Difference between revisions of "AVR Drivers"

Of course you will need a flashlight driver circuit board first. The stock driver in some flashlights already has an Atmel driver on board. There are also several NANJG drivers available that include an Atmel TINY13A chip that can be programmed. ATtiyny13A can also be locked down (low fuse higher than 0x7F) so they can't be changed easily, but so far none seem to be. However, some variants of NANJG drivers use a PIC chip that can not be programmed with AVR tools, as well as Kaidomain driver doesn't use ATtiny13A. See [[Popular drivers]] to see some of the drivers people have been using. Most of these use current regulators to limit the current delivered to the LED while the Atmel chip itself turns the power on and off very quickly, leaving it on for full power, or flashing on and off quickly to simulate a lower mode. As the percentage of off time increases, the light gets dimmer. By setting the on-off cycles to a high frequency, the eye just sees this as a lower mode even when the LED is barely lit. This is called Pulse Width Modulation (PWM). By slowing the flashing more, you get a visible strobe mode or SOS modes. So essentially the Atmel chip is just a computer-controlled on-off switch.

The Atmel ATtiny13A has an 8-bit processor with 1 kb of flash memory, 64 bits of RAM, and 64 bits of EEPROM that can be written several thousand times. There are also settings called "fuses" which can be set or cleared.

[http://extremeelectronics.co.in/avr-tutorials/gui-software-for-usbasp-based-usb-avr-programmers/ '''eXtreme Burner - AVR'''] - Or if you do not like AVRDUDE and want something with GUI, you can try eXtreme Burner - AVR, download latest version at the bottom of the page under release. It can read/write (download/upload) and it also has the required driver for USBasp in the installation. If you only want to write a new firmware (already compiled Tido's, DrJones's, ...) this should be all you need. Does support ATtiny13A. Does not seem to write correctly nlite driver though. Either does not understand the hex format or ATtiny13A write support is bad. It reads and erases fine.

The programmer is 10 pins however which are set up one of two ways.

 

Old Style:

 

 

 

[[File:Ribbon.jpg|thumb|Old Style: The ribbon port at the end is disassembled and wire 8 is moved over to the 9th position]]Old Style: So Wire 1 (MOSI) of the ribbon cable from the programmer must attach to Pin 5 of the Atmel. Make sure you mark which side of the clip attaches to the top of the Atmel or everything will be misaligned next time you use it. Line up RST and SCK with their appropriate wires. But notice that MISO on the programmer is Wire number 9 and the ribbon only has 8 wires. You will need to disassemble the end of the ribbon cable at the controller end and move wire 8 over to the 9 position so that MISO lines up correctly.

Be aware that AVRDUDE does not officially support ATtiny13A and you will be using AVRDUDE with ATtiny13 setting "-p t13" instead of unsupported "-p t13a". The difference I found were lock bits when reading with ATtiny13A with it's proper setting (0xFC) compared to ATtiny13 setting (0x3C), important are the lowest 2 bits so the final lock bits are for both ATtiny13A and ATtiny13 setting reported correctly despite ATtiny13 setting reporting wrongly the higher bits when used on ATtiny13A chip. Otherwise it could work if you know what you're doing. On a typical Nanjg105C both lock bits are set (zeroed, 0xFC) and programming can only be done after chip erase that is automatically done by avrdude when new flash memory is written with -U parameter. That most likely also prevents reading of the original firmware, which can be read but due to lock bits may be read as garbage/nonsense and cannot be used as backup.

Use the software and hardware to download the existing program from the Atmel chip on the flashlight driver. You will need this if your programming doesn't work and you want to reset the driver to how it was originally. Get fuse settings too. (Actually it is not clear if getting original settings will do any good at all, so if you need a backup, try NLITE, mentioned in the next section).

When you upload new settings, you are wiping out the settings that the driver came with. Therefore if there are stars on the back that you have connected to get different mode combinations, that will be ignored (the stars are connected to legs of the Atmel chip that won't be used). It doesn't seem you can actually install old settings back into the driver. Instead you can install a [http://budgetlightforum.com/node/21465 similar one called NLITE located at BLF]. It is 3- or 4-mode with options for mode memory and order of modes (Low to High or High to Low) based on how the stars are soldered.

If you want a smaller code, use optimization for size for your compiler configuration. GCC uses "-Os" and you can find more useful optimizations and tricks via search, on [http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=90752 AVR Freaks] or elsewhere. Sometimes older GCC versions generate smaller code than the newer ones. Atmel uses AVR-GCC in it's toolchain as well, and currently it's the same version as in MHV AVR Tools.

[[File:Nanjg_105C._600.jpg|frame|center|Nanjg 105C. pin layout and traces with ATtiny13A.]]