Re: Modular uBitx - "Ex: Harmonics"

Jack, W8TEE

Our goal with the JackAl board is to give enough memory resources and horsepower to let the hacker run wild. We also bring out on the board 12 unused I/O pins to play with. (There are some unused pins "under the board", too.)  The display uses the SPI interface and all of the video processing is on the display card, so it's not sucking cycles away for screen updates.

The critical bottleneck is not the flash memory, it's the SRAM. That were the stack and heap space come from...where you data live. Some Nano users think that, when SRAM is at 75%, there's still a lot of memory available. Not so...that's a compile-time statistic and it's static. Because every function call pushes the stack deeper and deeper at runtime, what looks like a lot of available memory at compile-time results in disaster when the stack crashes into the heap space. With a Nano, all of your data plus the stack must fit in 2K of SRAM. Compare that with 256K of SRAM on the Teensy.

What Allard and Dr. Lee have done with the Nano is truly amazing. Me? I'm not that clever, so I need more elbow room and the Teensy 3.6 makes that a pretty nice environment to work in.

Jack, W8TEE

On Tuesday, August 14, 2018, 9:09:12 PM EDT, Nick VK4PP <nickpullen@...> wrote:

Hi Jack, 
Thanks for the ideas.
99.99x99.99 for board size.
I was thinking maybe the Arduino Nano 2560 Mini Pro, About $13... lots of IO...
But then, with the nano, when using I2C, there are 6 extra IO ports. Its just program memory...
I did want to limit FW changes, I was hoping to only have to change the code relating to LPF and BPF...
I'm thinking 5 LPFs and BPF that are switched in. Builder selects the 5 bands they want to operate on and builds the radio/software for that...

The more I think this over the bigger it becomes.

Farhan has achieved so much already! I would only do stuff if he was OK with it,


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