On Wed, Nov 16, 2016 at 1:03 PM, Hal Murray <[email protected]> wrote:
> [email protected] said: > > but once you get to most of the ARM processors it is harder to make them > > deterministic because of caches. > > There are many ARM SOC chips that are half way between an Arduino and a > Raspberry Pi. They have GPIO and various serial ports and counter/timers. > They don't have USB, Ethernet, or a display controller. They do have > on-chip > RAM and Flash. > The big divide with ARM is the "A" and "M" kind. The ARM A is what you have inside your cell phone and what is used in the Raspberry Pi and most counters and set top boxes and the like. Typically this run an operating system mostly Linux. The Arm Cortex M is a micro controller. There are different kinds, they are 32 bits and some have floating point hardware, some don't but they are all designed for low power use. You can buy an ARM Cortex M0 on a PCB that is almost as easy to use as an Arduino for about $4.00 shipped. ARM has a huge range of performance, one of mine is a quad core A7 running at 1.4GHz and uses about 1.5 amps of power another is an M0 that runs at 8Mhz nominal but I can make it sleep (stop the clock) and run it off battery power for a long time. The performance range is about the largest I know of The low power Cortex M chips are sized as described below. But the A chips can have a gigabyte of RAM and almost zero flash One reason for this is the at the ARM architecture is licensed to many manufacti=urers and they all need to "be different" > > The ones I worked with didn't have a cache. The on-chip SRAM was good > enough. > > They typically came with 3 sizes of on-chip memory, growing by a factor of > 2 > each step. So you get things like > 16K RAM, 64K Flash > 32K RAM, 128K Flash > 64K RAM, 256K Flash > That was 5-10 years ago, so things have probably changed. I'd be surprised > if something similar wasn't available today. I haven't looked for eBay > style > low cost boards. > > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
