This document describes connector system used in BigClown and the signals available on the connectors.

The BigClown IoT Kit emphasizes hardware modularity and reusability. In order to achieve such goal, the proper interconnection system has to be used. BigClown sticks to a well-known and widely accepted standard - the so-called headers with a 2.54 mm (0.1 inch) pitch.

The BigClown header system consists of two types of components - pins and sockets.


TODO Photo of a module with legend to pins and sockets.


To keep compatibility between various hardware components, the two BigClown electro-mechanical formats have been defined - module and tag.

Module Format

Format Module defines:

  • Spacing and signals between two rows of 14-pin headers (see table below)

  • Four mounting hole positions and their diameter

  • Position of mechanical key (filled hole in header) preventing reverse insertion

  • Position of sockets from top view

  • Position of pins from the bottom view

  • Recommended PCB height 55 mm

  • Recommended PCB thickness 1.5 mm

  • Radius of rounded corners 3.8 mm

Module Drawing

Module drawing

Module Signals

This is a summary of basic peripherals available on the module header:

  • 18x GPIO channels (General Purpose Input/Output)

  • 6x ADC channels (Analog-to-Digital Converter)

  • 2x DAC channels (Digital-to-Analog Converter)

  • 3x UART channels (Universal Asynchronous Receiver Transmitter)

  • 2x I²C bus (Inter-Integrated Circuit)

  • 1x SPI bus (Serial Peripheral Interface)

The following table defines signal assignment on module header:

Pin Signal Description
1 P0 GPIO channel 0
A0 ADC channel 0
TXD0 UART channel 0 - TXD signal
2 P1 GPIO channel 1
A1 ADC channel 1
RXD0 UART channel 0 - RXD signal
3 P2 GPIO channel 2
A2 ADC channel 2
TXD1 UART channel 1 - TXD signal
4 P3 GPIO channel 3
A3 ADC channel 3
RXD1 UART channel 1 - RXD signal
5 P4 GPIO channel 4
A4 ADC channel 4
DAC0 DAC channel 0
6 P5 GPIO channel 5
A5 ADC channel 5
DAC1 DAC channel 1
7 P6 GPIO channel 6
RTS1 UART channel 1 - RTS signal
8 P7 GPIO channel 7
CTS1 UART channel 1 - CTS signal
9 P8 GPIO channel 8
10 P9 GPIO channel 9
11 RESET System reset
Also button "R" on Core Module
12 BOOT Boot mode
Also button "B" on Core Module
13 VDD_OFF From top side: VDD_OFF_OUT
From bottom side: VDD_OFF_IN
14 BAT_OFF Battery disconnect signal
15 GND System GND (ground)
16 VDD System VDD (positive rail)
17 SCL0 I²C bus 0 - SCL signal
18 SDA0 I²C bus 0 - SDA signal
19 INT System interrupt signal
20 System interrupt signal
21 P10/RXD2 UART channel 2 - RXD signal
22 P11/TXD2 UART channel 2 - TXD signal
23 P12/MISO SPI bus - MISO signal
24 P13/MOSI SPI bus - MOSI signal
25 P14/SCLK SPI bus - SCLK signal
26 P15/CS SPI bus - CS signal
27 P16/SCL1 I²C bus 1 - SCL signal
28 P17/SDA1 I²C bus 1 - SDA signal

Tag Format

The primary purpose of tag format is to provide signal break-out for I²C peripheral in a compact form-factor. It can be anything I²C-related - e.g. sensors, memories, RTCs, etc.

Format tag defines:

  • Signals on a 5-pin header (see table below)

  • Letter "D"-shaped PCB outline

  • Mechanical dimensions 16 x 16 mm

  • Recommended PCB thickness 1.5 mm

  • Radius of rounded corners 3.8 mm

Tag Drawing

Tag drawing

Tag Signals

The following table defines signal assignment on tag header:

Signal Description
1 GND System GND (ground)
2 VDD System VDD (positive rail)
3 SCL I²C bus - SCL signal
4 SDA I²C bus - SDA signal
5 INT System interrupt signal