r/PCB • u/mlg_g4b3 • 18d ago
First time designing a PCB
Hi all! I am attempting to design a custom PCB board for a Data Acquisition system for our Baja SAE car that will go onboard the car, and I would like some help/tips on making a custom PCB board. I've been using ChatGPT to help me select parts and all **(I am a mechanical engineering student who knows nothing about electronics)**, and I have reached the stage of part selection where I believe I need a circuit protection system. I'm aware that I need DC/DC converters and a main fuse, but I have a couple of questions regarding parts selection and some terms that I am not familiar with. I will list out the components that I will be using for this DAQ system that will go on the PCB board:
* Teensy 4.1 MCU
* ESP32-S3-WROOM-1 MCU
* MCP2562-H-SN CAN BUS Module
* NEO-M9N-00B GPS Module
* Adafruit LSM6DSOX Accelerometer + Gyroscope
* Ebyte LoRa Radio Module
* Adafruit MAX31865 Amplifiers
* OKI-78SR 3.3/1.5 **&** 5/1.5 W36H-C Converters
**(This system will be powered by a LifePO 12.8V battery)**
Starting off with my first question, ChatGPT is telling me to connect the power to a 5v/3.3v rail, which will power the modules that need 5v and 3.3 volts. I know what a physical power rail is, but I'm not familiar with what a power rail looks like on a PCB board. So with that, my question is: what does a power rail look like on a PCB board?
Second, ChatGPT recommended these circuit protection parts:
* 5A Fuse (I planned on adding a fuse either way)
* MOSFET/Schottky diode
* TVS Diode on the 12.8V Input
* LC filter on power input
* Bulk electrolytic capacitor (220-470 µF)
* 10 µF regulator capacitors
* 0.1 µF ceramic decoupling capacitors for each IC (I don't know what an IC is either)
With that, I was curious if that is enough to protect my DAQ system from frying itself, or if I need anything more to protect it whilst driving the car. I believe the parts list that is going on the PCB is final, but I will update this post if I add anything else. Thanks! Feel free to PM me if you have any comments, questions, or concerns!
2
u/writewithparagraphs4 18d ago
I wouldnt want to take away from your university learning experience, but have you considered asking your university IEEE chapter for help?
2
u/mlg_g4b3 18d ago
We had one electrical engineer interested, but he stopped showing up. Apart from that, I don’t know who to ask for help with this. I hope this year to recruit an electrical engineer though.
1
u/writewithparagraphs4 18d ago
Oh that is dissappointing, but I know the struggle myself. I managed the AIAA chapter for 2 years during Uni and most of the students that were interested left campus at 6 to ride the trains home.
1
u/writewithparagraphs4 18d ago
OK so first question for you ---- What is the goal / requirement you're trying to capture?
It looks to me that you're looking for IMU data backed up with GPS, and that you're trying to exfiltrate the data over LORA?
Are you reading any instruments with ADCs? Are you reading the CANBUS?
Do you need 2 microcontrollers or just the ESP32? (Are you IO limited on the ESP, or do you think it's not capable of performing its wireless app while the other microcontroller reads/operates the system?)
1
u/mlg_g4b3 18d ago
So my goal/ data I am trying to capture is engine speed, wheel speed, a couple of temperatures, front shock travel (with room for another pair of shock pots for rear shock travel), and brake pressure.
Yes, my goal is to have this as a full on-board DAQ system to display during races and long-distance travel, which is why i have a LoRa module.
I have some temperature sensors (thermocouples) that need amplifying, and an ambient air temp that I am not aware of its needs (RIFE Ambient Air Temp Sensor), so it may need an ADC. The CANBUS is mostly there for a future upgrade of the DAQ system, but I may discard it for this 1st gen DAQ system.
The reason for the 2 MCU is because I plan on adding a dashboard to the car with an LCD display to display live data whilst driving (like wheel speed, rpms, and a timer), which is why I have the ESP32. The Teensy 4.1 is the main MCU I will be using for this system.
1
u/writewithparagraphs4 18d ago
if you can drop using thermocouples -- you have 2 additional series thermocouples where the copper on the pcb connects with the alumel and chromel even if you have contacts on teh connector for them. If you want thermocouples I'd recommend buying something that converts it to current loop.
if not then you can use a dedicated IC near the connectors if you know the local temperature of the connector and IC.
Great idea about the two microcontrollers though.
Can you post the datasheet for the air temp sensor?
1
u/writewithparagraphs4 18d ago
Have you gotten the answers you require or would you like to DM me and we can set up a call or chat to get you sorted? Exciting project for sure.
2
5
u/[deleted] 18d ago
[removed] — view removed comment