Main features: 2 frequency generation 800 + 1000 Hz or 400 + 2600 Hz, unique frequency generation of 1000 Hz, Min. 100 mV cc sur 600 Ohm, soit 35.4 mV eff. monofrequency or 25.0 mV eff. en 2 tones, Pure spectral 0.3 and 150 kHz support. Up to 50dB, Distortion inf à 0.01% (single frequency), fed with a 9V stack, consumption of 8 mA and 50 hours of operation with an alkaline stack.
Common 2 frequency difference in 800/1000 Hz or 200 Hz mode, or in a multiple input mode in a 400/2600 Hz pair. The signal rotates up to a maximum of 5 ms. To save a simple assembly, the eprom is addressed in binary mode and logic is the most critical outcome. The frequency required for a 14-bit divider, quartz is 3.2768 MHz, which is the optimal standard value for use.
The main features of this assembly are :
– Generation 2 frequency 800 Hz or 400 + 1000 + 2600 Hz ( by moving a jumper)
– Generation of a single frequency of 1000 Hz
– Adjustable output level of a min level . 100 mV dc 600 Ohm 35.4 mV rms . in single frequency or 25.0 mV rms . 2 tones
– Spectral between 0.3 and 150 kHz sup Purity . 50dB
– Distortion lower than 0.01 % (by SFN )
– Powered by 9V battery consumption 8 mA or 50 hours of operation with alkaline battery .
– Switching automatic switching PTT .
Principle of Operation
How does a DDS?
In its simplest form, a DDS consists of a precision oscillator , an address counter , a prom containing the code and (analog digital / ) D / A converter . This is the solution that was chosen for this description.
Unlike the two frequencies generated mode 800/1000 Hz is 200 Hz or multiples in the case of the couple 400/2600 Hz signal is therefore renews at most every 5ms . To retain its simplicity in assembly, EPROM is addressed in binary mode and the software is written accordingly. With a 14-bit divider , the necessary crystal frequency of 3.2768 MHz is , which is fortunately a standard value .
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Published: 2008/06/23 Tags: microcontroller projects
PIC17C77 Midi Control Circuit MC14067
There a few years, PC began to be powerful enough to réaliserde software synthesis. For my part, I discovered the real time software synthesis with ReBirth on my Pentium 166MHz MMX. Of course, software synthesis exist on the PC, such as Virtual Waves, but the arrival of real-time creates a turning point for me anyway. At the same time, he created a new need.
to remain general, the main objective is to provide MIDI signals function 15 knobs. More specifically, the 15 faders knobs will be scanned by a multiplexer, itself controlled by a microcontroller Microchip PIC16C77 which will at the same time take care to do the AD conversion. As soon as he finished the conversion to digital, it compares the value obtained with the old value that was stored in memory, and if it has changed (so if the knob was turned) it will transmit the new value in accordance with the MIDI protocol. Three bytes are transferred (channel number & type ‘Control Change’ – controller number – value of the controller). So much for the outline. In fact, the program is a little more complex, for example, I use a small