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by dwelch67
Wed May 30, 2012 9:00 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 122858

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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: 36036

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.
by dwelch67
Sat May 26, 2012 10:01 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 36036

Re: Programming the ARM chip

And getting hangs talking to the mini-uart. I write a 0x1 to the AUX_ENABLES then try to write to the control register in the mini uart and that appears to cause a hang. Am I missing something?
by dwelch67
Sat May 26, 2012 9:42 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 36036

Re: Programming the ARM chip

I am struggling to turn off the pull down for GPIO14 and 15 (UART). from the diagram in the docs it implies that pull up/down are indpendent of function/alternate function. is that correct? If I have switched to the alternate function for the GPIO do I need to modify the pull up/down? What I am doin...
by dwelch67
Sat May 26, 2012 6:05 pm
Forum: Other programming languages
Topic: Programming the ARM chip
Replies: 134
Views: 36036

Re: Programming the ARM chip

Got my (first) raspberry pi yesterday http://github.com/dwelch67/raspberrypi I have just started a set of bare metal arm programming examples for the rpi. Quite disappointed that the arm jtag is not easier to get to. If nothing else a very small kernel.img that changes gpio pins to alternate functio...

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