recommended hardware

[KRD]

Hi,

I made some small projects with the cool stuff you are selling and now its time for a new project. I want to build a sequential shiftlight for my car. Because of the fact the product range is so big I thought I would ask you which hardware would suit best for my project.


- I would like to measure a frequency from 0 to 500Hz.
- I need 13 digital inputs for presetting the rpm range etc. with dipswitches
- I would like to use 8 LEDs with the ability of dimming
- I need 2 analoge inputs to set the brightness of the LEDs

My experience is limited to working with Arduino so I thought of using an Arduino Nano with your Adafruit AW9523 GPIO Expander and LED Driver Breakout - STEMMA QT / Qwiic Product ID: 4886
But I would be open for new things.

Another thing that would be interesting for me is the power supply. I used 7805 in my earlier projects but I was wondering if there is a finished product available that makes the voltage of the car to 5V and filters the interferences from the alternator?

The goal is to build this small in size. Hopefully you can give me advice which hardware would be the best for me to buy.


Regards

[adafruit_support_mike]

I would like to measure a frequency from 0 to 500Hz.

Pretty much any microcontroller can do that. The basic idea is to count the pulses for some known amount of time.

the limit of resolution is half the lenght of the counting interval. If you want to know the frequency in 1Hz increments, you need to count pulses for at least 2 seconds. If you can live with steps of 10Hz you only need to count for 200ms, and so on. You need at least two pulses of the slowest frequency.

I need 13 digital inputs for presetting the rpm range etc. with dipswitches

To get that many GPIO pins on a dev board, you’d need to use something the Grand Central:

https://www.adafruit.com/product/4064

You can also hand the job off to a GPIO expander like the AW9523:

https://www.adafruit.com/product/4886

which has 16 IO pins and communicates with a microcontroller via I2C.

I would like to use 8 LEDs with the ability of dimming

You have a range of options there.. you could use regular LEDs and control them with PWM from a microcontroller’s GPIO pins, you could use an LED driver like the TLC59711:

https://www.adafruit.com/product/1455

or you could use NeoPixels, which only need one data line for the whole strip:

https://www.adafruit.com/category/168

- I need 2 analoge inputs to set the brightness of the LEDs

Another thing that would be interesting for me is the power supply. I used 7805 in my earlier projects but I was wondering if there is a finished product available that makes the voltage of the car to 5V and filters the interferences from the alternator?

Use an automotive USB adapter.

Dealing with a car’s electrical system is a specialty field, and the adapters already have all the features needed for the job. They’re also cheap and easy to find, so choosing not to use one would mostly be a decision to dive into that field of design.. and then the first thing you’d want to do is buy half a dozen existing adapters to crack open and study.

The ‘7805 is a well-respected regulator with a long engineering history, but its efficency gets pretty bad when the input voltage gets higher than about 7V. The circuit is basically a smart resistor that adjusts its own resistance to keep the output voltage at 5V for whatever current load is present, so the energy from any excess voltage gets burned off as heat in the ‘7805. For a 12V to 14V automotive system, the extra 7V to 9V would be wasted energy.

These days we use swithing regulators for that kind of job. They can store energy in a magnetic field and change voltages more efficiently. The excess energy that would be burned off in a ‘7805 gets converted to energy pushing more current at 5V.