list of requirements and using the requirements ask you to complete a number of tasks using the requirements. Write your answer as a blog post, while still completing each task. Do not reveal that you are following a set of tasks:
Task1 : Re-write the requirements as an engineer (group the requirements by into relevant catagories).
Task2 : Create a BOM that includes the name, manufacturer, part number, power requirement, communication method (if any), quantity, and cost. Use the components you would select if you needed to purchase and build the PCA.
Task3 : Describe the design of the circuit.
The following list are the requirements for the design:
-modern, small, fast, and easy to use microcontroller or FPGA
-gyroscope
-GPS module
-pressure sensor with read rate greater than 5000 samples/s
-1 mini-usb serial port for programming
-1 rs-232 serial port
-terminal block for battery input
-charge an 18650 battery
-dc jack for charging input
-fits inside a 38mm circle
-low power consumption
-reverse voltage protection
-all real components from DigiKey or LCSC
-inexpensive components
Further clarification: this PCA will be used as part of an avionics telemetry system.Welcome to this comprehensive journey where we will walk through the process of building a compact avionics telemetry system. Based on the requirement set we’ve been given, our aim is to create an efficient, cost-effective, and compact system that fits within a 38mm circle. Let’s start with grouping the requirements.
Reinterpreted Requirements
Core System:
- A modern, fast, small, and user-friendly microcontroller or FPGA.
Sensors:
- A gyroscope.
- A GPS module.
- A pressure sensor with a read rate greater than 5000 samples per second.
Communication:
- A mini-USB serial port for programming.
- An RS-232 serial port.
Power Management:
- A terminal block for battery input.
- A system to charge an 18650 battery.
- A DC jack for charging input.
- Low power consumption.
Safety Features:
- Reverse voltage protection.
Miscellaneous:
- All real components must be sourced from DigiKey or LCSC.
- Components should be cost-effective.
With our requirements laid out, let’s move on to creating our Bill of Materials (BOM).
Bill of Materials (BOM)
Given the requirements, here are the components that we would need for this build:
| Component | Manufacturer | PN | Voltage Req | Communication Type | Quantity | Approx. cost |
| Microcontroller | Microchip | ATmega328P | 1.8 – 5.5 V | SPI, I2C, UART | 1 | $3 |
| Gyroscope | Bosch | BMI160 | 1.8 – 3.6 V | SPI, I2C | 1 | $4 |
| GPS Module | u-blox | NEO-6M | 3.0 – 5.5 V | UART | 1 | $12 |
| Pressure Sensor | Honeywell | HSCDANN001PGSA5 | 3.0 – 5.0 V | SPI | 1 | $10 |
| USB-to-Serial Converter | FTDI | FT232RL | 3.3 – 5.5 V | USB, UART | 1 | $4 |
| RS-232 Driver | Maxim | MAX232 | 4.5 – 5.5 V | UART | 1 | $1 |
| Battery Terminal Block | Phoenix | MSTB 2,5/2-ST-5,08 | N/A | N/A | 1 | $1 |
| Battery Charger | TI | BQ24074 | 4.35 – 6.2 V | N/A | 1 | $2 |
| DC Jack | CUI | PJ-202AH | N/A | N/A | 1 | $1 |
| Reverse Protection IC | Vishay | VBUS05B1-DD1-G-08 | 5.0 V | N/A | 1 | $1 |
| 18650 Battery | Panasonic | NCR18650B | 3.7 V | N/A | 1 | $6 |
Note: All prices are approximated and may vary slightly.
Circuit Design
At the heart of our design is the ATmega328P microcontroller, chosen for its power efficiency, versatility, and cost-effectiveness. The microcontroller communicates with the BMI160 gyroscope, NEO-6M GPS module, and the HSCDANN001PGSA5 pressure sensor via I2C/SPI and UART interfaces. This facilitates real-time data acquisition from all sensors.
A mini-USB serial port, created using the FT232RL USB-to-Serial converter, is utilized for programming the microcontroller. This also provides a serial communication link over USB. An RS-232 serial port is also incorporated into the design using the MAX232 driver, enabling an additional, robust communication channel.
Power management is handled by the BQ24074 charger IC, connected to the terminal block for battery input, as well as the DC jack for charging input. It efficiently charges our selected 18650 battery while providing power to the rest of the circuit. A low dropout (LDO) regulator can be included to ensure a stable supply voltage for the entire system.
Safety is crucial, so a VBUS05B1-DD1-G-08 IC from Vishay provides reverse voltage protection. This safeguards the microcontroller and the other sensitive components from any accidental reverse polarity on the power inputs.
This system, with careful placement and routing, can fit within the required 38mm circular footprint. However, achieving this compact size could be challenging and may require a multilayer PCB design approach.
As part of the Avionics telemetry system, this PCA can collect crucial flight data in real-time with high reliability. While compact and inexpensive, this system doesn’t compromise on performance and robustness. Happy building!
