Author Topic: 8-bit uC - is there even a point?  (Read 24499 times)

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Online wraper

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Re: 8-bit uC - is there even a point?
« Reply #100 on: September 28, 2018, 05:41:58 pm »
$70 cents on 1000 units is $700 dollars. On average little over 1 days worth of engineering time. One of the things I've learned over the years is to start looking at component costs at much higher volumes than 1000 units. However it is good to put a lot of thought into production. Again looking at component costs only can severely hurt your business if a product take too long to program & test.
70 cents here and there. I don't think one will limit not caring about expenses to MCU only, in the end will end up up with 3-5 times more expensive BOM.
 

Offline nctnico

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Re: 8-bit uC - is there even a point?
« Reply #101 on: September 28, 2018, 06:15:55 pm »
$70 cents on 1000 units is $700 dollars. On average little over 1 days worth of engineering time. One of the things I've learned over the years is to start looking at component costs at much higher volumes than 1000 units. However it is good to put a lot of thought into production. Again looking at component costs only can severely hurt your business if a product take too long to program & test.
70 cents here and there. I don't think one will limit not caring about expenses to MCU only, in the end will end up up with 3-5 times more expensive BOM.
You are making the same mistake as many others: you don't care about engineering time!
I know saving a few cents from the BOM gets you an 'atta boy' quickly because it is easy to visualise. However in many projects simple costs savings end up to become huge time sinks. If you need to spend a few weeks to try and optimise code because of a silicon bug, too litle memory or lesser performance in a cheaper microcontroller you'll end up losing your bosses' money. And it is not just development time but also the sales start later. Not to mention the time could have been spend on the next product.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline langwadt

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Re: 8-bit uC - is there even a point?
« Reply #102 on: September 28, 2018, 07:27:29 pm »
I'm sure you can run it bare-metal as well.

I'd assume you can run a barebones binary from uboot
 

Offline donotdespisethesnake

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Re: 8-bit uC - is there even a point?
« Reply #103 on: September 28, 2018, 07:34:55 pm »
These threads always go round in circles seemingly forever. To summarise:

1. Generally 8 bitters are simpler and easier to code at a low level
2. You can always use a 32-bit part in place of an 8-bit, unless you are very high volume and really need to save every cent on unit cost
3. In a lot of cases 8-bitters just don't have the power so a 16 or 32 bit is needed
Bob
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Online Kjelt

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Re: 8-bit uC - is there even a point?
« Reply #104 on: September 28, 2018, 07:37:57 pm »
$70 cents on 1000 units is $700 dollars. On average little over 1 days worth of engineering time. One of the things I've learned over the years is to start looking at component costs at much higher volumes than 1000 units. However it is good to put a lot of thought into production. Again looking at component costs only can severely hurt your business if a product take too long to program & test.
70 cents here and there. I don't think one will limit not caring about expenses to MCU only, in the end will end up up with 3-5 times more expensive BOM.
You are making the same mistake as many others: you don't care about engineering time!
I know saving a few cents from the BOM gets you an 'atta boy' quickly because it is easy to visualise. However in many projects simple costs savings end up to become huge time sinks. If you need to spend a few weeks to try and optimise code because of a silicon bug, too litle memory or lesser performance in a cheaper microcontroller you'll end up losing your bosses' money. And it is not just development time but also the sales start later. Not to mention the time could have been spend on the next product.
Indeed socalled NRE costs can be huge. The problem is that the target for some manager is BOM reduction and not overall cost reduction. A lot of managers also take on a project just to keep their personell busy so their budget and fte's are not cut next budget round. Last don't forget ignorance, how much effort will it eventually be to change from lets say a PIC16 to an ST32F0 , most have absolutely no clue.
 

Offline rx8pilot

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Re: 8-bit uC - is there even a point?
« Reply #105 on: September 28, 2018, 08:11:09 pm »
Indeed socalled NRE costs can be huge. The problem is that the target for some manager is BOM reduction and not overall cost reduction. A lot of managers also take on a project just to keep their personell busy so their budget and fte's are not cut next budget round. Last don't forget ignorance, how much effort will it eventually be to change from lets say a PIC16 to an ST32F0 , most have absolutely no clue.

For sure - I have all sorts of functionality coded, documented, and proven solid on 8bit AVR's. My last and current projects may have benefited from more powerful chips - but it would have delayed the release by months. Opportunity costs and development costs explode and I am back to a Ramen noodle diet for 6 months. Introducing a new architecture will certainly have a time penalty. Hell, I am using a single micro to generate a 3 phase clock to sync power converters. Super easy and I have control via I2C after assembly. Cheap, easy, and the success is nearly guaranteed. I have the chips in stock and loaded into the pick_and_place because they are used in a dozen other projects for totally different tasks. I use the same chip to monitor a soft power switch and drive 2 RGB LED's, communicating over 2-wire I2C. It is easy.

For the most part - I generally prioritize speed and predictability during design. I need to do some low-priority projects with some fancier uC's to develop the skills and libraries without the time/financial pressure.
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Offline NorthGuy

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Re: 8-bit uC - is there even a point?
« Reply #106 on: September 28, 2018, 08:35:26 pm »
... you don't care about engineering time!

Engineering time also depends on who's doing the job. You'll work much faster and better if you work with something you're already familiar with. From the boss' point of view - if I employed nctnico, I would make sure to give him ARM based jobs. On the other hand, Siwastaja would have zero chance of getting ARM job - all the ARM jobs would go to nctnico!

 :-DD
 

Offline nctnico

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Re: 8-bit uC - is there even a point?
« Reply #107 on: September 28, 2018, 09:40:52 pm »
Indeed socalled NRE costs can be huge. The problem is that the target for some manager is BOM reduction and not overall cost reduction. A lot of managers also take on a project just to keep their personell busy so their budget and fte's are not cut next budget round. Last don't forget ignorance, how much effort will it eventually be to change from lets say a PIC16 to an ST32F0 , most have absolutely no clue.
For sure - I have all sorts of functionality coded, documented, and proven solid on 8bit AVR's. My last and current projects may have benefited from more powerful chips - but it would have delayed the release by months. Opportunity costs and development costs explode and I am back to a Ramen noodle diet for 6 months. Introducing a new architecture will certainly have a time penalty. Hell, I am using a single micro to generate a 3 phase clock to sync power converters. Super easy and I have control via I2C after assembly. Cheap, easy, and the success is nearly guaranteed. I have the chips in stock and loaded into the pick_and_place because they are used in a dozen other projects for totally different tasks. I use the same chip to monitor a soft power switch and drive 2 RGB LED's, communicating over 2-wire I2C. It is easy.

For the most part - I generally prioritize speed and predictability during design. I need to do some low-priority projects with some fancier uC's to develop the skills and libraries without the time/financial pressure.
That is another problem of going for 8 bitters: they run out of steam at some point and then you have to go up the learning curve again.

-sales pitch mode- I've been messing with microcontrollers for decades and have used many different types. When the ARM based controllers started to get mainstream (not the Cortex Mx ones but the ones with the ARM7TDMI CPU) I evaluated a whole bunch of them carefully and decided to go with the LPC series from NXP. These have a serial bootloader and you can program these using a free tool (and TTL level serial port signals). This has proven to be a good choice because whether it is a 14 pin deviced or 214 pin device: I can use the same low level hardware drivers and the transition fromt ARM7TDMI core to Cortex Mx core was easy as well because NXP kept using the same peripherals. As a result nearly every project I do has a different microcontroller in it (which fits the project). I'm not stuck to a limited choice of microcontrollers.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Online Kjelt

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Re: 8-bit uC - is there even a point?
« Reply #108 on: September 28, 2018, 09:54:53 pm »
As a result nearly every project I do has a different microcontroller in it (which fits the project). I'm not stuck to a limited choice of microcontrollers.
Yes you are since you limit yourself to NXP  :-*
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Online FrankBuss

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Re: 8-bit uC - is there even a point?
« Reply #109 on: September 29, 2018, 12:57:32 am »
I'm sure you can run it bare-metal as well.

I'd assume you can run a barebones binary from uboot

Right, this would be the easiest way. Boot time would be much less than a second as well, and you could integrate your program in u-boot itself, which then autostarts after u-boot did all the hard stuff like setting up the PLL etc. Don't know the version on the Allwinner, but usually u-boot even supports USB and network.
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Online FrankBuss

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Re: 8-bit uC - is there even a point?
« Reply #110 on: September 29, 2018, 01:01:00 am »
There are many applications where it needs to be faster and where you need more memory, for example for video IO (this chip has an ethernet interface and a camera input, so probably could be used as a web cam), or polyphonic realtime audio synthesis with effects (reverb needs lots of memory). And the Allwinner V3s is not just a core, it has some useful peripherals as well, see the datasheet, like DMA, PWM, SPI, I2C, UART, audio codec etc. So if you don't miss a peripheral for your application, it could be a cheap replacement for the higher priced STM32 series chips, but with more RAM and much faster. It can run slower as well, probably using not much more power then as a STM32 running at 180 MHz.

This is not the sort of thing that microcontrollers are typically used for. Do you really want to wait for Linux to boot and think about crashes, memory leaks, hacks, etc in your microwave oven, dishwasher, clothes washer and dryer, tv remote, alarm clock, etc? Linux SOCs and microcontrollers are two entirely different fields with some small bit of overlap in the middle. The strength of the microcontroller is in the peripherals, and the simplicity. There is effectively no boot time, there is no operating system, everything happens in real time and can be tweaked down to individual clock cycles. You can get microcontrollers in tiny packages with only a few pins, you can get ones that consume miniscule amounts of power. It is absolutely silly to suggest a Linux SOC for microcontroller applications, even if the Linux route was cheaper the end result would be inferior for the sort of applications where microcontrollers are typically used.

I agree that it doesn't make sense to use Linux for a remote control. I was suggesting it as a replacement for the high end microcontrollers. Don't know about e.g. a clothes washer, it could monitor the clothes with a cam, then send it over ethernet :) Just the network stack etc. would be a hassle without an operating system on one of the conventional high end microcontrollers. On a Linux IC you could write the whole thing with a few lines of Python code.
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Online Kjelt

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Re: 8-bit uC - is there even a point?
« Reply #111 on: September 29, 2018, 08:38:32 am »
I agree that a small Linux platform is an easy IoT starter but it is also an easy target for hackers as we have seen in the multiple compromised IP cameras , videorecorders and other IoT devices on the IoT wall of shame. So the biggest issue you face are:

1) hardening your product, shutting down each and every unused port/service etc that could pose a threat, security penetration testing by a professional organisation to check if you got it right

2)after release : security lifecycle management/maintenance of your product, having to keep track of all published vulnerabilities and update the device accordingly.

With a simple arm cortex you face less risk since you dont have the large ram, the ip stack is so limited a hacker has little options to exploit it or use it as an attack platform for the rest of the network (There are no services not even a filesystem in most cases).
So if you look at the list of exploited embedded devices they score way better than the standardized linux platforms which is not a surprise.
 
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Offline Siwastaja

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Re: 8-bit uC - is there even a point?
« Reply #112 on: September 29, 2018, 08:46:17 am »
Engineering time also depends on who's doing the job. You'll work much faster and better if you work with something you're already familiar with. From the boss' point of view - if I employed nctnico, I would make sure to give him ARM based jobs. On the other hand, Siwastaja would have zero chance of getting ARM job - all the ARM jobs would go to nctnico!

What the heck is an "ARM job"? If this is about designing ARM processors or MCUs/SOCs using ARM cores, I understand this.  For a PCB/software design work that only utilizes "ARM things" as components - nope, you want a broader perspective. The core is just a single detail. Complete MCU architecture (peripherals!!) is more meaningful - and how you use it. Experience on many different product families (and preferably several manufacturers - still my weakest point, I mostly know about AVR, STM32 and Altera FPGAs) really helps here. OTOH, you can't be deeply experienced in too many different things. It's a trade-off.

This is exactly why I love to work in a fairly small startup, where I can be in the "CTO" role as well, and be employed by my own company. In-depth knowledge and ability to bring results matter, and we have basically no cargo cult on technical matters, which is absolutely great. Small engineering team of about four people is easy to work with, and everybody trusts me 100% on matters regarding electronics and low-level software. I can choose who I play with, and I have a lot to say to who gets hired. So, simply put, I don't need to be hired by people like you, and I don't need to play your office games.

I rather take the business uncertainty and risks of a small startup.

The perspective-less belief in "getting things done quickly" by using trend tools - typically chosen with Powerpoints, by people who are not actually writing the code - and reusing other's code as much as possible works on a small timescale.

This is the inevitable way to work when the engineers don't have the skills to do it otherwise, and it always seems like the right choice - short term. It also works on larger corporations with established tradition to bring out mediocre mass products where large engineering costs (by using ineffective design practices and teams too large) do not matter.

Long term, and when you want to develop something really ground-breaking (not just a new coffee maker), it's well worth investing some years of time so that the engineers learn. For me, it happened during two decades of  "hobby / enterpreneur hybrid", and thanks to me being able to insist on not listening those who tell me how I "should" be doing things. According to masses, I have always been "wrong". Funnily, during that time, the way things "should" be done changed so many times that you never learn any of those ways properly, anyway. Also, no one remembers those "right ways" of doing things after a decade.

Suddenly, I was able to start saying "yes" for complex work on projects involving other people. And suddenly, I could say "yes" on taking the leading role.

Gain experience on real projects, always do it your own way. Believe in your skills and your intuition, even if it goes wrong sometimes - that way you learn, and after a decade of doing it like this, you suddenly realize you are not going too wrong anymore, and can make fairly good estimates of the project timeline, cost, and communicate with others, using their terms as well - while still doing it your way.

Don't be arrogant.

Would I hire you or nctnico? I don't know. I don't see too many problems in your or nctnico's posts, and see a lot of good points, most of which I totally agree with. But this kind of forum babble doesn't give enough information about how you would really succeed in a complex, real world project, with real-world constraints.

Also, I trust that a real team doesn't need to agree on everything; but instead of arguing, or even worse, compromising trying to find the "middle road", they should be all doing things in a way which they are most productive; summing their (different) skills.
« Last Edit: September 29, 2018, 08:57:53 am by Siwastaja »
 

Offline nctnico

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Re: 8-bit uC - is there even a point?
« Reply #113 on: September 29, 2018, 09:16:18 am »
I'm sure you can run it bare-metal as well.

I'd assume you can run a barebones binary from uboot

Right, this would be the easiest way. Boot time would be much less than a second as well, and you could integrate your program in u-boot itself, which then autostarts after u-boot did all the hard stuff like setting up the PLL etc. Don't know the version on the Allwinner, but usually u-boot even supports USB and network.
True. Some of the bootloaders (u-boot isn't the only one) have turned into mini-OSses with a lot of functionality. So if you need a lot of processing power / memory in a microcontroller-ish application I would see this method as an option.
« Last Edit: September 29, 2018, 09:26:44 am by nctnico »
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Online GeorgeOfTheJungle

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Re: 8-bit uC - is there even a point?
« Reply #114 on: September 29, 2018, 09:20:28 am »
As a hobbyst, is there still a point in using them or should I invest my time in learning ARM platform?

Absolutely, don't waste your time with 8 bitters, ARM is the way to go.

http://infocenter.arm.com/help/index.jsp







Also in arduino form:


« Last Edit: October 03, 2018, 07:24:36 am by GeorgeOfTheJungle »
git diff *
 

Offline Mr. Scram

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Re: 8-bit uC - is there even a point?
« Reply #115 on: September 29, 2018, 02:37:07 pm »
Absolutely, don't waste your time with 8 bitters, ARM is the way to go.

http://infocenter.arm.com/help/index.jsp







Also in arduino form:


With zero arguments you're not exactly making a strong case, especially considering there's a thread's worth of arguments why 8 bit chips are relevant.
 
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Online GeorgeOfTheJungle

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Re: 8-bit uC - is there even a point?
« Reply #116 on: September 29, 2018, 06:32:11 pm »
With zero arguments you're not exactly making a strong case, especially considering there's a thread's worth of arguments why 8 bit chips are relevant.

The OP: "[...] I'm trying to select a (µC) chip to learn [...]".

Had he said "I'm trying to learn electronics", you'd recommend to begin with thermionic valves? No.

There's a reason the entire world has moved on to ARM µCs already, big time, to the tune of billions of µCs per year. And you want to steer him into a dead end road?

Eight bitters are obsolete, a thing of the past, "not recommended for new designs".

Both Apple and Microsoft are working to migrate their products from Intel to ARM-based processors developed in-house.
« Last Edit: September 29, 2018, 07:46:46 pm by GeorgeOfTheJungle »
git diff *
 

Online wraper

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Re: 8-bit uC - is there even a point?
« Reply #117 on: September 29, 2018, 06:49:57 pm »
There's a reason the entire world has moved on to ARM µCs already, big time, to the tune of billions of µCs per year. And you want to steer him into a dead end road?

Eight bitters are obsolete, a thing of the past, "not recommended for new designs".
Really, entire world? Then why new parts still appear no the market?

Quote
Semiconductor MCU revenue market forecast –millions of dollars
 

Offline rx8pilot

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Re: 8-bit uC - is there even a point?
« Reply #118 on: September 29, 2018, 06:51:46 pm »
The OP: "[..] I'm trying to select a (µC) chip to learn [..]".

Had he said "I'm trying to learn electronics", you'd recommend to begin with thermionic valves? No.

There's a reason the entire world has moved on to ARM µCs already, big time, to the tune of billions of µCs per year. And you want to steer him into a dead end road?

Eight bitters are obsolete, a thing of the past, "not recommended for new designs".

8bit is a great place to learn the basics. They provide a solid baseline skill set that translates to all sorts of more complex architectures. They also provide a CRITICAL understanding of system efficiency. When a developer or programmer is using completely overkill hardware - it promotes sloppy and inefficient programming/development techniques.

Sloppy design and coding require more physical resources, more parts, more RAM, more pins, more costs, etc. In the use case of learning - the limitation of 8 bit is not a limitation. They provide a problem big enough to learn, but small enough to tackle. They also force the student to pay attention to the details when they are pushing the limits of the part.
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Online GeorgeOfTheJungle

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Re: 8-bit uC - is there even a point?
« Reply #119 on: September 29, 2018, 07:26:50 pm »
8bit is a great place to learn the basics. They provide a solid baseline skill set that translates to all sorts of more complex architectures.

There are simple ARM µCs too, and ARM assembly is easy peasy, a much better design and much easier to understand than the arbitrary ISA messes of the obsolete 8 bitters.
git diff *
 

Offline nctnico

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Re: 8-bit uC - is there even a point?
« Reply #120 on: September 29, 2018, 08:12:08 pm »
Eight bitters are obsolete, a thing of the past, "not recommended for new designs".
8bit is a great place to learn the basics. They provide a solid baseline skill set that translates to all sorts of more complex architectures. They also provide a CRITICAL understanding of system efficiency. When a developer or programmer is using completely overkill hardware - it promotes sloppy and inefficient programming/development techniques.
IMHO this is wrong. There is absolutely no reason you can't learn to program efficiently on an ARM. Just give a student an assignment for which the C compiler can't do it's optimising magic. If necessary the knowledge can be applied to 8 bit as well but in today's situation not learning ARM means someone is behind. And anyone who is claiming ARM is more complicated than 8 bit clearly has never really looked at a simple ARM controller. These do exist and are easier to understand compared to a 8051.
« Last Edit: September 29, 2018, 08:15:04 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Online Kjelt

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Re: 8-bit uC - is there even a point?
« Reply #121 on: September 29, 2018, 08:31:02 pm »
but in today's situation not learning ARM means someone is behind. And anyone who is claiming ARM is more complicated than 8 bit clearly has never really looked at a simple ARM controller. These do exist and are easier to understand compared to a 8051.
You lost me here.
OR you learn the ARM core and read the thousands of pages, study registers and opcodes/assembly instructions   It sure is more complicated than 8 bit cores.
But almost no-one using Arms does that, hell almost no-one using 8 bitters look at the core, how many registers it has, hardware or sw multiplier etc, they just code C and let the compiler figure it out.
So probably you mean the other features the ARM core has such as DMA , clocks etc.

If you mean the peripherals that has 0 to do with ARM but I know you know that so that is not what you meant, so what exactly did you mean to say ?
 

Offline rx8pilot

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Re: 8-bit uC - is there even a point?
« Reply #122 on: September 29, 2018, 08:35:06 pm »
IMHO this is wrong. There is absolutely no reason you can't learn to program efficiently on an ARM.

Fair enough.....
People learning application programming on 64bit systems with massive RAM and Storage resources have absolutely no reason they cannot learn efficient programming either, yet many do not.
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Offline nctnico

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Re: 8-bit uC - is there even a point?
« Reply #123 on: September 29, 2018, 08:48:20 pm »
but in today's situation not learning ARM means someone is behind. And anyone who is claiming ARM is more complicated than 8 bit clearly has never really looked at a simple ARM controller. These do exist and are easier to understand compared to a 8051.
You lost me here.
OR you learn the ARM core and read the thousands of pages, study registers and opcodes/assembly instructions   It sure is more complicated than 8 bit cores.

If you mean the peripherals that has 0 to do with ARM but I know you know that so that is not what you meant, so what exactly did you mean to say ?
Just take a low end ARM controller from NXP like the LPC1111 as an example. These don't have many fancy features and don't need a single line of assembly to get going. Also you don't need to study thousands of pages about the ARM core. Where did you get that idea from? System integrators who design microcontrollers and SoCs may want to know all the ins&outs but I for sure don't need to know all that. If you want to program using assembly then all the opcodes for the ARM fit on two (or three) pages. Even better: it has less addressing modes and memory areas compared to the 8051 so less to worry about.

AFAIK the only thing I ever looked up in the ARM Cortex manual is the order in which the registers are saved onto the stack before an interrupt so I can print a stack trace in case of a memory fault.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online Kjelt

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Re: 8-bit uC - is there even a point?
« Reply #124 on: September 29, 2018, 08:58:31 pm »
I agree but if you look at it from that perspective there is not that much difference programming C between Arm or STM8 for instance, you just code C. So why would someone be behind? If you learn Arm you learn the core how many registers etc. You could argue the high speed busses, i would agree.

If you need  writing some part of the code in assembly because for instance you need the speed of a multiply with carry that C does not support, you need to know how many registers there are where they are used for and where you can safely put your results. In that sense an Arm is hugely different many more registers from an Stm8.
 


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