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Putting the project on hold

A project log for carbt_v1

[DISCONTINUED] An inexpensive bluetooth music system for cars with lacking stereos.

hybridairHybridAir 10/30/2015 at 22:080 Comments

I will be putting this project on hold for a few months, from now to mid-February 2016 probably. I have another more time-sensitive project that I need to begin working on, which I will be posting here shortly. Make sure to keep an eye out for it!

I have been continuing to make progress on this project as usual, albeit rather slowly. Since the last update, I have been working on the ODB2 integration, and have added a buzzer to the display module for audio feedback. The setup I had to use for the buzzer is kind of unusual. Due to the ATTiny44's PWM limitations, I could either have 2 individual fixed-frequency PWM channels, or a single variable PWM/frequency channel. Since I am already using PWM for the lighting, I instead had to use a 555 to create the variable frequencies for the buzzer. I am only able to get 3 distinct tones out of it though, since using the other available PWM channel to control the 555 output frequency was too unreliable. To get those 3 tones, I am toggling two outputs which go through some resistor dividers, and then to the 555 control voltage pin. It isn't much, but I made a short video showing some basic functionality.

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