Tag Archives: arduino

SD Card Writing with the Minimus32

Part of a project that I am working on to measure the temperature and log it, involves writing to an SD Card (reading from it is not so important). So as part of this I purchased some items from the Proto-Pic website, one of which was an SD Card breakout board which came with, as a new person to this, I felt, next to no direct guidelines or instructions on how to wire it up. Sure, there’s schematics and the SanDisk pin-outs. However, nothing particularly clear as to what, connects, to what.

Paul Brook has on his wiki, the pin-outs for the Minimus32 which clearly shows the SPI (that’s effectively how to communicate over serial) but translating this to the break-out board was troublesome. However, after trial and error and running out of memory, I discovered the following works:

SCK /10 -> CLK

SS  /9  -> D3

MOSI/12 -> CMD

MISO/13 -> D0

The first problem I had to overcome was the fact that the Minimus32 has 1k of RAM to work with, some of which is used up by variables, ,code running, etc. This was exasperated by the fact that the library I was using to talk to the SD Card, attempting to use FAT32, was quite bulky.

Thankfully, there is an alternative, FAT16 based library that claims to take up much less memory. The difference? This means that really, I can’t write gigabytes of data to an SD Card. When all I’m doing is logging temperatures, I don’t need that much data.

This FAT16 library requires a bit of hacking to get to work with the Minimus32, it requires a profile for the AVR_AtMega32u2 else it cannot identify the chipset, this is so that it can set the aforementioned PINs properly (I think it’s in SDCard.h in the library, which you put in the sketchbook/libraries/Fat16 folder) and be able to communicate with the SD Card.

In fact, it was this library, which because it was smaller and wrote out to the Serial (monitor-able using the Arduino IDE or HyperTerm or equivalent) gave me an error code which let me work out which cable I had connected incorrectly. (I had the CMD and CD connections crossed on the break-out board).

Damn I was joyous.

Electronics at Leeds Hackspace with Arduino and Minimus32

Update: While this version of the Arduino IDE will work, I have attempted a way of getting the latest version.

Within the past few months I picked up a new hobby, my friend Kai mentioned this place to me once before and I’ve always had an interest in electronics so off I went to the Leeds Hackspace.

To prototype electrical, let’s say, gadgets there is a device called the Arduino which with a little bit of C++ programming, some wires, LEDs, buzzers, chips, etc. You can get up and running into a large or small system to do almost whatever you want.

Typical applications involve constructing an autonomous robot to controlling laser cutters. Lasers are fun.

So along came this device, called the Minimus32 which, I’m told, was originally intended for circumventing the copy protection on the Sony Playstation 3. Turns out, however, that this little device uses the same chipset as an Arduino and can run the same code and behave in the same way, especially when it has been flashed with a new DFU Bootloader. The best part about this, is that the Minimus32 is typically about a fifth the price of the equivalent Arduino (possibly Leonardo model).

To get this to work under Linux is quite straight forward (at least within Debian and Ubuntu). You use the Arduino IDE 1.0.1 and you grab the profile information for the board from Paul Brook‘s github repositories which allow you to upload the code and monitor the serial port. It also interprets some of the default pin-outs and Paul also has a slightly re-worked OneWire library to use the internal pull-up resistor on the board.

When it comes to Windows, however, it gets a little bit tricky.

As it turns out, the latest Integrated Development Environment (IDE) for Arduino comes with an ‘avr-gcc’ compiler, which handles the compilation of the C++ code. However, in the windows bundle from the Arduino site this is grossly out of date. When this is combined with Paul’s hardware profile for the Minimus32 and a flashed Minimus, the compiler doesn’t know what to do with it.

Fortunately, I have scoured about, packaged together the IDE, a ‘sketchbook’ folder (where the hardware profiles/libraries are stored), an updated WinAVR compiler along with a recently compiled avr-gcc compiler (c/o Andy Brown). If you do not change your Arduino IDE preferences to use this sketchbook folder, you will not be able to select the minimus32 as your board (which is required).

I’m happy to say, that using the drivers supplied with the latest Arduino IDE for windows (1.0.2) along with the updated compiler and Paul’s hardware profile I’m quite happily compiling and working with the Minimus32 on windows (version 7, 64bit). Oh, and Paul’s hardware profile also include the DFU Bootloader to turn the Minimus32 into an Arduino.

Download: Arduino IDE 1.0.2 for Windows with Compiler + Paul’s Profile / Library (98mb)