Inroduction
More and more experiments are now ‘PC-assisted.’ Also conventional acquisition systems are very expensive. Since portable PCs are today common and a USB link is a better solutionhere we present an oscilloscope using USB port of the PC that operates at up to 10 kHz with ±16V input voltage. It has much more improved features than the PC-based oscilloscope . The oscilloscope uses IC PIC18F2550 from Microchip as the main controller, which makes the oscilloscope compact as there is no need of additional power supply for the entire circuit board.
Circuit description
At the heart of this oscilloscope is USB2.0-compliant microcontroller PIC18F2550 from Microchip. You can also use IC18F2445 in place of PIC18F2550. Specifications of this microcontroller are:-
Features of 18F2550
Programming
1. Up to 32 kB of flash memory, 2kB RAM and 256-byte EEPROM
2. Extended instruction set (optimised for ‘C’ compiler)
3. 8x8 single-cycle multiplier
4. Single-supply serial programming and easy debugging
USB transceiver
1. USB1.1 and 2.0 from 1.5 MB/s to 12 MB/s
2. Isochronous, bulk and interrupt transfer modes
3. 1 kB of access RAM usable with 32 endpoints (64 bytes each)
Multiple oscillator and power modes
1. From internal 31 kHz to external 48 MHz with PLL
2. Possible software switching between ‘run,’ ‘idle’ and sleep
modes. In sleep mode, current is down to 0.1 μA.
3. Wide operating voltage range (2.0V to 5.5V). Useful for battery
operations.
Complete set of classical peripherals
1. Several input/output (I/O) ports, four timers with capture/
compares
2. Synchronous and asynchronous enhanced modules
3. Streaming parallel port
4. 10-bit ADC module with up to 13-channel multiplexer.
This microcontroller has a USB2.0-compliant transceiver and a CPU running up to 12 MIPS.
