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by dwelch67
Fri Jun 08, 2012 7:25 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

Okay I get it now, it really wants you to start your program at 0x8000. Or lets say it wont load under that, wont load at 0x000 in arms space even with the config.txt setting (will accept addresses larger than that), perhaps because that is the gpu space and at least on boot it is using that space....
by dwelch67
Fri Jun 08, 2012 2:53 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I read up on the config.txt file, which if you are not running from a linux/mounted perspective is actually the root of the fat partition where kernel.img, etc lives. Change or create config.txt and arm_freq=200 to change the frequency, the default appears to be 700mhz if you dont have that file or...
by dwelch67
Fri Jun 08, 2012 1:54 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I read up on the config.txt file, which if you are not running from a linux/mounted perspective is actually the root of the fat partition where kernel.img, etc lives. Change or create config.txt and arm_freq=200 to change the frequency, the default appears to be 700mhz if you dont have that file or...
by dwelch67
Wed Jun 06, 2012 5:58 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

What I meant to say is, this was bare metal, something along the lines of test: subs r0,r0,#1 bne test and change the number of subs (to get a feel for the bne time), that kind of thing. No other code, no interrupts, no operating system. instruction cache on and off. I read up on the config.txt fil...
by dwelch67
Fri Jun 01, 2012 4:57 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I have the ARM JTAG up and running. Mostly on the P1 connector using jumper wires. One signal is from what I can tell not on P1. I did have to solder a wire on to S5 to get that signal. With a very simple boot program to switch the GPIO pins to their alternate functions you can use jtag to halt and ...
by dwelch67
Fri Jun 01, 2012 4:54 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

There is no JTAG on the Arm - you don't really need JTAG except during board bring up. You can write arm assembler and run it in the Linux environment using GDB as your debugger, which should be more than enough for learning Arm assembler, as should the documentation available - you don't need anyt...
by dwelch67
Fri Jun 01, 2012 4:52 am
Forum: General discussion
Topic: P2 connector use ?
Replies: 8
Views: 21208

Re: P2 connector use ?

Actually JTAG is a nice thing to have even for mere mortals, as long as it is used with caution and some commonsense. The Pi community is very likely to make use of one or both of the JTAG connectors in due course, as it will assist in debugging of programs with the help of an external development ...
by dwelch67
Wed May 30, 2012 9:00 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

What are the bogomips reported in /proc/cpuinfo? No, not running linux, no overhead, no interrupts to confuse the numbers, mess with the cache, just a handful of instructions in cache, actually counting the instructions being executed... What I meant to say is, this was bare metal, something along ...
by dwelch67
Wed May 30, 2012 1:50 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

dom wrote:What are the bogomips reported in /proc/cpuinfo?
No, not running linux, no overhead, no interrupts to confuse the numbers, mess with the cache, just a handful of instructions in cache, actually counting the instructions being executed...
by dwelch67
Tue May 29, 2012 5:49 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I timed a tight loop, two, three, four, etc instructions, a few million loops, with and without instruction cache. With instruction cache it was on a par with 250mips not 700mips. I checked the timers against a watch to understand their properties, counts per second. They match the documented 250mhz...
by dwelch67
Tue May 29, 2012 12:16 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I am not seeing 700Mhz on the arm. It is running at or on a par with the 250MHz system clock. Is there a place/register/etc that is used to bump the 250MHz clock or multiply it for the ARM?
by dwelch67
Mon May 28, 2012 10:27 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

more typos in the datasheet

page 196, it is an SP804 not AP804
page 197, bit 1, 32 bit counter not 23 bit counter
page 198, they cant both be at 0x40C, neither is 0x40C one is 0x410 the other 0x414
by dwelch67
Mon May 28, 2012 2:13 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I dont understand all the fuss about making a MAX232 board, If you're just using it as say a debug port or some other PC interface, then an FTDI chip is fine, but if you are interfacing to an actual RS232 device, then the MAX232 is critical. If serial comms can be made to work by bit-banging, rathe...
by dwelch67
Mon May 28, 2012 7:06 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

@dwelch67 Well done for getting it going, all those SD card insertions and removals are not fun. Very similar to the old days using the 8051 where it was a case of take the chip out of the socket, insert in ZIF socket of programmer, program, take out, put back into target board, test, oops, mistake...
by dwelch67
Mon May 28, 2012 3:53 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

Yes, I was active on the GP2X. Did the same thing there as here, not interested in writing linux apps, but instead getting down into the guts of the thing. I have not interfaced to a PS/2 keyboard or mouse. Looks like you have to supply 5V to power the keyboard. My understanding the serial interface...
by dwelch67
Sun May 27, 2012 2:55 pm
Forum: General discussion
Topic: Raspberry Pi boot process
Replies: 12
Views: 124238

Re: Raspberry Pi boot process

From what I understand and have confirmed the GPU then loads kernel.img, a binary image of ARM memory starting at physical address 0 from the ARM's perspective. And releases reset on the ARM. The downloads have a kernel.img which is basically linux, so there is a branch to 0x8000 (typical for linux)...
by dwelch67
Sun May 27, 2012 2:09 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

@dwelch67 Just a thought, why not also put the compiled img on github so that beginners that don't quite yet understand the whole process (or only use Windows) can also test and hopefully get interested. Done. At first I was thinking that if they want to use this tool they need a toolchain anyway, ...
by dwelch67
Sun May 27, 2012 2:05 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

@dwelch67 Well done for getting it going, all those SD card insertions and removals are not fun. Very similar to the old days using the 8051 where it was a case of take the chip out of the socket, insert in ZIF socket of programmer, program, take out, put back into target board, test, oops, mistake...
by dwelch67
Sun May 27, 2012 1:54 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

Please educate me/us on where I need to go or what I need to do to inform the right parties about errors in the datasheet.
by dwelch67
Sun May 27, 2012 6:36 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

I have a bootloader working now. http://github.com/dwelch67/raspberrypi/ You may find it ugly but it works. I didnt count the dozens/hundreds of sd card insertions it took to get to this point...no more! Hacking through the error(s) in the chip doc were quite painful.
by dwelch67
Sun May 27, 2012 4:23 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

That was quite painful. I figured it out though http://github.com/dwelch67/raspberrypi/uart01 This uses the mini uart, which is uart1 (TXD1, RXD1). Actually only TXD1, GPIO14. I dont understand all the fuss about making a MAX232 board, when there are at least three different flavors of ftdi boards a...
by dwelch67
Sun May 27, 2012 3:34 am
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

Does anyone have bare metal code that initializes the gpio/uart and transmits characters? This is driving me nuts...I can get the mini uart to spit something out, the other side isnt seeing it correctly (I have the proper level shifter on the host side). I can bit bang just fine. The full uart is no...
by dwelch67
Sat May 26, 2012 11:46 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

typos in the manual it appears

page 12 ..5044 is the IER not IIR, next page 5048 is the IIR not IER, right?

in the IER description those should all be R/W bits.
by dwelch67
Sat May 26, 2012 11:34 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

That was probably it. The docs say you should config the gpio first, that may have caused something on the rx, causing an interrupt. So I disabled the interrupts first, then disabled the uart, then was able to configure the gpio, and then configure and enable the uart. Not working yet, but over that...
by dwelch67
Sat May 26, 2012 10:34 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 37520

Re: Programming the ARM chip

Yes, all bare metal.

Using physical addressing, replace 0x7Exxxxxx with 0x20xxxxxx, can blink leds and talk to timers and such, moving toward bringing up one of the uarts. Prefer the mini uart to the full uart, but am having problems with the mini.

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