From: Stephan Baerwolf Date: Mon, 17 Sep 2012 17:53:22 +0000 (+0000) Subject: Finally a correct and translated schematics recommendation X-Git-Tag: v0.7~4 X-Git-Url: http://git.linex4red.de/pub/USBaspLoader.git/commitdiff_plain/ee50c74c0cd7e34df64773b0ca9e614de1f56518 Finally a correct and translated schematics recommendation Signed-off-by: Stephan Baerwolf --- diff --git a/Schematics.txt b/Schematics.txt index 7a1e0f5..17dafd5 100644 --- a/Schematics.txt +++ b/Schematics.txt @@ -1,20 +1,53 @@ -Designed fuer Atmega8 (with external crystal with 16MHz) -^^^^^^^^^^^^^^^^^^^^^ +Default settings are designed for atmega8 (with external 16MHz crystal) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +First you have to bring the USBaspLoader into the MCU by some conventional +way, for example by using the traditional LPT1 on an old computer: --> avrdude -p m8 -c pony-stk200 -e -U flash:w:bootloaderfirmware.hex <-- -USB-Schematics wie in VUSB mit ZenerDiode +Or via an already existing MCU, flashed with the USBasp Programmer: + +--> avrdude -p m8 -c usbasp -e -U flash:w:bootloaderfirmware.hex <-- + + +If you already have an existing (and spminterface supporting) USBaspLoader +flashed and you just want to update the loader to new features/version, +you can use its integrated update-feature by flashing the update-firmware. +After executing it at least one time, it will replace the old loader with +the new one contained within the update. Then you can start flashing other +firmwares, again... + + +Since the atmega8 (used as default) is 5V, the recommended USB-Schematics +should use zeners. (for more information see the VUSB designrecommendation +with the two 1N4729 zener diodes as level limiter...) +Because it is most unlikely to use the atmega8 as analogous comperator +(there are much more cheap ICs for this), it is recommended to use those +PINs for USB-Interface (this is the default, but it can be changed): + +USBD+ (green) --> PIN4 (PD2) +USBD- (white) --> PIN12 (PD6, AIN0) + +BUTTON SWITCH --> PIN13 (PD7, AIN1) + +The bootloader bootup logic has changed a little bit, compared to the +original JUMPER-logic within original USBaspLoader 2010-07-27. +However most of the new logic is compatible with old JUMPER schematics: + +When RESET/PowerUP while BUTTON is pressed (PIN13 is low), then bootloader +will start. Even if the BUTTON is release after this and PIN13 becomes HIGH, +the bootloader stays active and listens to commands as long as the BUTTON +will be pressed (and so PIN13 becomes low) again... + +If the BUTTON is NOT pressed at RESET/PowerUP, or pressed again while +in bootloader, the user defined firmware is started. + -USBD+ (gruen) --> PIN4 (PD2) -USBD- (weiss) --> PIN12 (AIN0) -TASTER --> PIN13 (AIN1) -Wenn RESET/PowerUP UND Taster gedrueckt (PIN13 LOW) dann startet Bootloader. -Wenn dieser Taster nach dem ersten loslassen erneu gedrueckt wird beendet -sich der Loader nach Fertigstellung ggf. noch offener Operationen und -startet die programmierte Firmware. +for default atmega8 recommended MCU-settings are: -empfohlene LFUSE: 0x1f -empfohlene HFUSE: 0xc0 -empfohlene LOCK : 0x3f (unveraendert - bootsection wird per software geschuetzt) +LFUSE: 0x1f +HFUSE: 0xc0 +LOCK : 0x3f (unchanged - the bootsection is proceteced via loader software)