Serial to Bluetooth

When computer makers switched from RS232 to USB, one of the collateral benefits was TTL compatibility with regard to the supply voltage as well as signal levels. Unfortunately, there was also collateral damage, primarily in the form of an enormous increase in the complexity of the data transmission process. All you need for connection to an RS232 serial port is a level converter, but USB requires an extra IC (such as the Cypress CY7C68000 or a special-purpose microcontroller, such as the PIC18F4550) to make data transmission possible.