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by tufty
Fri Jun 19, 2015 9:02 am
Forum: Bare metal, Assembly language
Topic: Dedicating one core to hard realtime tasks
Replies: 26
Views: 9809

Re: Dedicating one core to hard realtime tasks

Yep, I understood that. The software in Octopi could be a start for him! And yet you missed that the OP had actually mentioned Octoprint in the original post. Now, AIUI, the PRUs in the beaglebone black are entirely decoupled, hard-realtime subsystems. The cores on the Pi2, even if you manage to is...
by tufty
Sun Jun 07, 2015 1:42 pm
Forum: Bare metal, Assembly language
Topic: RTOS - which? status?
Replies: 6
Views: 3075

Re: RTOS - which? status?

kriss wrote:the nice bear rsp user do uspi from where you can start ;)

Code: Select all

?SYNTAX ERROR

FORMULA TOO COMPLEX
by tufty
Tue May 26, 2015 5:52 am
Forum: Bare metal, Assembly language
Topic: turning on SCU on RPI2
Replies: 10
Views: 1773

Re: turning on SCU on RPI2

JS2 wrote:I can't find a good terminal that allows copy/paste
If you have access to a *n*x machine or VM, use screen. On Windows, PuTTY should be able to do what you want.
by tufty
Thu May 21, 2015 6:36 pm
Forum: Bare metal, Assembly language
Topic: Linker script nightmare -- please help!
Replies: 3
Views: 718

Re: Linker script nightmare -- please help!

Is BT_LINKER_INIT_SECTION being defined somewhere?
by tufty
Wed Apr 15, 2015 5:31 pm
Forum: Bare metal, Assembly language
Topic: Want to implement backspace function in USPi library
Replies: 4
Views: 718

Re: Want to implement backspace function in USPi library

rst wrote:Please note that this sample is not intended to provide a full functioning line or screen editor. You have to implement it on your own if you need one.
http://www.finseth.com/craft/
by tufty
Fri Apr 10, 2015 6:39 pm
Forum: Bare metal, Assembly language
Topic: DSB instruction and ARMv6
Replies: 3
Views: 2373

Re: DSB instruction and ARMv6

by tufty
Thu Apr 02, 2015 9:24 am
Forum: Bare metal, Assembly language
Topic: Good asm-learning books?
Replies: 22
Views: 2458

Re: Good asm-learning books?

Mine's DDI 0406A "Arm Architecture Reference Manual ARM®v7-A and ARM®v7-R edition"

Your DDI 0406C is simply a later revision, so page numbers may not exactly match.
by tufty
Thu Apr 02, 2015 6:11 am
Forum: Bare metal, Assembly language
Topic: Good asm-learning books?
Replies: 22
Views: 2458

Re: Good asm-learning books?

but the programmer needs to be aware of what range of values is allowable for certain commands. Thanks. The ARMv7AR-ARM (which covers the instruction sets used by both Pi models) describes all the encodings, by opcode, with any extra restrictions on availability. So, for example, the MOVW / MOVT pa...
by tufty
Wed Apr 01, 2015 6:14 pm
Forum: Bare metal, Assembly language
Topic: Good asm-learning books?
Replies: 22
Views: 2458

Re: Good asm-learning books?

To visualise what's do-able with 12 bit immediates, you must understand that the set (or unset, in the case of complemented values) bits in the required value must all be at least in one contiguous 8 bit span. In other words, it must be possible to rotate the value to give a value <= 0xff With that ...
by tufty
Wed Apr 01, 2015 5:57 pm
Forum: Bare metal, Assembly language
Topic: Good asm-learning books?
Replies: 22
Views: 2458

Re: Good asm-learning books?

There is auto-increment. ;; Load Rt with the contents of memory pointed to by Rn (plus or minus 12 bit value imm), update Rn LDR<c> <Rt>,[<Rn>,#±<imm>]! ;; Load Rt with contents of memory pointed to by Rn, update Rt by adding / subtracting 12 bit value imm LDR<c> <Rt>, [<Rn], #±<imm> Those are the s...
by tufty
Mon Mar 30, 2015 4:07 pm
Forum: Bare metal, Assembly language
Topic: Which toolchain?
Replies: 19
Views: 6750

Re: Which toolchain?

That looks a lot like there are filename globbing issues going on there.
by tufty
Sun Mar 29, 2015 8:28 pm
Forum: Bare metal, Assembly language
Topic: Which toolchain?
Replies: 19
Views: 6750

Re: Which toolchain?

That's almost certainly a linker invocation error, it indicates that somehow startup.o is being linked twice into the finished executable. My guess would be that your linker script is to blame, that it's pulling the .text section from startup.o, and then *all* text sections. I generally use a separa...
by tufty
Sun Mar 29, 2015 10:49 am
Forum: Bare metal, Assembly language
Topic: Which toolchain?
Replies: 19
Views: 6750

Re: Which toolchain?

Compiling your own toolchain is pretty much a minority interest. You should be able to get by with an off-the-shelf toolchain (the CPUs on the pi models are not exactly bleeding edge) unless you're looking for a specific optimisation that's only available in a specific version of a compiler, testing...
by tufty
Sat Mar 21, 2015 7:46 am
Forum: Bare metal, Assembly language
Topic: USB on RPi
Replies: 12
Views: 1889

Re: USB on RPi

A-ha. Also the ethernet is behind the USB. Isn't it a bit heavy for the USB? What kind of USB-device the ethernet is? CDC - probably, but what subtype? I understood that it's programmed into the EEPROM, so the chip manufacturer can't possibly know. IIRC it shows up as a hub boot log extract from th...
by tufty
Mon Mar 16, 2015 1:31 pm
Forum: Bare metal, Assembly language
Topic: USB on RPi
Replies: 12
Views: 1889

Re: USB on RPi

Also, I wonder if the specs of, say, STM32F407 (the high speed OTG) fits the BCM2835/2836 USB controller? At least it says in the STM-specs (chap 35 USB on-the-go high-speed (OTG_HS), page 1363) http://www.st.com/web/en/resource/technical/document/reference_manual/DM00031020.pdf Portions Copyright ...
by tufty
Sun Mar 15, 2015 7:42 pm
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

jamesh wrote:the more idiosyncratic parts of the SoC.
...such as the USB or the MMC parts. Idiosyncratic indeed.

Yes, I *do* understand that the documentation for the USB and MMC IP is not Broadcom's, let alone the Foundation's, and that it can't be simply splashed about willy-nilly.
by tufty
Wed Mar 11, 2015 5:14 pm
Forum: Bare metal, Assembly language
Topic: 4 7 segment LED display
Replies: 5
Views: 1354

Re: 4 7 segment LED display

It ain't gonna happen, no matter what you read in these forums. If it were possible, you could easily buy an Assembler for the RPi's ARM chip You can. There are a number of very good commercial ARM assemblers which target both the original Pi's 1176jzf-s and the Pi 2's Cortex-A7. Suppliers who spri...
by tufty
Mon Mar 09, 2015 7:35 pm
Forum: General programming discussion
Topic: Changing color scheme within emacs?
Replies: 1
Views: 577

Re: Changing color scheme within emacs?

If you're using a recent emacs, it should have package management built in. M-x package-list-packages (use the autocomplete, so actually M-x pac<tab>l<tab>) lists the packages you have available (needs a network connection) and then search through the list for 'theme'. Install and enable (M-x custom...
by tufty
Mon Mar 09, 2015 5:32 pm
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

If you want some further reading, you might want to look into the LuaJIT, Spidermonkey, and Tracemonkey compilers. There's a bunch of good stuff on lambda-the-ultimate, too
by tufty
Sun Mar 08, 2015 9:24 pm
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

I heard the claim that Java is as fast or faster than C and yet I cannot understand how that is possible. Given C's reputation as a high level 'assembler', and the considerable amount of work that has been done on optimisations, how can Java be faster? I can see where similar code MIGHT be able to ...
by tufty
Sat Mar 07, 2015 8:17 am
Forum: Bare metal, Assembly language
Topic: which simple, close to metal OS, has fast write to SDcard ?
Replies: 29
Views: 3896

Re: which simple, close to metal OS, has fast write to SDcar

I'm no expert on the Pi's GPIO, but I strongly suspect that the Pi isn't the tool you need here. Linux will almost certainly be getting in the way, which means bare metal (or nearly so) access, and even then I think you're probably going to be fighting the architecture. For what you're wanting, you ...
by tufty
Fri Mar 06, 2015 7:40 pm
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

I guess I am coming from a C/C++ direction. I doubt Eclipse will work particularly well (It does run, but I never spent any time past the splash screen, and being Java means there is yet another level of CPU redirection), but I am sure there are some IDE's out there that will be OK! Java is a byte-...
by tufty
Sun Mar 01, 2015 2:46 pm
Forum: Bare metal, Assembly language
Topic: Bare metal for real time sound?
Replies: 9
Views: 2813

Re: Bare metal for real time sound?

Yeah, "soft real time" should be more than good enough for most sound usages. You might want to try Sonic Pi, which does "real time" livecoded music / sound synthesis in ruby.
by tufty
Sun Mar 01, 2015 8:31 am
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

The Allwinner chips secret cause is that they are basic designs with mostly bought in ARM RTL, Arm cores, Mali, erc. They are thrown together quickly, not particularly cleverly, but they work and they are cheap. Support is fairly low end, you get what you pay for. As opposed to Broadcom, where, arg...
by tufty
Sat Feb 21, 2015 8:27 pm
Forum: Bare metal, Assembly language
Topic: BCM 2836 and the RPi 2 ?
Replies: 95
Views: 26971

Re: BCM 2836 and the RPi 2 ?

It is pretty simple! Those of you that think that everything needs to be open source, make a product! Give out 100% details on it. You will make the first 1000 units, maybe, then someplace in Asia will make the next million or so for you. And they will probably just happen to forget to share any pr...

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