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Activating ARM9 with a working OS » History » Version 4

Vanč Levstik, 10.12.2010 03:20

1 1 Aleksander Bešir 
h1. Activating ARM9 with a working OS
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h2. Basic concept





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h3. Hardware





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!http://www.shrani.si/f/2A/128/4kJtfyhW/arm-picture.jpg!





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We will be using FRI-SMS 32-bit microcontroller based on AT91SAM9620 chip from ARM9 family. It has fast ROM and RAM memories and embedds  Ethernet MAC, one USB Device Port, and a USB Host controller. It also integrates several standard peripherals, such as the USART, SPI, TWI, Timer 





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Counters, Synchronous Serial Controller, ADC and MultiMedia Card Interface. 





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More about microcontroller can be found in "Manual":http://laps.fri.uni-lj.si/fri-sms/datoteke/AT91SAM9260.pdf





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h3. Software





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For programming the device we will be using AT91 In-System programmer "SAM-BA":http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3883.





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We will also use "U-BOOT":http://www.denx.de/wiki/U-Boot as a second-step bootloader.





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Our operating system will be Linux, kernel version 2.6.27.





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h2. Installing OS





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h3. Concept





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FRI-SMS is built, so it boots from integrated ROM memory. It looks for bootloader into serial flash memory, if it is found it loads into internal SDRAM. This first-step bootloader then sets SDRAM controller and loads second-step bootloader(U-BOOT) into external SDRAM end executes it.





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Second-step bootloader takes care of other microcontroller settings and runs the OS.





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If bootloader is not found in ROM it searches for bootloader thtrough USB interface and then through RS232 interface and waits there in loop.





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h3. Loading software into flash ROM memory





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* Installing SAM-BA





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       After installing SAM-BA we have to set the drivers correctly. SAM-BA is based on setting connection throuogh COM port, so we have to install a  driver which sets the PC, so it recognizes the USB as COM port. SAM-BA install includes a driver, but it does not work on x64 





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based operating systems such as Windows Vista 64-bit and Windows 7 64-bit. Attached is a modified driver, so it works on those systems (tested on Windows 7).





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With SAM-BA we establish a connection between PC and FRI-SMS, then we enable DataFlash on external flash memory.





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# First we load second-step bootloader U-BOOT from address *0x8400* onward





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# Next step is Linux OS kernel, which we load on address *0x42000*





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# Last step is first-step bootloader, which must be loaded last, because we can't load any more files after we load first step loader (at least until system restore)