I'm building small ROV with 4 brushed motors, converted from bilge pumps with 3D-printed props and mounts. I'm looking for controlling system, and I'm thinking if ardusub on Raspberry Pi will work for me. I have very limited budget, so 15$ brushed RC ESCs seems bit expensive, when I can control 2 motors with < 5$ L298N H-bridge board ( http://www.dx.com/p/l298n-dual-h-bridge-stepper-motor-driver-module-w-heat-dissipation-for-arduino-red-white-408436#.WPZMh1OGNYg )
This works fine with Arduino, using 3 gpo-pins per channel. At the moment I think the easiest way to use these will be using arduino as i2c slave and put it in place of PCA 9685 in PXFmini-clone http://diydrones.com/profiles/blogs/mini-zee-a-100-diy-smart-drone-with-the-pi-zero-and-apm?id=705844%3ABlogPost%3A2215516&page=11#comments
Another option will be modifying the output code so pwm will be 0-100% instead of RC and few pins are used for direction, 0 or 100% out.
Have someone already made something like this?