[sdiy] dsPIC33 60mips with USB and I2S!

[Eric Brombaugh]

On 07/29/2011 12:38 PM, Tom Wiltshire wrote:
>
> I was attracted by the extra RAM (USB on a oscillator? Pheeerrttt...)

Oh, I don't know. I could think of a few things to do with USB that 
might make sense in a modular context. Even an oscillator...

> but it sounds like I'd be better off using external serial RAM with one of the current 40MIPs dsPICs.

The lack of SRAM in the dsPIC is becoming more of an issue. I did a 
little board a while back that uses one of those 32kB SPI SRAMs but even 
that is pretty limited - the access latency and small size makes it 
pretty marginal for stuff like delay buffers.

If I had my druthers I'd like a part with these features:

* Flash program store - up to  256kwords
* 32-bit native data
* True DSP (single cycle MAC, separate prefetching operand buses, zero 
overhead looping, etc)
* I2S interface
* Minimum 8k on-chip SRAM
* External SDRAM interface.
* 12-bit ADCs
* Minimum 100MIPS

Apparently that's too much to ask - no one out there is doing anything 
like this. TI's Piccolo DSCs are about on par with the dsPIC, the ARM 
Cortex M4 doesn't appear to have what I'd call true DSP capability and 
all the higher-end TI and ADI DSPs require external peripherals and 
flash. Drears.

Eric