Recently we have been working on a project to software implentment HCS301 Keeloq encoder on PIC microcontrollers, such as PIC12F629, and the assembly code of transmitter shell is listed as follows.
This code mainly includes the following parts, EEPROM counter increase, Keeloq encryption and PWM transmitting as per HCS301 format.
Other encryption related details can be found at follows.
The actual Keeloq encryption code has been hidden to protect Microchip HCS301 intellectual property, and is only available upon request via email.