The thing is, the only tool provided for using the PRU is an assembler[1]. So trying to make an AM335x into an "Arduino" required at a minimum: a friendlier real-time IO system / PRU toolchain, the creation of an Arduino sketch and library API compatibility layer, and circuitry to deal with 5V IO.
Solving all that by just bolting an ATMega beside the AM335x isn't the least bit elegant, but Arduino has never seemed to be too bothered about elegance.
Solving all that by just bolting an ATMega beside the AM335x isn't the least bit elegant, but Arduino has never seemed to be too bothered about elegance.
_1: https://github.com/beagleboard/am335x_pru_package