Arduino on a breadboard and SD card reading



After a few evenings working on the PIC (slave) end of things, I decided to return to the Arduino (master) development.  Having learned lots about PIC circuits and development I decided to learn some more about Arduino, I did this by building one on a breadboard.

Building the "bare-bones" Arduino on a breadboard was very easy, only a couple more connections than the PIC.  Uploading a rogram however was slightly more complicated as this is done using a serial connection. I purchased a "USB 2.0 TO RS232 Converter UART TTL Serial CP2102" from eBay for a few pounds and set about wiring onto the breadboard.

The instructions for the converter showed that I had to solder a DTR connection onto the card to enable programming of AVR chips (auto-reset), so this was easily done.

I was able to test the basic serial connectivity, but failed to upload a program to the ATMEGA chip. After an email to the seller I realised that, despite normal convention, the connections for this stick are RX->RX and the TX->TX ? very strange. I saw several postings on forums slating people for even suggesting that this is the case on some cards ! Well I can confirm that if you encounter a stick labelled "BAITE" (www.betemcu.cn) you need to wire RX->RX and TX->TX otherwise you won't be programming anything ;)

Breadboard Arduino
The next investigation was to connect an SD card to the Arduino so that I have somewhere to store the lighting patterns. I have had the SD card module for a while but not tried to connect it. The first attempt hung with nothing output to the serial port, this turned out to be due to some initialisation lines in the 'setup()' method that wait for the serial to be ready on a Leonardo, well I don't have one of those so I commented them out and,surprise surprise, it all worked :)

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