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by stevendodd
Fri May 10, 2013 5:47 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Drive MAX7219 with I2C with shell script
Replies: 31
Views: 10490

Re: Drive MAX7219 with I2C with shell script

I know this is an old post but as these are quite cheap on ebay http://www.ebay.co.uk/sch/i.html?_nkw=max7219+Arduino I thought someone might like some working python code to get started as it took some effort to get all this together. Rather than using GPI I managed to get it going with the Raspber...
by stevendodd
Mon Sep 24, 2012 8:52 pm
Forum: Bare metal, Assembly language
Topic: Beginning with Bare Metal
Replies: 52
Views: 19631

Re: Beginning with Bare Metal

I started on a baremetal tutorial. https://github.com/dwelch67/raspberrypi ... /baremetal Long winded as usual (still a first and very rough draft), hopefully though it helps folks with a foundation for using the gnu tools. The two major issues I see with learning bare metal programming for the fir...
by stevendodd
Sun Sep 23, 2012 8:16 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

For others just starting out with Baking PI - here is some more interesting and relevant information from another thread in this forum http://www.raspberrypi.org/phpBB3/viewt ... 72&t=15387
by stevendodd
Sun Sep 23, 2012 7:03 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

I can only guess the GetGpioAddress is absolute because its part of the firmware.... /*------------------------------------------------------------------------------ * Return the physical address of the GPIO region into r0. ----------------------------------------------------------------------------...
by stevendodd
Sun Sep 23, 2012 6:52 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

Been reading a lot today; To be honest - I have still not got a sufficient understanding of what is going on. I think my main problem is that I do not yet have a broad enough knowledge base in this area and so I am content for now to put the solution you put forward Simon and a similar one here from...
by stevendodd
Fri Sep 21, 2012 1:25 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

thanks for the responses guys - i will absorb them and be back soon
by stevendodd
Fri Sep 21, 2012 8:12 am
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

I only have time to answer one of those questions at the moment as it's my wife's birthday and I will otherwise be in the dog box... Does the sample ld script I posted above work for both versions of the firmware? No it does not - if I have kernel_old=1 in config.txt with the .init section address s...
by stevendodd
Fri Sep 21, 2012 8:02 am
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

I should add...

As far as I can tell the only code at 0x0000 in this kernel is a .globl _start declaration and branch to the .main section supposedly at 0x8000 according to the ld script.
by stevendodd
Fri Sep 21, 2012 7:55 am
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

Thanks Simon - I suspected I didn't want to know the answer now I know. Loads more questions for me to knock about with. Your answer is very helpful in clearing up what is going on and for highlighting a solid solution going forward even though I don't fully understand it yet. :D Focusing narrowly o...
by stevendodd
Thu Sep 20, 2012 9:09 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

Here is some bed time reading regarding linker scripts http://www.gnuarm.com/pdf/ld.pdf Chapters 3.1 -> 3.3 provide the answers about the SECTIONS format But in answer to my 2nd question Do I need to move the init section from 0x0000 The answer is yes the code no longer worked unless I started the i...
by stevendodd
Thu Sep 20, 2012 8:01 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

Thanks for the response DexOS - I took a very quick look at your projects and will definitely go back for another look when I find more time, they look like fun. First of all your suggested code change worked, I made the change and then reverted the config.txt file back to the default, so thank-you ...
by stevendodd
Thu Sep 20, 2012 4:53 pm
Forum: Bare metal, Assembly language
Topic: Baking Pi
Replies: 168
Views: 31250

Re: Baking Pi

You could just change the start offset to 0x8000 etc and it will run fine. What do you mean by this please, I am having the same issue and I would like to understand why the tutorial is now broken. From what I can tell the author of the course already does start at that address? Also this is the sa...
by stevendodd
Sun Jun 10, 2012 3:15 pm
Forum: General discussion
Topic: Simulator & emulator downloads
Replies: 25
Views: 31988

Re: Simulator & emulator downloads

Thanks for the image - just a quick note for others if you copy the VMWare image you need to remove the MAC address cache:

Code: Select all

sudo rm /etc/udev/rules.d/70-persistent-net.rules
More info here:
http://www.orzeszek.org/blog/2010/07/25 ... -machines/
by stevendodd
Sun Jun 10, 2012 3:14 pm
Forum: General discussion
Topic: Simulator & emulator downloads
Replies: 25
Views: 31988

Re: Simulator & emulator downloads

Thanks for the image - just a quick note for others if you copy the VMWare image you need to remove the MAC address cache:

Code: Select all

sudo rm /etc/udev/rules.d/70-persistent-net.rules
More info here:
http://www.orzeszek.org/blog/2010/07/25 ... -machines/

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