qbcan compact

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This document is the qbcan compact user manual. It describes the qbcan compact CanSat kit and the software setup. It provides a step-by-step guide to help the user go through the development process, from the opening of the qbcan kit to transmitting data from one qbcan to another.

The qbcan kit has been developed by Open Cosmos. Open Cosmos is a start-up willing to use nano-satellites to provide simple and affordable access to space to organisations ranging from SMEs and research institutions to space agencies in developing countries.

Open Cosmos is based in London with an international mindset and the ambitious purpose to bring the possibility to use and develop space technology to a wider public. With that in mind, Open Cosmos has developed the qbcan, an educational CanSat kit for primary, secondary and tertiary education. The qbcan aims to engage and motivate the next generation of space engineers and scientists.


In case you have any problem during the assembly or operations please post your questions into the qbcan community.

Sensors terminology

BMP180 Pressure and temperature sensor
LLC Low Level Converter
RFM69 433 MHz transceiver

System description

The qbcan bus provides all the required capabilities of a standard CanSat mission: radio communications, a temperature and pressure sensor and a computing platform with a wide range of interfaces. The user can then add extra functionalities (adding sensors and actuators via the provided interfaces) and develop more complex systems.

The main components of the qbcan are:

  • Arduino Pro Micro compatible microcontroller.
  • RFM69HW 433MHz transceiver.
  • BMP180 pressure and temperature sensor.
  • Low Level Converter.
  • Antenna/Yagi antenna connector.
  • Printed circuit board (PCB) that integrates the previous components.
  • Rapid-development software library that interfaces with the transceiver and the pressure and temperature sensor.
  • 9V battery (not included).

The qbcan modular is the smallest qbcan kit with all the components integrated into the same board. This enables the users to maximise payload volume and mass and to be mounted in most convenient section of the CanSat main body. The 0.1 inch header allows easy

The qbcan is compatible with the Arduino programming interface which is open-source and users are encouraged to share their creations and distribute their work.

qbcan interfaces

The qbcan compact contains a wide range of interfaces:

  • Micro-USB connector programming interface
  • Monopole 433 MHz antenna on qbcan option
  • SMA female connector for external antenna on qbcan GS option
  • 32 pin 0.1 inch header:
    • 6 analogue inputs with 10-bit ADCS
    • 14 Digital I/O pins
    • 3 PWM output pins
    • 5V and 3.3V power outputs
    • 5- 12V power input
    • I2C, SPI, UART serial communication ports

The pinout of the qbcan compact 32 pin header can be seen in table and figure below:

32 pin header pin out
Pin number Function Comment Pin number Function Comment
1 TXO UART transmit line 2 RAW 5V min 12 V max power input
3 RXI UART receiveline 4 GND Ground
5 GND Ground 6 RESET Reset pin, connect to ground to reset qbcan microcontroller
7 GND Ground 8 VCC5 5V regulated power output
9 SDA I2C data 10 A3 Analog input pin or digital I/O pin
11 SCL I2C clock 12 A2 Analog input pin or digital I/O pin
13 D4 Digital I/O pin 14 A1 Analog input pin or digital I/O pin
15 D5 PWM or digital I/O pin 16 A0 Analog input pin or digital I/O pin
17 D6 PWM or digital I/O pin 18 SCK SPI clock
19 No functionality 20 MISO SPI master input
21 D8 Digital I/O pin 22 MOSI SPI master output
23 D9 PWM or digital I/O pin 24 A4 Analog input pin or digital I/O pin
25 D11 Digital I/O pin 26 D12 Digital I/O pin
27 D13 Digital I/O pin 28 A5 Analog input pin or digital I/O pin
29 GND Ground 30 VCC5 5V regulated power output
31 GND Ground 32 VCC3.3 3.3V regulated power output

The I2C interfaces are shared with the pressure and temperature sensors, but are also available to the user.


The core of the qbcan is an ATmega32U4 running at 5V/16MH. The microcontroller provides the required computing power to the CanSat and is easy to program using the Arduino integrated development environment.


A RFM69HW 433 MHz transceiver is included to provide long range communication capabilities to the qbcan. The main features of the transceiver are:

  • +20 dBm - 100 mW power output capability.
  • High sensitivity: down to -120 dBm at 1.2 kbps.
  • Programmable output power: -18 to +20 dBm in 1 dB steps.
  • Fully integrated synthesiser with a resolution of 61 Hz.
  • Frequency selectable by software over 256 different channels.
  • 255 possible nodes in every channel.
  • FSK, GFSK, MSK, GMSK and OOK modulations.
  • Hardware 128 bit AES encryption.
  • Over 400+ meters range using whip antennas and several km range using a Yagi antenna on the receiving end.

The transceiver software, included with the qbcan, is interrupt driven (asynchronous response to incoming communications). The antenna of the qbcan compact acting as Cansat is a simple quarter wavelength monopole antenna. The qbcan compact ground station version includes a SMA adaptor in order to connect Yagi antennas in order to improve range and quality of the radio link. Using this transceiver, a qbcan can be used in a CanSat while another qbcan is used as ground station, receiving telemetry from the CanSat (and sending it to a PC via the USB port) and sending commands to the CanSat.

Temperature and pressure control

The qbcan includes a BMP180 barometric pressure and temperature sensor. This sensor communicates over I2C and provides:

  • Pressure sensing range: 300-1100 hPa (9000m to -500m above and below sea level).
  • Up to 0.02 hPa / 0.17m altitude resolution.
  • -40 to +85°C operational range, +-2°C temperature accuracy.


The qbcan can be powered by a standard 9V battery (not included) or a power supply from 5V to 12V. The user has the following power buses available from qbcan compact:

  • 5V regulated power
  • 3.3V regulated power

qbcan compact can supply a total max 500 mA from all regulated buses (current from 5V + current from 3.3V <= 500mA). If more than a total of 500 mA are planned to be used (adding the 5V and 3.3V buses) it is recommended to use the raw battery voltage with its dedicated voltage regulator.


A qbcan software library is included. It provides an easy-to-use interface with the transceiver and pressure and temperature sensors. An example code is provided to speed up the development of the CanSat mission. The library includes a CanSat example and a ground station example.

Getting started

In order to develop software for the Arduino Pro Micro and use the provided qbcan library, the development computer needs to be properly configured.

The following page: qbcan software installation provides a step by step guide to set up the development environment.

In order to complete the software installation, one qbcan is required.

Powering qbcan up

qbcan compact can be powered via USB, 5V-12V power IN or both at the same time. Once power is provided, qbcan compact will start running the software on board automatically.