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This makes the code pretty easily portable to other architectures if someone wants to make a more modern SIMM programmer. I also was pretty careful to split responsibilities of the different components and give the existing components better names. I'm pretty happy with the organization of the code now. As part of this change I have also heavily optimized the code. In particular, the read and write cycle routines are very important to the overall performance of the programmer. In these routines I had to make some tradeoffs of code performance versus prettiness, but the overall result is much faster programming. Some of these performance changes are the result of what I discovered when I upgraded my AVR compiler. I discovered that it is smarter at looking at 32-bit variables when I use a union instead of bitwise operations. I also shaved off more CPU cycles by carefully making a few small tweaks. I added a bypass for the "program only some chips" mask, because it was adding unnecessary CPU cycles for a feature that is rarely used. I removed the verification feature from the write routine, because we can always verify the data after the write chunk is complete, which is more efficient. I also added assumptions about the initial/final state of the CS/OE/WE pins, which allowed me to remove more valuable CPU cycles from the read/write cycle routines. There are also a few enormous performance optimizations I should have done a long time ago: 1) The code was only handling one received byte per main loop iteration. Reading every byte available cut nearly a minute off of the 8 MB programming time. 2) The code wasn't taking advantage of the faster programming command available in the chips used on the 8 MB SIMM. The end result of all of these optimizations is I have programming time of the 8 MB SIMM down to 3:31 (it used to be 8:43). Another minor issue I fixed: the Micron SIMM chip identification wasn't working properly. It was outputting the manufacturer ID again instead of the device ID.
28 lines
2.0 KiB
Plaintext
28 lines
2.0 KiB
Plaintext
/** \file
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*
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* This file contains special DoxyGen information for the generation of the main page and other special
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* documentation pages. It is not a project source file.
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*/
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/** \page Page_ProgrammingApps Programming an Application into a USB AVR
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*
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* Once you have built an application, you will need a way to program in the resulting ".HEX" file (and, if your
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* application uses EEPROM variables with initial values, also a ".EEP" file) into your USB AVR. Normally, the
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* reprogramming of an AVR device must be performed using a special piece of programming hardware, through one of the
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* supported AVR programming protocols - ISP, HVSP, HVPP, JTAG or dW. This can be done through a custom programmer,
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* a third party programmer, or an official Atmel AVR tool - for more information, see the Atmel.com website.
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*
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* Alternatively, you can use the bootloader. From the Atmel factory, each USB AVR comes preloaded with the Atmel
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* DFU (Device Firmware Update) class bootloader, a small piece of AVR firmware which allows the remainder of the
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* AVR to be programmed through a non-standard interface such as the serial USART port, SPI, or (in this case) USB.
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* Bootloaders have the advantage of not requiring any special hardware for programming, and cannot usually be erased
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* or broken without an external programming device. They have disadvantages however; they cannot change the fuses of
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* the AVR (special configuration settings that control the operation of the chip itself) and a small portion of the
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* AVR's FLASH program memory must be reserved to contain the bootloader firmware, and thus cannot be used by the
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* loaded application. Atmel's DFU bootloader is either 4KB (for the smaller USB AVRs) or 8KB (for the larger USB AVRs).
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*
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* If you wish to use the DFU bootloader to program in your application, refer to your DFU programmer's documentation.
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* Atmel provides a free utility called FLIP which is USB AVR compatible, and an open source (Linux compatible)
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* alternative exists called "dfu-programmer".
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*/
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