Raspduino

The Raspduino V1.1

This is the documentation page for the BitWizard Raspduino board. The Raspduino is an Arduino compatible microcontroller board, designed to plug on top of a Raspberry Pi (some people like to call this a Pi Plate). It is then possible to add Arduino shields to the Raspduino.

The Raspduino can be bought in the BitWizard shop.

Features

• Fully Arduino compatible
• Plugs directly on a Raspberry Pi
• Compatible with (almost) all Arduino shields
• Equipped with an ATmega328 microcontroller
• Upto 8 analog inputs
• Upto 20 digital I/O
• Breaks out the Raspberry Pi's SPI and I2C busses

Software Installation

Using the Arduino IDE

Running the Setup Script

To be able to program the Raspduino with the Arduino IDE, you will have to add the board and the Raspberry's serial port to the arduino interface. We have created a script that will automatically apply all settings to get you going. You can get the script here.
Once you have installed the Arduino IDE, run this script as root (hint: use sudo), and you should be ready to go. You might have to reboot the Raspberry Pi to apply the settings.

If you're not familiar with linux, these are the commands you can use:

wget https://raw.github.com/rewolff/raspduino_tools/master/raspduino-setup
sudo ./raspduino-setup
sudo reboot

Uploading a sketch

If you have run our setup script, this should be pretty easy. Start up the Arduino IDE on your Raspberry Pi, select the /dev/ttyS0 serial port, and the Raspduino board (currently the bottom one), and hit the "upload" button.

Using PlatformIO

Setup

PlatformIO is a cross-platform code builder and project manager. It is mostly aimed at embedded development. PlatformIO can be run on an Raspberry Pi to program the RaspDuino. The main advantage is that you write both Arduino Wiring code and AVR native code. Also, it is command-line only, which is a plus for a headless Pi.

First, the serial console on /dev/ttyAMA0 should be disabled. If you dont know how to do so, run the script For setting up the Arduino IDE.

Secondly, we need to install pip, the Python package manager. Since the version in the Raspbian repos is too old, we need to install from the internet:

wget -O- -q https://bootstrap.pypa.io/get-pip.py  |sudo python -

For more information about pip, refer to the homepage.

Next install PlatformIO and SCons:

sudo pip install platformio && sudo pip install --egg scons

Next, download the toolchain and programmer (this could take a while):

sudo platformio install atmelavr

Your Raspberry Pi is ready to compile and program the RaspDuino!

Creating a Project

Create a new empty directory:

mkdir myproject

Change into the newly created directory:

cd myproject

And initialize a new project:

platformio init

The project configuration file "platformio.ini" and a folder called "src" are created.

Edit platformio.ini to look like this:

[env:atmelavr_raspduino_board]
platform = atmelavr
framework = arduino
board = raspduino
upload_port = /dev/ttyAMA0
# enable auto-uploading
targets = upload

Running the Project

Put your source files in src/ and run

sudo platformio run

It should compile and program the RaspDuino. An example main.c written in Arduino Wiring can be found here. An AVR native version is also provided. More can be found among the project examples. platformio.ini has to be modified in all cases to work with RaspDuino.

Connectors and pinout

The Raspduino of course has the same connectors and pinout as a regular Arduino, and some extra connectors.

Arduino headers

These are fully compatible with other Arduinos and Arduino-compatible boards. We extended the second digital connector just like on the Arduino Uno, and added the SCL and SDA pins. These are wired in parallel with Analog pins 4 and 5.

Raspberry Pi connectors

The Raspberry Pi has two SPI busses, and one I2C bus. Those are (just like on our Raspberry_Pi_Serial board) broken out to their respective headers, labeled as SPI0, SPI1, and I2C. The signals on these busses are 3V3, but the inputs are 5V tolerant. With the 3V3/5V jumper, you can control what supply voltage is delivered to these connectors. The default setting is 5V.

Power input

It is possible to connect an external power supply on these pins, in case you want to use your Raspduino without a Raspberry Pi.

Extra analog connector

The RaspDuino has two extra analog pins (A6 and A7) provided on an extra connector located near the analog pins. The connector also provides ground and 5V (or optionally 3V3).

1	GND
2	Analog6
3	Analog7
4	V+

LEDs

The Raspduino has two LEDs: A power indicator, and a LED connected to digital pin 13.

Jumpers

The Raspduino has a number of jumpers, to configure it for multiple different scenarios.

ICSP/SPI jumper

It is possible to use this connector as an ICSP connector for the AVR, or an SPI connector. By default, this connector is configured as an ICSP connector, but by cutting the trace between the ICSP pad and the center pad, and shorting the center pad to the SPI pad, this connector can be used as an SPI connector. For example to control one of the BitWizard SPI expansion boards from the Raspduino.

I2C jumpers

It is possible to connect the Raspberry Pi's I2C bus to the I2C bus of the AVR. To do this, you need to short the SCL and SDA jumpers with a solder bridge.

Serial busses voltage selection jumper

The 3V3/5V jumper next to the Raspberry Pi connector controls the voltage supplied to the connectors that break out the Raspberry Pi's SPI and I2C busses. It is possible to run these busses on 5V or 3V3. 5V Is the default setting, but by cutting the trace between the 5V pad and the center pad, and connecting the 3V3 pad to the center pad with a solder bridge, you can set the supply voltage to 3V3.

AVR voltage selection jumper

It is possible to run the AVR on 5V or 3V3 when the Raspduino is connected to a Raspberry Pi. The default setting is 5V. To set the AVR voltage to 3V3, cut the trace between the 5V pad and the center pad, and connecting the 3V3 pad to the center pad with a solder bridge. Officially the AVR cannot run at 16MHz with 3.3V supply. In practice we haven't seen any problems with running it at 16Mz on 3.3V.

Powering the Raspduino

You can power the Raspduino in two different ways; By the Raspberry Pi it is plugged into, or if it is used stand-alone, you can connect an external power supply to the "External Power" connector. The supply voltage should be between 7 and 15V. If the voltage is higher than 5V, it will be regulated down to 5V.

Future hardware enhancements

Suggestions are welcome.

Changelog

1.1

• Initial public release

Useful links

The Raspduino BitWizard shop page