Pure C Arduino

This post is an addendum to the previous one. To make our lives (as a software developers) even more easier it is possible to recreate a real audio without even having to built the R-2R ladder. Atmega328 comes with a PWM capable timers and they're good enough to produce audio quality analog signal. PWM fundamentals I'm not going to go into details about PWM digital to analog conversion, on this blog I focus on my code and do not intend to cover the theoretical background very thoroughly. Please take some time and familiarize yourself with the PWM theory explained on those sites: Open Music - PWM DAC Open Music - Dual PWM Open Music - Distortion Analysis Open Music - PWM Tutorial In general every PWM DAC can be described by a PWM frequency - f pwm (the frequency of the squarewave generated - which is constant) and the PWM bit resolution - bitres (which describes the granularity with which we can control the duty cycle). All of three Arduino's...

There is a lot of projects out there which use  R-2R ladder and an Arduino to recreate sounds from either SD card or short audio clips programmed directly to MCU's flash memory. Although using SD card is fairly reasonable and provides a lot of flexibility it's not very challenging (from the software point of view) and it requires some additional hardware. Believe it or not we already have all the needed hardware in the Arduino itself. Assumptions In this project I'll play mp3 or any other multimedia files from the PC using Arduino. Bellow are the details: Play PCM 8kHz 8bit Audio with Arduino Audio samples will be transfered via USART from the PC in binary format using SLIP Audio files will be decoded on the PC side and only the RAW data will be send to Arduino Timing Arduino is a powerful machine, powerful enough that it's possible to play audio with even higher sampling rates and bit-resolutions than assumed above, the bottleneck in this...

It's time to do something useful with our small 8-bit computer. Music box is a fun and easy project. It's not demanding from the hardware point of view but it can be a little bit tricky from the software point of view itself - ideal project to learn a lot and not to spend the whole day soldering. What we will need:  an Arduino (of course)  Piezo buzzer  ... and that's all. Now a couple of words of what we want to achieve.  Requirements  Let's point them out: play monophonic melodies by generating tones (1 channel MIDI instrument) the notes will be send by the PC through the serial port  our musicbox should be visible to the PC as a MIDI port  be able to use MIDI player of choice on PC to play MIDI files on our musicbox  The requirements are specified. Unlike most of the simple projects around which play the same melody everytime, which most of the times is hardcoded in the program memory and in order to change it...

A word of warning, this post will be kind of long. I will try to cover the binary communication over serial port basics in 2 languages (C & perl), but I hope every one will bare with me until the end. I'm almost ready to go into some of my "real" projects. In order to do that all that needs to be done is to talk a little about SLIP protocol. SLIP protocol is used to synchronize data between receiver and transmitter on a serial line (not only RS232 , ethernet as well and many other mediums). SLIP is one of the most commonly used option, the other one is Modbus RTU , which describes some timing constraints and requirements during the data transfer. I haven't tried Modbus RTU yet, since SLIP is doing pretty good job for me.  First of all why do we need to synchronize the data at all and what does it mean in details in the first place ? The reason for that is simple (maybe not so obvious in the first place). Consider the following situations: We want ...