Motor Drivers

[techhelpbb]

Originally Posted by apalrd

The propeller has basically no peripherals. While that gives you a lot of flexibility in code, there are some things that should stay peripherals.

I work professionally with a MPC5600 series processor, which has a lot of peripherals. The eTPU (Time Processing Unit), eMIOS (Modular Input Output System), and DMA (Direct Memory Access) alone on the chip I am currently working with would take around 192 propeller cogs to get something close in functionality, and the TPUs also additional peripherals to synthesize clocks (e.g. angle clock/angle timestamp) and manage timestamps/clocks that would have to be replicated somehow. This dosen't include SPI, QADC or the actual PowerPC itself. While you could likely move some of the algorithms into the cogs that deal with the IO, you would basically need over 200 cogs to get the low and some mid-level software done, and we haven't even touched comm, OS, or high-level application code.

A good C compiler is basically a requirement for an embedded platform these days, especially with autocoding tools which generate C code from models.

I can't speak for the cog count you've assigned to these functions but realistically if you really need purpose built peripherals there are many choices to achieve that result. For example I had no trouble at all gluing a Xilinx CoolRunner CPLD or Spartan 3 to the Propeller and I have a rough prototype using the XCore. More importantly I could change the glue to multiply the number of CPLD/FPGA connected to one or many cogs or Propeller chips. (Interestingly the prototype for the Propeller was made in an FPGA).

Realistically speaking if we can compare the Parallax Propeller 1 to the cRIO which includes the FPGA it's only fair to consider the inclusion of similar hardware.

Also there are OS for the Parallax Propeller.

I can't argue that you should back-hand your way to the sort of integrated functions you enjoy on your microcontroller / microprocessor of choice if you don't have some other reason to do it. Surely if those peripherals are your highest priority you'd be foolish to try to round the square peg to fit that hole. Especially if those peripherals are some kind of proprietary IP.

Still I can drive a FIRST robot on a single Parallax Propeller and it would be sort of like the performance of a bunch of the old IFI control systems.