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. Usually all microcontrollers, integrated circuits and Modules work at the same voltage (2.5-5V), and they are all powered though this line.
Pin number three, the one further away from the microcontroller, is GND or 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.

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

Main Board with some simple Modules connected to it

Data connector from a simple module

Data pins shown in a Main Board layout

Three-pin female header (schematic)

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.