Thursday, May 03, 2018

A DIY Ecosystem for Learning Microcontrollers and Physical Computing

Microcontrollers are central elements in modern electronics as embedded computers. Most vendors offer many inexpensive evaluation platforms to showcase their microcontroller products. Typically such platforms (Arduino, MSP430 LaunchPad etc) fall short on the aspect of sensors and other digital I/O peripherals.

We set out to design a DIY-able sensors and peripherals board that anyone with access to simple PCB fabrication facilities, can recreate and further the task of learning about microcontroller programming and physical computing.

While Arduino remains a popular microcontroller learning platform, MSP430 which is a popular, capable and formidable microcontroller from Texas Instruments lacks an inexpensive learning platform. TI's MSP430 Launchpad  sells for about Rs. 1200 in India and can be prohibitive for some.

MSP430 LunchBox

To address the cost issue with an introductory MSP430 learning platform, we created the MSP430 LunchBox.  

MSP430 LunchBox is an inexpensive MSP430 learning platform that can be fabricated for personal use for under Rs. 100. The LunchBox board supports any 14-pin or 20-pin DIP package MSP430 G series microcontroller, which a hobbyist can obtain for free through the TexasInstruments’ free samples programme. The entire bill of material for the board, excluding the microcontroller, is under Rs. 100. The PCB has been designed in a single sided, toner transfer friendly format, allowing enthusiasts to fabricate one, at little or no cost. The photograph below shows the early lab prototype of the LunchBox.

The PCB board files used to fabricate the lab version of the PCB as seen above can also be mass manufactured for a more professional experience. The photograph below shows such a professionally manufactured board.





The table below lists the salient features of the LunchBox.

Feature
MSP430 LunchBox
Microcontroller
MSP430G2553 & others
CPU Architecture
16-bit
Operating Voltage
3.3V
Operating Clock
10 kHz to 16 MHz
Operating Current
4.5 mA @ 16 MHz
Programming
Factory UART BSL
Debugging
Not supported
Supported IDEs
CCS, Energia
Available I/Os
14
Analog Inputs
8
PWM Outputs
6
Peripherals
1 LED, 1 Switch, UART
Cost
Rs. 100/-


Sensors and Peripherals Board

Like the Arduino or the MSP430 Launchpad, the LunchBox too is devoid of any serious sensors or user peripherals. So,  to enrich the learning experience, we  developed two simple and inexpensive I/O expansion boards, the Mini-Voyager-1 and Mini-Voyager-2. As with the LunchBox, the Mini-Voyagers are also a single sided PCBs that can be fabricated at home or lab. The following tables list the salient features of both the Mini-Voyagers.

Feature
Mini-Voyager-1
LEDs
A single RGB LED
LED Display
4-digit Seven Segment Display
Temperature
Thermistor
Light
LDR
User Input
5-switch Navigation Switch

Capacitive Touch Input
Analog
Potentiometer
Pulse Wave
IC 7555 based adjustable astable multivibrator

Feature
Mini-Voyager-2
Display
16x2 LCD with Backlight Control switch
Switch
Single Pushbutton
Keypad
4x4 Keypad
Time
PCF8563 RTC with I2C and with Battery backup
Serial Bus
Shift Register with SPI Bus

RTC with I2C Interface
Sound
Buzzer

The photograph below shows both the Mini-Voyagers in the company of the MSP430 LunchBox.

Using LunchBox with Mini-Voyagers


To use the LunchBox together with Mini-Voyager-1 and/or Mini-Voyager-2 is as easy as 1-2-3.
1.     Write code in IDE.
2.     Connect the required peripherals from MV-1 or MV-2 to the LunchBox pins using male header pins provided on the board. 

3.     Connect the supply voltage of either 3.3 V or 5 V using male header pins provided on the LunchBox (other microcontroller platforms that work at 3.3V such as MSP430, MSP432, TIVA ARM as well as the BeagleBoneBlack can be used as easily. Microcontrollers that work at 5V can also be used with Mini-Voyagers.).
4.     Power the LunchBox using a USB mini cable.
5.     Upload the code. 
CODE CONNECT UPLOAD!

The photograph below shows LunchBox and Mini-Voyager-1 in action. More than 50 experiments and small projects can be performed using this ecosystem.


During a recent event, we had 10s of students solder, test and use the LunchBoxes and Mini-Voyager-1!

The LunchBox and the Mini-Voyager platforms have been developed at CEDT and TI-CEPD at NSIT. For more details, contact info@cepd.in


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