[sdiy] Using Cortex Mx Arms in Synth DIY

[James Patchell]

     Yep, slow access to the IO pins is a big problem on some of the 
ARMs, I have experienced that first hand.  What is funny is if you have 
a chip with an external bus interface, you can make your own IO ports in 
a CPLD or FPGA, and you can toggle the bits just as fast as you would 
expect.

     I haven't been able to look at the raspberry Pi because something 
on that web page in combination with my screen reader makes my computer 
crash.  I am going to upgratde the screen reader in just a couple of 
days, hopefully, that will allow me to "look" at that webpage.

-Jim

On 12/23/2011 11:59 PM, Paul Maddox wrote:
> James,
>
>>     The Cortex Mx processors are:
>>     1. Very Inexpensive
>>     2. Very6 FAST!
>>     3. Free Developement  Tools?
>>     4. Easy to use?
> 5. Have slow IO.
>
> last I looked you couldn't access the IO on some of the devices as fast as the chip could run, for example the philips LPC series, I can't recall where I saw it but the IO would only run around 12Mhz, I real shame if you want to use some 20Mhz SPI.
> I've been looking at the XMEGA range, which is a step up but I wonder if I'm just delaying the inevitable.
>
>
>>     The main problem is the development tools.
> yep, always has been sadly....
> But what about GCC?
>
>>     For debugging and programming, JTAG interfaces can range from basically free to quite expensive.  I have a J-Link that came with an Arm dev kit.  I*f you buy the JLink by itself, it can be quite pricey.  There is an open source JTAG interface that uses an FTDI chip.  These are fairly reasonable, but I don't know how difficult it is to get one to work.
> good question
>
>> Anybody Elese have any thoughts?
> I'm considering swapping to something a bit more beefy for some of my projects, I love the AVR dearly, but 20Mhz with 2K of RAM is starting to get limiting.
> I'm considering getting something like the raspberry pi for developing ;
>
> http://www.raspberrypi.org/ (currently down for some reason)
> http://en.wikipedia.org/wiki/Raspberry_Pi
>
> which gives me a linux based OS, running from an SD card and enough GPIO to cover things like a UART for MIDI and SPI for writing to an FPGA/DAC/ADC/Memory.
>
> This also avoids the need for costly ARM dev kits, I can use GCC to write for linux.
>
> I'd like to use more ARM stuff, but the compilers are very pricey.
>
> Paul
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