If you need microsecond or nanosecond-level control of I/O, you're probably a little too advanced for an Arduino-type environment.
If you do, the AM335x offers a subsystem called the PRU that lets you program I/O that runs independently from the core. Kind of like, hmm, a bunch of Little Arduinos inside the Big Arduino.
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.
Comments
If you need microsecond or nanosecond-level control of I/O, you're probably a little too advanced for an Arduino-type environment.
If you do, the AM335x offers a subsystem called the PRU that lets you program I/O that runs independently from the core. Kind of like, hmm, a bunch of Little Arduinos inside the Big Arduino.
http://www.ti.com/lit/wp/spry136a/spry136a.pdf
I use my arduino nano to drive 12 servos. This requires microsecond level accuracy. It can be done without too much trouble using the 16 bit clock.
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.
_1: https://github.com/beagleboard/am335x_pru_package
But the reality is that at gigahertz speed you could run the TRE's I/O from userspace and have pretty accurate timing. Just latch your LEDs. =)