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Visible Light Transceivers Based on PIC12F508

2014-12-23 19:32  
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The PIC12F508 device from Microchip Technology is low-cost, high-performance, 8-bit, fully-static, Flash-based CMOS microcontrollers. The PIC12F508 employ a RISC architecture with only 33 single-word/ single-cycle instructions. All instructions are single cycle (200 ìs) except for program branches, which take two cycles. The PIC12F508 device deliver performance an order of magnitude higher than their competitors in the same price category. The 12-bit wide instructions are highly symmetrical, resulting in a typical 2:1 code compression over other 8-bit microcontrollers in its class. The easy to use and easy to remember instruction set reduces development time significantly

PIC12F508 Application Circuits

PIC12F508 Appication Circuit

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In  (Fig. 1), a PIC12F508 microcontroller is used to generate a 40 kHz clock which is passed to the one-shot IC DM74121N. The TX signal from the USB-MB5 is then pulse-position modulated (PPM) by the one-shot device 74121 before being transmitted out through the LEDs.
    The receiver consists of a Centronic OSD50-E eye-response photodiode, a preamplifier KA2181, a phase-locked loop MM74HC4046N, and an inverter 74LS04. Light signals received by the photodiode is preamplified and shaped by the preamplifier before being demodulated by the phase-locked loop. For the KA2181 circuit, the user must find its optimal inductor value which determines the receiver's sensitivity.