Standards

From Curuxa

Nomenclature

All Main Boards and Modules follow a common naming scheme based on short, easy to remember acronyms. You can see this scheme at the following places:

Data Connector

Data connectors are a standard configuration for intercommunicating Main Boards and Modules.

Simple data connectors are rows of three pins:

Pin number one, which is always the one closer to the microcontroller, is the data pin. All analog or digital information travels through this pin.
Pin number two, the one in the middle, is Vcc. It's the power line. It can be used for powering any module. The standard voltage is 5V, usually all Main Boards and Modules share the same power supply at this voltage and are all powered though this line.
Pin number three, the one further away from the microcontroller, is GND (power ground). It's the common voltage reference for all electronic circuits (Main Board and Modules) in your application.

Simple modules which only need one data pin would be connected to the Main Board using a three-pin female header.

Modules that require two data pins would be connected to the Main Board using a six-pin, double-row female header, or two data connectors.

Complex Modules that require more than two data pins would design their own connectors, and they may have different connectors for power and data pins.

Main Board showing data connectors

Data pins shown on a MBP14 layout (this Main Board accepts up to 12 data connectors)

Three-pin female header (schematic)

Standard data connector

Original data connector	Male side	Male side
Male side, plastic removed	Female side	Pinout

The female connector can be used to extend the length of another data connector, but it's usually removed when building a Module, because Modules only need the male side for being connected to a Main Board

You often will need to remove with a cutter the little extra plastic next to the pin #1, in order to be able to fit it in most Main Boards.

Homemade data connector

You can also build your own Data Connectors from scratch. You only need a 3-pin female header strip, some wire some heat-shrink tubing, and a few minutes.

Data connector from a simple module

Connecting Modules

One Module connected to an MBP40

MBP18 with some simple Modules connected to it

ICSP Connector

ICSP (In-Circuit Serial Programming) are the microcontroller programming pins. It is an interface and protocol developed by Microchip and used by all of their microcontrollers and DSP-controllers.

It consists of six digital input/output pins:

Vpp. Programming/reset pin. When the programmer (PICkit, ICD...) sets Vpp at around 12V, the microcontroller enters programming mode.
Vcc. Power pin. It's used when the programmer is powering up the entire circuit from the computer, so you don't need an external power supply.
GND. Ground.
Data. Programming data travels through this pin.
Clock. Programming clock for synchronizing the data being transferred.
NC. Not used for programming. Leave it disconnected.

The connector used by all Main Boards is the standard PICkit connector, so you can plug them easily. Other programmers, such as ICD2, ICD3, ICE... use other connector types, but they are all based on the same pins, so you can build adapters easily.

ICSP connector schematic

Main Board pinout

PICkit 2 pinout

MBP18 plugged to a PICkit 2

MBP40 plugged to a PICkit 2

MBP18 plugged to a PICkit 2

Power Connector

Two pins are used for connecting the power lines between Main Boards and Modules when a standard Data Connector is not used, and powering your circuits from external power supplies.

Pin 1 is always Vcc, the power line (usually a red wire). Pin 2 is ground (usually a black wire).

Most Main Boards don't have independent pins for Power Connectors. If you need to plug an external power supply to it, or power a Module using a Power Connector, you can use any empty Vcc-GND pair. Doing that would prevent you for plugging a Data Connector there, but that's usually not a problem because you will have empty connectors in most of your designs.