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by ga5941
Thu Jan 21, 2016 1:23 am
Forum: General discussion
Topic: R Pi 2 System clock
Replies: 3
Views: 751

Re: R Pi 2 System clock

There may be a way to set the UART speed on pins 8 & 10 described in "Raspberry Pi Users Guide, Third Edition" by Eben Upton and Gareth Halfacree, 2014. The exact wording used "You can set the speed in the cmdline.txt file - the speed is usually 115,200 bits per second". See also http://www.cs.unca....
by ga5941
Wed Jan 20, 2016 9:24 pm
Forum: General discussion
Topic: R Pi 2 System clock
Replies: 3
Views: 751

R Pi 2 System clock

Trying to program the Mini UART in the BCM2835 peripheral and I need to know the system clock frequency in order to load the Baud Rate register. In most micros this is one half the crystal frequency but I don't see any crystal on the Raspberry Pi 2 circuit board. Does anyone know what the frequency ...
by ga5941
Fri Apr 03, 2015 7:55 pm
Forum: Beginners
Topic: Where does RISC OS start execution on bootup?
Replies: 1
Views: 333

Where does RISC OS start execution on bootup?

I had assumed that RISC OS would start program execution from 0000 on bootup but on disassembling the code there I find nothing but junk way past 0x15000. My goal is to write my own simple OS to set up a bootloader. I want access to all the I/O without going through RISC or Raspbian OS. I have no ne...
by ga5941
Fri Apr 03, 2015 7:44 pm
Forum: Beginners
Topic: Connecting to GPIO while RasPi is powered on
Replies: 4
Views: 1684

Re: Connecting to GPIO while RasPi is powered on

I'm assuming you've read the BCM2835 datasheet that defines the registers. Otherwise start by Googling BCM2835. and download the datasheet. Now, there are different ways of accessing the GPIO pins, none of them simple. I can't begin to cover this topic adequately here; the best way is to get a book ...
by ga5941
Mon Mar 30, 2015 6:22 pm
Forum: Beginners
Topic: Floating Point Conversion from Strings
Replies: 3
Views: 890

Re: Floating Point Conversion from Strings

Thank you for your helpful consideration: I'll try to work through the code files.
by ga5941
Sun Mar 29, 2015 11:17 pm
Forum: Beginners
Topic: Floating Point Conversion from Strings
Replies: 3
Views: 890

Floating Point Conversion from Strings

My Raspberry Pi2 is running RISC OS and my programming is in assembly code. My problem is converting a keyboard input string representing a floating point number to a form that can be manipulated using VFP2 (floating point) commands. There must be a SWI call to do this similar to the strtod() functi...
by ga5941
Mon Mar 02, 2015 9:32 pm
Forum: Beginners
Topic: Keyboard layout changes
Replies: 2
Views: 357

Keyboard layout changes

Changing the keyboard layout via "sudo raspi-config" to accommodate the US style resulted in a surprise when the desktop environment was entered. The change would not take effect in the desktop environment until a reboot was executed. This is probably also true for other changes made in raspi-config...
by ga5941
Sun Mar 01, 2015 4:57 pm
Forum: Beginners
Topic: UART1 Baud rate calculation
Replies: 2
Views: 513

UART1 Baud rate calculation

Hi! My new RPi 2 was advertised as running at 900MHz and is this the system_clock_freq? Many FORUM posts mention 600MHz for RPi2 with actual clock frequency up to 900MHz dependent on actual CPU load. I need to set up UART1 to output a data stream to a serial LCD display at 9600 baud, RS232. The form...
by ga5941
Sat Feb 28, 2015 2:21 am
Forum: RISCOS
Topic: StrongED char size
Replies: 2
Views: 1585

Re: StrongED char size

Thanks for your solution to my font size problem. However, I found out another way before your response arrived in a book, "Teach Yourself Visually Raspberry Pi" by Richard Wentk. In a web browser I visited http://elinux.org/RPi_config.txt. For my TV I picked out hdmi_group=2 and resolution hdmi_mod...
by ga5941
Fri Feb 27, 2015 8:30 pm
Forum: Beginners
Topic: Multiple OSs
Replies: 8
Views: 1159

Multiple OSs

I've installed NOOBS v1.4.0 Raspbian - wheezy on one 8GB SD card for my my PI 2. On another 8GB card I've installed RISC-OS. It would be nice to have the option of selecting either Raspbian or RISC-OS at bootup without having to switch SD cards as I'm told the SD connections are not too robust and m...
by ga5941
Wed Feb 25, 2015 10:30 pm
Forum: RISCOS
Topic: StrongED char size
Replies: 2
Views: 1585

StrongED char size

Just downloaded the new RISC OS RC-14 and transfered the .img to my RPi 2. It boots up FAST! Still experimenting but having trouble reading the display in full size StrongED. Is there any way to increase the size of the characters short of displaying on a larger TV? Am now using a 20" HDTV.
by ga5941
Wed Feb 25, 2015 2:49 am
Forum: Beginners
Topic: RaspPi B+ as car computer
Replies: 8
Views: 1744

Re: RaspPi B+ as car computer

To sense ignition "ON" we must transform the voltage (12-14V) so it can be sensed by GPIO as a low condition (like connected to ground). Connect the +12V ignition source to the base of a 2N2222 transistor through a 7K resistor. Connect the emitter of the transistor to ground and the collector direct...
by ga5941
Mon Feb 23, 2015 11:24 pm
Forum: Beginners
Topic: RaspPi B+ as car computer
Replies: 8
Views: 1744

Re: RaspPi B+ as car computer

ga5941 12-14V will definitely fry your RPi. You need a 5V regulator like LM323. http://download.siliconexpert.com/pdfs/2013/3/20/22/21/59/296/st_/manual/9629cd00000466.pdf which will be happy with 14V (max 20V) and output 5 V @ 2 Amp. Spec sheet shows a typical application. I assume the computer is ...
by ga5941
Mon Feb 23, 2015 10:45 pm
Forum: Beginners
Topic: Freebasic install
Replies: 5
Views: 2355

Re: Freebasic install

Hi! Downloaded the file again and now its in ~/Downloads so in this directory I entered: sudo ./install.sh i /usr which returned: FreeBASIC compiler successfully installed in /usr Sounds like success but not quite! In desktop LXTerminal mode, the window opens in pi@raspberrypi /usr $ and when I ente...
by ga5941
Mon Feb 23, 2015 8:06 pm
Forum: Beginners
Topic: Freebasic install
Replies: 5
Views: 2355

Re: Freebasic install

Hi drgeoff! I downloaded on my Rpi2 the ARM7 debian version which is listed for Beaglebone Black (BBB): fbc-0.91.0-bbb-debian.tar.gz I can't find which directory it landed in. To first install Raspbian I entered; sudo apt-get update sudo apt-cache search Raspbian Search results included: linux-heade...
by ga5941
Sun Feb 22, 2015 7:45 pm
Forum: Beginners
Topic: Freebasic install
Replies: 5
Views: 2355

Freebasic install

I would like to program my RPi in BASIC which I understand will accept lines in assembler code. I downloaded to my PC from http://www.freebasic.net/forum/viewtopic.php?f=5&t=21433 this file for Raspberry Pi: fbc-0.91.0-pi-raspbian.tar.gz How to install this on my Raspberry Pi 2 which has NOOBSv1.4.0...
by ga5941
Sun Feb 22, 2015 6:57 pm
Forum: Beginners
Topic: GUI gvim text editor
Replies: 1
Views: 2068

GUI gvim text editor

I'm trying to install "gvim", the GUI version of text editor "vim". I entered: sudo apt-get install gvim and got messages back: Package gvim is a virtual package provided by: vim-gtk 2:7.3.547-7 vim-gnome 2:7.3.547-7 vim-athena 2:7.3.547-7 You should select one to install. I tried several ways to do...
by ga5941
Sat Feb 21, 2015 3:33 pm
Forum: Beginners
Topic: GCC Compiler for Assembly Language
Replies: 1
Views: 546

GCC Compiler for Assembly Language

Hi! My new Raspberry Pi 2 boots up OK and I selected the Raspbian OS from NOOBS v1.4.0 to install but I can't find the GCC Compiler and linker mentioned in Bruce Smith's book on Assembly Language for Raspbian Beginners. The Raspberry Pi website does not show any such listing nor does Smith's website...
by ga5941
Sun Feb 15, 2015 3:05 pm
Forum: General discussion
Topic: Documentation
Replies: 1
Views: 400

Documentation

Have not been able to find documentation relating to memory addresses for GPIO pins and the assembly commands to set pull-up/pull-down states. I have downloaded from ARM site the manual DEN0013D_cortex_a_series_PG which describes most assembly instructions but not the ones I need.

Can anyone help?
by ga5941
Thu Feb 12, 2015 2:53 pm
Forum: Beginners
Topic: SD card size
Replies: 2
Views: 483

SD card size

I'm a beginner and have not yet purchased an SD card for my new Raspberry Pi 2. Is there a maximum size it will tolerate? Looking forward to downloading other software, I'm thinking of a 32 GB San Disk Ultra (300 Mb/sec) available for only $24 at Walmart.

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