Ham Radio: Workbench 15 – Micro Controllers in the Real World

In this episode, George and Jeremy explore how to connect micro controllers and single board computers to circuits and sensors to interface with the real world.  They discuss both analog and digital inputs and outputs as well as the most common ways of interfacing with components such as sensors.

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Show Content

Micro Controller Input/Output Pins
Analog vs Digital
Logic Levels Overview
TTL 5V Logic Levels
CMOS 3.3V Logic Levels
Pull Up Resistors for Digital Inputs
Analog to Digital Converters
Voltage Dividers
Pulse Width Modulation Output

Serial communications
Overview
I2C
SPI
UART

Sensors
https://www.sparkfun.com/categories/23
https://www.adafruit.com/category/35

4 comments

  1. Hi Guys,

    Listening to the podcast you were talking about some copper on the PCB becoming a fuse. I have some experience with this and some info that can help. Assuming you are working in inches the formula for figuring out the resistance of a copper trace is R=L*(6.5866E-7)/WT. L=Length, W=Width, and T= Thickness.
    1 ounce copper thickness is 0.00135 usually called 1.3 mils thick.

    Example:
    If your trace is 0.1 inches wide and 1 inch long the resistance will be
    R=1*(6.5866E-7)/(0.1*0.00135)= about 5 milliohms.
    You mentioned putting 40 amps through it so the power dissipation would be 40*40*.005 or about 8W.
    That’s quite a lot.

    If you go to 2 ounce copper and two sided PCBs to parallel traces power will drop to 2W with double the surface are to dissipate the heat.

    Good luck!
    Mike

  2. Guys, I was just listening to your podcast on micro-controllers, in particular serial communications. I frequently use RS-485 as it is pretty much impervious to noise. It can run as fast as 38400 baud overr 4 wires. The devices can have any address between 0 to 255. Another serial interface with device addressing is Modbus.
    Thanks for a really informative and interesting podcast. Good work.

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