Hello Glen, Yes I agree re the STM32F4's DSP capability. It doesn't have proper single cycle MACs. However it's fast and cheap and has float so it does the job nicely. Curiously, no operating system ends up being kinda helpful on a CPU of this size.
I measured 60mA at 3V on the STM32F4, that's the lowest power CPU I have ever played with! I estimated 24 hours operation on a pair of AA's. Plenty. I think if I was doing a multi-channel FreeDV device I'd use .... a PC. Just throw MIPs at the problem. Dead easy to develop on. I/O would be the only hassle. Cheers, David On 21/08/14 07:27, glen english wrote: > indeed Bruce. > > Consider I might be aiming at a portable device, or other low power, low > count silicon platform. (5$) > and bear in mind, I might want a heap processing power left over for > modulator/demod, error correction, some audio processing , noise > reduction etc. > > For those that know real DSPs, they'll recognize that the Cortex M4 > (stm32 4...) is NOT a real DSP. It has some handy instructions, they > call DSP, sure. But start throwing it alot of filtering tasks and you'll > run out of cycles. > > It is a very good general purpose processor though, excellent in fact. > I use it for all sorts of things when I don't care about power > consumption. The CODEC2 is not a simple DSP task, it is much more a > complex algorithm that doesnt get alot of help from a real DSP. The > STM32M4 is not a low power processor. > A real FP processor like the latest low power SHARCs ($10) for similar > money might do the job for less power, depending on the efficiency of > the coder- that's the thing to get the advantage of the real DSP, you > got to know what you are doing. The M4 will make fairly good throughput > out of junk coding. I use the Rowley Associates toolchain. > > > glen english > VK1XX > "yes - I do this for a living" > Altium- ModelSim, Matlab, Vivado, Rowley. > > On 21/08/2014 5:44 AM, Bruce Perens wrote: >> The reasoning is indeed that floating point is easier to develop and >> that our development time is more expensive than CPUs.We don't know >> the table sizes offhand. >> >> However, the assumption that both of the codec and modem would fit in >> really small and relatively low-power floating point chips was >> optimistic and as of this moment it's right on the edge of working in >> the STM32F405 that David has built into his SmartMic project. The >> STM32F405 is an ARM Cortex M4F at 168 MHz, 1 MB FLASH, 126K >> instruction/data RAM, and 64K data RAM. >> >> Over the past weeks David has torn through the code working on >> optimization, and at this moment the receive speed is "borderline". >> >> Thanks >> >> Bruce >> >> CPOn 08/20/2014 11:42 AM, Steve wrote: >>> I think the reasoning is, that floating point and memory are so cheap >>> now, that trying to fit a design into a restricted space would just >>> lengthen the time to profit. >>> >>> Why design to a fixed point $30 DSP when you can buy a $5 CPU with >>> hardware FP. >>> >>> 73,Steve >>> >>> >>> ------------------------------------------------------------------------------ >>> Slashdot TV. >>> Video for Nerds. Stuff that matters. >>> http://tv.slashdot.org/ >>> >>> >>> _______________________________________________ >>> Freetel-codec2 mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> >> >> >> ------------------------------------------------------------------------------ >> Slashdot TV. >> Video for Nerds. Stuff that matters. >> http://tv.slashdot.org/ >> >> >> _______________________________________________ >> Freetel-codec2 mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > -- > - > Glen English > RF Communications and Electronics Engineer > > CORTEX RF > & > Pacific Media Technologies Pty Ltd > > ABN 40 075 532 008 > > PO Box 5231 Lyneham ACT 2602, Australia. > au mobile : +61 (0)418 975077 > > > > ------------------------------------------------------------------------------ > Slashdot TV. > Video for Nerds. Stuff that matters. > http://tv.slashdot.org/ > > > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
