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by williamssimonp
Sun Aug 18, 2013 10:19 am
Forum: Bare metal, Assembly language
Topic: GPIO access help needed.
Replies: 2
Views: 952

Re: GPIO access help needed.

And immediately switches off the UART, freezing the console! Like I said, something stupid! I have amended the code to gpio_registers[GPIO_GPFSEL0 + (minor / 10)] &= ~(7 << ((minor % 10) * 3)); gpio_registers[GPIO_GPFSEL0 + (minor / 10)] |= (GPIO_MODE_OUTPUT << ((minor % 10) * 3)); and it is working...
by williamssimonp
Sat Aug 17, 2013 11:08 pm
Forum: Bare metal, Assembly language
Topic: GPIO access help needed.
Replies: 2
Views: 952

GPIO access help needed.

I am currently trying to write an RTEMS application for the Pi. One of the first things I need is a driver for GPIO. I am fairly new to ARM and very new to RTEMS! I got the driver to the point where it was doing everything that it should, except that it wasn't actually accessing the GPIO registers, ...
by williamssimonp
Sun Mar 10, 2013 12:29 am
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Re: Model A board problem

Incidentally, I wouldn't have had the problem if I had used the supplied Makefile as it specifies:

Code: Select all

$(ARMGNU)-ld vectors.o armjtag.o -T memmap -o armjtag.elf
whereas my Eclipse generated Makefile lists the object files in alphabetical order.
by williamssimonp
Sun Mar 10, 2013 12:03 am
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Re: Model A board problem

Got it. It was a stack issue. It was working on the Revision 2 by accident!!! I dissassembled the resulting code and discovered that armjtag.o was being linked at 0x8000 and not vectors.s, which meant that the stack pointer wasn't being initialised as it went straight into notmain. I changed the lin...
by williamssimonp
Sat Mar 09, 2013 10:57 pm
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Re: Model A board problem

I hope the pinout change is included in the Model A. It is not listed as a difference. The Model B board I have been working with is a Revision Two board. Out of interest, I just tried it on a Revision One board and got the same results that I get on the Model A. I don't understand how that can be a...
by williamssimonp
Sat Mar 09, 2013 11:49 am
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Re: Model A board problem

Oh there's nothing wrong with the files. They work fine to boot Fedora on both Model A and B. They also boot the JTAG enabler on the Model B board. It's something specific to the JTAG enabler by the look of it.
by williamssimonp
Sat Mar 09, 2013 10:46 am
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Re: Model A board problem

Thanks for the tip, but it still doesn't work.
by williamssimonp
Fri Mar 08, 2013 9:49 am
Forum: Bare metal, Assembly language
Topic: Model A board problem
Replies: 9
Views: 1962

Model A board problem

Hi guys, just a quicky. I have been successfully debugging my boot code on a spare Model B revision 2 for the last week using a JTAGKey-Tiny, OpenOCD and Eclipse. I am using the code from https://github.com/dwelch67/raspberrypi/tree/master/armjtag to boot the Pi into 'JTAG Mode'. Once I had read the...
by williamssimonp
Mon Feb 11, 2013 10:36 pm
Forum: Bare metal, Assembly language
Topic: Windows 8, QEMU, MinGW and Eclipse.
Replies: 5
Views: 2322

Re: Windows 8, QEMU, MinGW and Eclipse.

This is what I want to do, when I get to that point, but how do I debug the debugger?! There is a UART based GDB server project on GitHub, I might use that initially, but it means you have to use the debugger software to load the the code to be tested. With this set up, how do you debug the initiali...
by williamssimonp
Mon Feb 11, 2013 4:04 pm
Forum: Bare metal, Assembly language
Topic: Windows 8, QEMU, MinGW and Eclipse.
Replies: 5
Views: 2322

Re: Windows 8, QEMU, MinGW and Eclipse.

If someone can tell me where to source a suitable JTAG cable at a reasonable price then I would love to use that. Once I have at least a decent screen driver working, then I can debug on the device, but until then I need to either emulate or use JTAG. JTAG would be my preferred solution if it weren'...
by williamssimonp
Mon Feb 11, 2013 1:10 pm
Forum: Bare metal, Assembly language
Topic: Windows 8, QEMU, MinGW and Eclipse.
Replies: 5
Views: 2322

Windows 8, QEMU, MinGW and Eclipse.

Hi Is anyone out there managing to use Torlus's Raspberry Pi branch on the QEMU code on Windows 8? I am using DevKitPro and Eclipse CDT to develop a bare metal system. Until I get to the point where I have booting and screen/keyboard stable, I want to use QEMU to debug under Eclipse. I have cloned a...
by williamssimonp
Tue Feb 05, 2013 9:36 am
Forum: C/C++
Topic: Extern "C" for assembler routine
Replies: 2
Views: 998

Re: Extern "C" for assembler routine

Just to so as not to give anyone incorrect information, my rusty C++ has shown itself. I was including the standard C libraries as we used to and, while that may still work, the correct way to do it is to include the new C++ libraries using: #include <cstdlib> or similar depending on the required li...
by williamssimonp
Mon Feb 04, 2013 7:17 pm
Forum: C/C++
Topic: Extern "C" for assembler routine
Replies: 2
Views: 998

Re: Extern "C" for assembler routine

Okay, I have no idea what was going on last night. I came home from work resigned to another evening of trying to track down the answer to this problem and it compiles fine exactly as it was, which is exactly how it is above. Sorry to have wasted everyone's time. One the other hand, if anyone needs ...
by williamssimonp
Mon Feb 04, 2013 1:52 pm
Forum: C/C++
Topic: Extern "C" for assembler routine
Replies: 2
Views: 998

Extern "C" for assembler routine

I am trying to call an assembler routine I have written from C++. The routine follows the EABI standard (assuming I understand it correctly). The routine takes three input parameters, which I believe will be delivered in r0, r1 and r2. These arguments are two integers and a pointer to a buffer which...
by williamssimonp
Tue Jan 29, 2013 1:21 pm
Forum: Bare metal, Assembly language
Topic: Structure of a bare metal program
Replies: 3
Views: 1459

Structure of a bare metal program

I'm new to ARM, despite being a developer with 25+ years experience. My first 5 years commercial experience was in assembler, Z80, 8086 and M68000 mainly. I am really enjoying getting back into this sort of coding and not having too many problems picking it up, but there is one thing that is confusi...
by williamssimonp
Wed Jan 23, 2013 10:57 am
Forum: Linux Kernel
Topic: Bare Linux kernel
Replies: 6
Views: 2313

Re: Bare Linux kernel

Arch Linux is plan B! If I do this, I will probably configure runlevel 2 to run just my control software and possibly runlevel 4 to run the control software with networking for debugging purposes. This would have the advantage that I could move to other runlevels if I wanted to mess about with the s...
by williamssimonp
Tue Jan 22, 2013 11:32 pm
Forum: Linux Kernel
Topic: Bare Linux kernel
Replies: 6
Views: 2313

Bare Linux kernel

Hi I am just starting out on a project involving using a Raspberry Pi to control an aerial photography platform. I don't like the idea of bare metal programming. I used to do that sort of thing years ago and it is very time consuming. I have been toying with the idea of booting a Linux kernel that t...
by williamssimonp
Fri Sep 14, 2012 8:28 am
Forum: Pidora / Fedora
Topic: Raspberry Pi Fedora Remix RC 1 & RC2
Replies: 25
Views: 11499

Re: Raspberry Pi Fedora Remix RC 1 & RC2

Well, I bit the bullet and hauled the Pi into the bedroom so I wouldn't disturb she who must be obeyed's TV watching and made two important discoveries, both good news. First, the Pi detected and used a wireless keyboard/mouse at first boot without batting an eyelid. Second, doing the first boot wit...
by williamssimonp
Thu Sep 13, 2012 12:53 pm
Forum: Pidora / Fedora
Topic: Raspberry Pi Fedora Remix RC 1 & RC2
Replies: 25
Views: 11499

Re: Raspberry Pi Fedora Remix RC 1 & RC2

I didn't have to use a monitor and keyboard to set up the Fedora 14 Remix and that was supposed to be the unstable one!!! I generally only use laptops at home. My servers all run headless (although I did have attach a keyboard and monitor to install CentOS in the first place, that was years ago!) an...
by williamssimonp
Wed Sep 12, 2012 8:07 am
Forum: Pidora / Fedora
Topic: Raspberry Pi Fedora Remix RC 1 & RC2
Replies: 25
Views: 11499

Re: Raspberry Pi Fedora Remix RC 1 & RC2

I've been attempting to boot RC2 on a headless Pi. The boot process appears to go okay as far as I can see, at least sshd is running, but it will not accept the root password. I had the Fedora 14 Remix running this way with no problem at all. It accepted the root password via SSH on first boot and t...

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