As the bootloader solution of Arduino proved as problematic with young children I tested several different solutions. One is to use a cheap serial programmer to program Arduino via ISP programming. Unfortunatly Arduino relies on uisp that does not support newer version of the sdk500 firmware or usb programmer that is why I could not use the Atmel original hadrware. I used an avr910 and changed the preferences.txt and set upload.erase=true, upload.verify=true and serial.download_rate=115200 as written on the Arduino website. Also upload.programmer had to be set to avr910. A crucial point is (especially when using an usb-serial adapter) to set the Comport number between 1 and 4. Using the external programmer we could simplify the board further.
Arduino uses the 6-pin ISP while the programmer (if you buy a ready-made one) uses 10-pin – you need an adapter.
After checking and discussing the observations of our workshop we have the most important problems to fix on the hardware as the following:
Make the transfer of the programs to the chip more stable
Fix the cables at the boards
The first problem is not easy to solve. The Arduino bootloader system work but it is not very easy to press the buttons at the right moment. Therefore we experiment with other solutions: using regular programmers to upload the sketches. The cheap parallel programmer proved as an unstable solution therefore it is no need to explore it further. It works but we somtimes had to erease the chip a couple of times tu brun new programs to it.
Also parallel interfaces are not found anymore on newer notebooks. We tried to use the SDK500 directly from Arduino but UISP seems to have a problem when the SDK500 has Firmware from 2.0 on. UISP also cannot work with USB programmers as the MKII. Our last hope to work with UISP is a cheap serial programmer we can get here.
To fix the cables in a more stable way we can use pin connectors with cables soldered to them, we will also try out various connection systems on the market as it is a lot of work to make the connections manually.
To ease the circuits with resistors and actuators we wanted to but the resistors and actuators on fabric and having color coded connection to the controller. I just finished to make prototypes to verify the circuits. Here are the schemes for switch, sensor and led.
And that is how a patch could look (only from the technical point of view )