Sorted out by rule 1 ;-) to avoid this discussion. Anything *optimized* for workstations are unlikely to count as microcontrollers.
Also, timer to do instruction count etc, does not count. It should at least generate a periodic interrupt so you can .
In a way, but I think you can reach a point where there is no doubt that it is a microcontroller. An ATtiny13 with 1kB Flash , 1 timer and 6 I/O's is no less of a microcontroller than an ATmega2560 with 256 kB of flash, loads of timers and serial ports. It is significantly more a microcontroller than an i80386DX
--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may bot be shared by my employer Atmel Nordic AB
I think you mean something like: if it uses less than 1 Watt, runs at less than 200 (or maybe 100) Mhz, has fewer than 144 pins, doesn't have a cache or MMU, has less than 1MByte flash, 1-128KB on-chip RAM, doesn't need external chips other than flash/ROM/DRAM, costs less than $25 then it is definitely a micro controller. You can argue about exact the numbers of course.
Otherwise just about all current ARMs up to 1GHz are "micro controllers" using your definition. Micro controllers typically use small packages, are clocked below 100Mhz and don't cost much. They can't run standard Windows or Linux indeed. High-end processors with MMU, lots of SRAM/cache, with many peripherals (including advanced stuff like audio/video accelerators) are called "application processors".
Just about all CPUs have several serial communication channels, like Hypertransport, USB, Ethernet, JTAG. It would need to be UART, CAN, SPI, or I2C in order to qualify as a micro controller.
All modern CPUs have this, including performance counters. Having a watchdog timer would be more micro controller specific. A low interrupt latency (< 25 cycles) and vectored interrupts are clearly micro controller area too (CPUs with caches usually need a minimum of 100 cycles).
It is more common to have on-chip SRAM than ROM or flash. It would be better to say that it isn't a micro controller if doesn't use flash or ROM to execute most of its code (copying parts of the flash to SRAM for fast execution is OK, using a flash just for booting isn't).
The m32c, amusingly enough, has a single chip mode, a memory expansion mode, and a microprocessor mode. In microprocessor mode, the internal flash is disabled, giving nearly all of the address space to external devices. Single-chip mode reconfigures the CPU bus pins to be GPIO pins.
No, it is the philosophy behind design decisions that disqualifies the parts. I consider a 533 MHz PXA255 to be a (ROMless) microcontroller. It is no less a microcontroller than an 8031. Rule 1 is a sloppy rule, I admit, but it achieve my purpose which is to have a set of rules which, if followed, results in that everything I have a gut feel IS a microcontroller, is identified as a microcontroller.
I do not think MMU, Cache, large internal memory, large pincount disqualifies chips. FPSLIC has 256 pins, and is still a micro. AT91FR40162 (while MCP) has 2 MB Flash/256kB SRAM and is still a micro. ARM9s with cache/MMU still are micros, especially with the new flash based ARM9s coming are still micros. I cant see that if you have two chips, with identical flash/peripherals, and one is using an ARM7 and the other is using ARM946/926, that the first should qual as a micro and not the second.
Maybe, but I think an application processor can be amicrcontroller as well.
No, the high end PowerPCs, SPARCses and x86ses don't. These are Microprocessors. BTW: While Hypertransport may be serial, I do not count bus expansion as a criteria that makes something a microcontroller. Nor do I count On Chip Debugging interfaces. USB/Ethernet I do feel counts.
Performance counters does not count (forgive the pun). If you can schedule a task at a certain time, that definitely increase your "microcontrollerness". Gathering statistics don't.
So the 8051 was not a micro then... No watch dog and at 12 cycles per instruction, I doubt it will fulfil the <
25 cycles. I think these count more as desirable features in a microcontroller, rather than something which decides whether they are microcontrollers or not. A microcontroller can be designed to be fast or it can be designed to be slow. It is OK to be slow, when you are controlling a slow task. An alarm clock, does not need to have very fast interrupts.
ROM
Disagree, the AT76C712 AVR based USB Serial Bridge, I definitely put in the microcontroller camp. It boots from a ROM, copies the application code from a serial flash into the 16-22kB internal SRAM and then runs at 48 MHz from the SRAM. USB device, dual UART, SPI , Timers.
Same goes for the AT91RM3400. Boot ROM, copy to internal 96 kB SRAM. No external bus. loads of serial ports, timers, USB etc. Can't say that is not a micro.
--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
You are both right; what it needs is a qualifier that defines the TYPE of Code memory : Thus we have FLASH uC / ROMless uC ( or FLASHless uC ), or RAMloaded uC, or ROM uC etc.
RAMloaded uC ( and the DSPs that are calling themselves DSCs ) are becomming more common, and Boot from serial memory has rather less design impact than a 32 bit SDRAM bus.
One reason is the poor flash speeds, another is the higher process cost of FLASH, but OnChip RAM for CODE is a valid uC design choice.
Once the CODE fetch at runtime goes (mostly) OFF-CHIP, that's when it shifts => Microprocessor, as then the CODE memory is defined not by the ChipVendor, but by the users design choice.
About here is also when the PCB layers hike, and the EMC testing from all those BUS CODE fetches, become an issue....
Then the 8031 is not a microcontroller. Any set of rules needs to work so that chips generally accepted as microcontroller are shown to be microcontrollers if the rules are applied to their definition.
--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
Rule 1) Anything running late versions of Windows (CE does not count here) is not a microcontroller I am going to ignore all comment about Geode... Rule 2) Anything with a serial communication channel, is a microcontroller Rule 3) Anything with minimum 1 timer capable of providing a periodic interrupt is a microcontroller Rule 4) Anything without internal code memory (cache does not count here) is not a microcontroller Rule 5) Anything without minimum 1 programmable I/O pin is not a microcontroller Rule 6) Anyting REQUIRING a "companion" chip, is not a microcontroller Clarification: A companion chip is defined as a chip which if integrated with a microprocessor would make the microprocessor a microcontroller Exception: A pure memory is not a "companion" chip. ... Rule n) It is a microcontroller
All these will be microcontrollers according to Rule (2) Since rule parsing is stopped when the decision is made, rule (4) is never reached, so all of above will be classified as microcontrollers. I do not see the problem.
If you do not have a timer or a serial port, and no internal code memory, then you are not a microcontroller.
If you have no timer, no serial port, no I/O but do have some internal code memory then you are not a microcontroller.
--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
Doesn't the actual words explain their meaning ? Microprocessor is a device designed to be used for processing data. It is normally biased to have a very high throughput with a large address space for both code and data. A microcontroller is a device optimised to control something, hence it designed to be able to interact with the external world. I/O pins, timers, etc. These days, a microprocessor are often supported by a host of microcontrollers that handels the actual control of needed devices for file storage etc. so that the microprocessor waste as little resources as possible on non data processing tasks. Whether any of these things are internal or external or in multiple devices does not matter. If it is in one physical device, then it is a single chip microcontroller or microprocessor.
As long as one are already discussing something with as many opinions as there are people, why not throw in DSPs into the mix. What makes a DSP a DSP and not a microcontroller or a microprocessor ?
If there are no faster instructions in the architecture than the multiply/accumulate instruction (including the load of data and coeffients) then that is enough for me to call it a DSP. There are DSP microcontrollers and the same rules could be used to differentiate DSP from DSP microcontrollers.
--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
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