Ses kayıt devresi pic16f876a mikrodenetleyici üzerine kurulu ek olarak bir kaç pasif komponent ile devre kurulmuş sd kart üzerine kayıt yapabiliyor stop, play, record, pause fonksiyonları var pic16f876a 2 numaralı bacağından ses girişi yapılıyor ek olarak preanfi ile mikrofonda bağlanabilir.. Ses kayıt devresine ait kaynak PIC C ve hex kodları var.
PIC16F876A SD CARD SOUND RECORDER PIC16F876A’s ADC digitises the sound and store it in the SD card (not SDHC). The PIC’s CCP is used as a DAC to convert the digital data back to audio. The sound is converted to 20KHz 8 bits mono in a format similar to *.wav files. The quality of the audio is reasonable. SD card interface the PIC in SPI mode. Reading and writing data is in multi-blocks. Memory is used at the rate of 20KB/s. The Error LED indicates error sent by the SD card. The software doesn’t use any file system, it just uses absolute memory addresses (raw). Since the programme is less than 680 bytes there is much resources left for adding features. Audio input is 1Vp-p , you can use the mic circuit or other source. The CCP in PWM mode gives 20KHz wave with duty cycle modulated to the audio amplitude. A low pass filter removes the 20KHz component. I added a simple 2 transistors amplifier to boost the power to drive 32 Ohm speaker or headphones.
File will compile with the free Hi-Tech C compiler. Recording is done by the ADC using only the LSB. Bytes are written to the SD
at the rate of 20KHz. It is similar to the format of .wav sound files. For playback CCP is used as a DAC (Digital to Analogue Converter).