A Look at Dev Board Philosophy

TAP-28_mini

A huge variety of dev boards are available for PIC processors.  The choices can be bewildering.  This is a look at the types of boards available and for what situations a given board might be appropriate.  The few boards shown here are examples only and don't represent all of the available options.  The appearance of a particular board here should not be taken as a recommendation.

 

Be warned that some of my comments are biased and self-serving Embarassed

 

Full-Featured Development Boards

These boards have many peripherals on board and are a platform for experimenting and developing code techniques.  Features may include switches arranged in a keypad configuration, graphic and character LEDs, seven-segment readouts, LEDs, buzzers, various sensors and transducers and even more.

The EasyPIC 6 board from mikroElektronika is a prime example of this type of board.  A nice review of the EasyPIC 6 can be found here.  This board has no prototyping area, but all of the port pins are available for external connections via headers.

EasyPIC6-2

These boards can be quite expensive, costing $200 or more with all the accessories.

Pros:

  • Boards of this type are great for learning software and hardware, since so many peripherals are available just by setting switches.
  • External boards may be attached via jumpers to headers.

Cons:

  • It can be difficult to determine exactly what is connected to given port pins.
  • Prototyping with components not on the board requires jumpers to a proto board.
  • Connection to external devices may result in a rat's nest of jumpers.
  • Boards of this type are simply too expensive and large to be dedicated to a project.

 

Hybrid Development Boards

A step down from full development boards are hybrid boards.  They have some of the features of a development board, but not all the bells and whistles. 

The board from Sure Electronics that I reported on previously falls into this category.  It has a character LCD, a seven segment display, several push buttons and LEDs, a temperature sensor, buzzer and UART-USB converter. There's no prototyping area, but all of the port pins are available for external connections via headers.

This example board offers incredible value for the price.

Sure_PICDEM2PLUS_2

 

Pros:

  • Lower cost than full-featured development boards.
  • Good learning tool with a number of peripherals on-board.
  • Serial communications to PC via USB.
  • All port pins available via headers for external connections.
  • Reasonable cost, so this type of board could be dedicated to a project, particularly if a display is needed,

Cons:

  • Lack of flexibility in connection of on-board peripherals.
  • Prototyping with components not on the board requires jumpers to a proto board.
  • On the example board, micro is SMT, soldered in.  Using a different part is difficult.
  • Connection to external devices may result in a rat's nest of jumpers.

 

Development Boards With Prototyping Space

PIC applications frequently require components in addition to the  micro controller.  Development boards are available with few features but have an area to add what you need.  The PIC-Ready from microElectronika has the bare bones parts to make a PIC operate and a prototyping area.  Unlike many of the bare-bones boards, the port pins are brought out to headers so that other needed boards may be attached.  Notice the lack of even a single LED or switch prevent even basic testing without adding components.

PICREADY-1

Similar boards from Olimex have a large prototyping area, a jumper selectable LED and push button switch and either a MAX232 UART-RS-232 chip or a UART-USB adapter chip.  Unlike the PIC-Ready board, there are no headers for connecting external boards.  Any connections to the PIC must be made by soldering connections to the board.

olimex-serialolimex-usb

 

Pros:

  • Prototype area allows adding circuit in a more durable way than using a proto board and jumpers.
  • Boards may have often-needed peripherals on the board (i.e., voltage regulator, serial interface, port-interfaced LED and switch).
  • Boards are lower cost.
  • A good choice for dedicated applications.

Cons:

  • Adding components and testing different applications may requiring soldering parts.
  • External connections may require solder connections.
  • Not too useful as a learning tool to try different hardware and software features.

 

Boards Using Daughter Boards (aka Shields)

The newly introduced Amicus board follows the path of the popular Auduino, except uses a PIC 28-pin processor (the 18F25k20 only is supported by the Amicus compiler).  By itself, the Amicus falls into the bare bones dev board area.  There's enough hardware to interface to the PIC and make it run, but it lacks even an LED or switch to allow basic testing. 

Amicus

The power and flexibility of the Amicus board comes through the addition of daughter boards or shields in the Auduino parlance.  Prototyping boards, GPS receivers, Ethernet adapters, motor controllers and many other functions are available in the form of a shield.  The Amicus is even compatible with many Arduino shields.

The picture below shows Graham's project of interfacing a Sure DS18B20 temperature probe to the Amicus using a proto-board shield.

amicus_in_use

 

Pros:

  • Offers tremendous flexibility through the use of accessory shields;
  • Offers a powerful programming language at no charge when used with the Amicus compiler.  A boot loader simplifies loading program code (although boot loaders may be used with almost any board that has an RS-232 or USB interface).  Note that the Amicus compiler may be used with any board that supports an 18F25K20.
  • A large number of Arduino shields may work with this platform (but code will have to be written).
  • Can be easily customized through the use of shields to a particular application.  It may be possible to use several shields simultaneously.

Cons:

  • The cost of an Amicus board + appropriate shield may be more expensive than other alternatives.
  • The Amicus board itself lacks even basic development aids such as LEDs and switches.
  • Connections to external components requires either an appropriate shield or jumpers from the header connectors.

Demonstration Boards

This type of board is available to show off the features of certain parts.  They are usually fully programmable but usually don't offer any prototype area or port connections off the board.  If you plan to use a demonstration board to run your own code, make sure there is a ICSP connector or other means to program the PIC.

There are literally thousands of demonstration boards offered by manufacturers.  Some include a micro controller, others may be for power supplies, sensors or other peripherals.  The two shown here are boards I have.

Microchip MCP9800 Temperature Sensor board: Using an 18F2550, this board features a MCP9800 temperature sensor (naturally) and a seven-segment readout and the all-important  mounting pads for a standard ICSP connector.  Conveniently, this board also features solder pads for I2C SDA and SCL lines which can be re-purposed for your application. (Be advised that the seven segment display is connected to pins from several ports, making its control a bit of a pain.)  This is a nice board for developing USB applications on the 18F2550.

MCP9800

 

The Microchip MPLAB Starter Kit for PIC18F MCU (Part Number: DM180021)  features a graphic LCD, a touch-sense pads, accelerometer, SD card slot and other features and uses a PIC18F46J50 (which unfortunately is not supported by Swordfish).  No external connections other than a provision for an ICSP connector are available (actually, the full D port, power, ground and 8 other signals are available under the sticker on the right).. 

18F_Starter_Kit2

Pros:

  • Good learning tool for particular hardware.
  • May be re-purposeable for other applications.
  • Usually inexpensive.

Cons:

  • Usually do not include prototyping area or off-board connections.
  • Usually not designed to be a general-purpose dev board.

 

Application Boards

The TAP-28 board could fit into several of the above categories, but it really shines when it comes to real-world applications.  While all the port pins are available via headers, and several switches and LEDs are on the board, the TAP-28 is designed to be an applications platform dedicated to a project by being very low cost and having dedicated connectors for connecting real-world devices.

TAP-28_copy_copy

 

Consider some typical applications:

Servo Clock

The TAP-28 board has four 3-pin headers in the standard servo arrangement.  For the servo clock, the servo was plugged into the board directly.  In the picture below, the servo cable is on the right side, going up and disappearing behind the front of the clock to the servo.  The red, blue and black jumpers are connections to a pot, used for calibration only.

servo_clock_2_-_tap-28-sm

 

TTL Serial Connections

In some real-world applications, it's necessary to communicate and control another board via a seral connection.  The TAP-28 board has a dedicated 6 pin UART connector with connections to power, ground, Tx, Rx and two additional port pins for handshaking or other use.  It's a direction connection to use the PICkit 2 UART tool as shown in the above picture.  To test the Sure RF UART modules, jumpers were used as shown in the picture below, but in a real-world application, a jumper cable would be built.

TAP-28__RF_Mod

 

Sensors and Transducers

Real-world applications often use some type of analog sensor, which usually requires connection to power, ground and analog input.  Two 3-pin headers on the TAP-28 support analog sensors.  Other sensors, such as the xxxx light meter chips, have a digital output where the frequency is proportional to analog level.  Four 3-pin headers can handle sensors of this type.

The Dallas 18B20 temperature sensor uses the proprietary One-wire protocol.  One-wire sensors need power (sometimes), ground and a digital I/O line.  The 3-pin connectors seem ideal for this except that the sensors require a pull-up resistor on a data line.  The TAP-28 board has a 6 pin connector for I2C/SPI, which has jumper-selectable 4.7k pull-up resistors on the board (note - in my article on using the 18B20, I inadvertently indicated a 10k pull-up was used)).  The photo below shows the connections used for testing - 3 simple jumpers.  In a real-world application, the temperature sensor connector could be re-arranged to support direct connection to the TAP-28.

DS18B20_test_setup

 

A Remote Control Panel

Embedded projects may need some kind of user interface beyond the switches and LEDs on the TAP-28.  With 4 port pins, power and ground available, the I2C/SPI connector is a great way to accomplish this.  Since 3 of the port pins have pullup resistors on the board, connecting up to 3 push-button switches is simple - just connect each switch between a port pin and ground.  LEDs are slightly more difficult - a series resistor must be added for each LED.  The world sees a pretty interface panel and the "brains" hides out behind the panel.

Pros:

  • Ideal board for dedicated applications.
  • Connections to many external devices are simple and reliable with dedicated connectors.
  • Low cost platform for dedicated applications.
  • Includes basic necessities for program development.

Cons:

  • Prototyping requires the use of a proto board and jumpers.
  • To keep costs low, a regulated power supply must be used.

 

Summary

Development boards are available with a wide range of features and at a wide range of prices.  The intended use of a board would influence the purchase.  The boards shown here are just a few representative samples of what's available.

 


Posted: 3 years 11 months ago by Anonymous #5510
Anonymous's Avatar
You're right about the TAP-28 fitting into a few of the different types of dev boards - it's quite the all-rounder!

What appeals to me is how the TAP-28 balances the rift between prototyping and production. An end user can have a fully populated TAP-28 which they can prototype with, and can use the very same development board (populated with only the components required) when it comes time to firm things up. Better yet, the price makes the whole ordeal worth-while compared to custom PCB design.
Posted: 3 years 11 months ago by Anonymous #5511
Anonymous's Avatar
Hi Guys,
I have the Sure electronics board and cant get the LCD to initialise in Proton.
I've used the code on here for Swordfish and it works perfectly...
Anyone use Proton that can help me please


Edit: This comment has been answered on the forum - viewtopic.php?f=13&t=779

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