Technology Alternatives - Summary, Conclusion, Recommendation

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

Summary, Conclusion, Recommendation

The following two charts provide a summary of my conclusions after an initial period of "hands-on" evaluation.

 

My conclusions, in narrative form, were summed up as follows:

• Cost does not seem to be a huge issue given that all of the solutions are close in terms of required investment.
• Customer requirements that demand a high degree of computation for analysis could make the single-board computer alternatives attractive given the limited memory available on the Arduino boards.
• The Arduino Mega would be the recommended choice if an Arduino were to be used given it has much more memory than the Uno. 
• The Arduino provides the most simple hardware solution though it’s reliance on “C” as a development language, and without an IDE as good as the BeagleBone Black, adds complexity on the software side.
• The Raspberry Pi, with an Arduino, provides a very flexible solution but at the cost of complexity with two hardware environments and two languages.
• The Raspberry Pi, with an ADC, was a bit more challenging to integrate than was expected though in most other respects it has been easy to work with to date..
• The BeagleBone Black could provide the best overall solution from a hardware and software complexity perspective though it’s user community does not seem as strong as that of the Raspberry Pi.
• At this point in the investigation I would recommend the Arduino Mega with an external ADC or the BeagleBone Black.   
• While the BeagleBone Black merits further investigation, particularly around the user interface, it has been very impressive to date:
• Combines features of Raspberry Pi and Arduino in one package,
• Includes 12bit resolution on board with a high sample rate,
• Looks and feels more “industrial strength” than the Raspberry Pi (and is faster),
• Provides a very user friendly development environment with some characteristics similar to Visual Basic,
• Allows for easy porting of code from Arduino given language similarities.

 Final decision was to pursue a BeagleBone Black solution.

Technology Alternative - BeagleBone Black

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

BeagleBone Black

• BeagleBone Black Hardware (50):
• 1ghz ARM CPU
• 512mb of Memory
• Storage on Flash Card or USB
• Graphics Accelerator and Floating Point Processor
• Initially developed by Texas Instruments in 2008.  Current device seems to have been released at an RPi competitive price point.
• RPi Software:
• Fully functional Linux implementation with Javascript as primary programming language (though Python is also supported).
• Javascript IDE supports interactive debugging and as such has some similarity to Visual Basic.
• Vast selection of software available to meet development requirements.
• Initial impression is that user community is not as strong as that of the RPi.
• Provides 12bit resolution for Analog to Digital conversion via onboard hardware.  Inputs must be below 1.8v.
• Supports several LCD displays as add-ons, called “capes”.

Notes:
(1) The breadboard provides a voltage divider that uses a variable resistor to deliver a variable voltage for simulating a test measurement.  It is also supporting a tri-colour LED as a status monitor while a test is running.
(2) LCD ‘cape’ shown is one of several options for a User Interface.

Technology Alternative - Raspberry Pi with External ADC

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

Raspberry Pi with External ADC

• Raspberry Pi (Rpi) Hardware (50):
• 700mhz ARM CPU
• 512mb of Memory
• Storage on Flash Card or USB
• RPi Software:
• Fully functional Linux implementation with Python as primary programming language.
• Vast selection of software available to meet development requirements.
• Extremely strong user community for support
• External ADC chip integrated with the Raspberry Pi via I2C (a serial communications protocol)
• Provides up to 18bit resolution for Analog to Digital Conversion 
• Could provide user interface through one of several available LCD displays

The breadboard provides a voltage divider that uses a variable resistor to deliver a variable voltage for simulating a test measurement.  It is also supporting a tri-colour LED as a status monitor while a test is running. 

Technology Alternative - Hybrid = Arduino + Raspberry Pi

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

Hybrid = Arduino + Raspberry Pi

• Raspberry Pi (Rpi) Hardware (50):
• 700mhz ARM CPU
• 512mb of Memory
• Storage on Flash Card or USB
• RPi Software:
• Fully functional Linux implementation with Python as primary programming language (though certainly not the only language supported).
• Vast selection of software available to meet development requirements.
• Extremely strong user community for support
• Does not have onboard Analog to Digital conversion and so needs another device for integration with physical devices.
• Arduino hardware would be per previous example (65)
• Very high sample rates (+/- 600/sec) possible with logging by Arduino to SD Card and then upload to Raspberry Pi.
• Could provide user interface through LCD integrated with the Arduino or by integrating an LCD with the RPi (the former being what is shown as I do not have an LCD on my RPi.

Notes:
(1) The breadboard provides a voltage divider that uses a variable resistor to deliver a variable voltage for simulating a test measurement.  It is also supporting a tri-colour LED as a status monitor while a test is running.
(2) LCD display has not been integrated with the Raspberry Pi as of this picture but is shown for illustrative purposes

Technology Alternative - Arduino Mega with LCD Touchscreen

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

Arduino Mega with LCD Touchscreen

• Hardware:
• Arduino Mega 2560 (40),
• TFT LCD Shield (10),
• TFT LCD/Touchscreen Shield (15)
• Microprocessor:
• Flash Memory - 256KB of which 8 KB used by bootloader
• SRAM - 8 KB
• EEPROM - 4 KB
• Software:  Arduino sketches written in C++ and downloaded to the microprocessor from a workstation.
• Supports 10bit resolution for Analog to Digital Conversion (external adapter can be added for higher resolution).
• Capable of taking 250 fixed time slice samples per second (assuming no updates of the LCD during sampling).
• LEDs could be used for indicating status during a capture (blink each second).  Shown upper left in picture to the right.

The breadboard provides a voltage divider that uses a variable resistor to deliver a variable voltage for simulating a test measurement.  It is also supporting a tri-colour LED as a status monitor while a test is running.

Technology Alternative - Arduino Uno with Simple LCD Display

This post is part of a thread titled "What Technology to Choose for a Physical Interface Project"

Arduino Uno with Simple LCD Display

• Hardware:
• Arduino Uno (15),
• SD Card Shield (15),
• Screwpoint Adapters (10),
• LCD with Keypad Shield (10)
• Microprocessor:
• Flash Memory - 32 KB (ATmega328) of which 0.5 KB used by bootloader
• SRAM - 2 KB (ATmega328)
• EEPROM - 1 KB (ATmega328)
• Clock Speed - 16 MHz
• Software:  Arduino sketches written in C++ and downloaded to the microprocessor from a workstation.
• Supports 10bit resolution for Analog to Digital Conversion (external adapter can be added for higher resolution).
• SRAM limits board to taking 125 fixed time slice samples per second (assuming no updates of the LCD during sampling).
• LEDs could be used for indicating status during a capture (blink each second).

 

The breadboard provides a voltage divider that uses a variable resistor to deliver a variable voltage for simulating a test measurement.

What Technology to Choose for a Physical Interface Project?

High Level Project Requirement

Goal of the project will be to integrate a piece of test equipment with a user friendly and computationally capable front-end that can operate without being attached to a dedicated computer.   The host needs to capture observations from a single analog source (at a rate of between 100 and 200 obs/sec), provide real-time feedback, and save the captured data to be presented with some other analysis tools.

Obviously I had a fair amount of experience with the Arduino and with the Raspberry Pi but I also wanted to look at another single board computer.   A survey of the market led me to the BeagleBone Black.   Given this, the alternatives that were investigated on a hands-on basis were:

• Arduino - a single-board microcontroller designed to make the process of using electronics in multidisciplinary projects more accessible.
• Raspberry Pi - a credit-card-sized single-board computer developed in the UK by the Raspberry Pi Foundation
• Beaglebone Black - a low-power open-source hardware single-board computer produced by Texas Instruments in association with Digi-Key.

There are a variety of other technologies but these three represent what I feel to be the best of those other alternatives.