USB Interface Based 8051 Microcontroller

USB Interface Based 8051 Microcontroller

The project was designed as USB interface with the use of a microcontroller known as Cypress CY7C68013 that is based on 8051 processor.
Explanation

Aside from being a USB interface, the 8051 processor contains several special functions and built-in peripherals. This interface card would provide an easier connection to the controller of other electronics while holding some necessary components like crystal and voltage regulator. The available packages are designed for industrial mounting which makes the soldering of components a critical part.

This simple circuit contains the controller, a crystal with two capacitors, two LEDs with series resistors, some decoupling capacitors, a voltage regulator LE33, an I2C serial EEPROM 24C64, and a type B USB connector. The crystal capacitor should be 10pF instead of 33pF since their value was rather critical.

The circuit can be used as general PWM charger for NiCd and NiMH cells by making a current flow through the cell in reverse direction. The battery will become fully charged when about 150% of the cell capacity has flown through the cell. Since the charger works with PWM, it outputs short pulses of about 1.2A. The charger is based on Atmel AT90S2313 microcontroller.