Raspberry Pi

What should be the next step for the club with respect to promoting the Raspberry Pi?

I am thinking about:

  1. an install fest where everyone installs the software on a SD card, boots it up and leaves with a working copy of WSPR.  See http://wsprnet.org/drupal/wsprnet/map, http://physics.princeton.edu/pulsar/K1JT/wspr.html, http://hackaday.com/2013/03/21/wspr-transmitter-shows-true-value-of-raspberry-pi-for-hacking, and https://github.com/threeme3/WsprryPi
     
  2. a basic hardware interfacing session - blink LED's, read switches, activate relays, spin DC brushed motors, read encoders, pulse width modulate a LED
  3. stepper motor interfacing
    - dumb H-bridges: L293D (two direction and step pulse pin)
    - smarter step controllers such as Allegro A4988 (direction and step pulse pins)
    http://www.pololu.com/catalog/product/1182
  4. RS232C communication interface to other microprocessors via Firmata serial protocol
    - $30 Arduino's
    - $13 ARM Cortex M[0-4]'s
    http://firmata.org/wiki/Main_Page
  5. high speed SPI and I2C interfacing
    - intelligent stepper controllers that execute a motion profile with target speeds, distances and accelerations, analog to digital converters
    https://www.tindie.com/products/ElectricLaboratory/chainable-intelligent-stepper-driver-l6470/

That sounds pretty sweet to me, Greg.  I'd be in for some tinkering.  I've already got an arduino kit, but I'd be excited to learn about this other stuff as well!

Perfect!

The RPi GPIO pins are 3.3 Volt.  Some Arduinos are 3.3V parts and can wired directly to a RPi.  Most Arduinos are 5.0 V parts and need a level shifter to convert the 5.0 volt levels to the 3.3 volt levels on the RPi. 

A 5 volt to 3.3 volt per-pin level shifter can be built with some pull up resistors and a diode.

With the 3.3 volt levels sorted out, a RPi can be used to set and read Arduino pins via the Firmata protocol with the UART serial ports wired together.

Easy to do!


Only just found out that this site had a forum…

I've done quite a bit with Firmata from Raspberry Pi, but only through USB. pyfirmata works quite well. I should really go back and retry Processing, which was deadly slow last year, but is what most people use to talk through Firmata to something else.

I've added an RTC (an “expensive” TCXO controlled DS3231, for $7) to the Raspberry Pi that runs my lights through X10.

The cheap Nokia 5110 screens are easy to support on the Raspberry Pi. For some reason, I made this: the Quite Rubbish clock.


Central Toronto Amateur Radio Club

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