X-Git-Url: http://git.linex4red.de/pub/USBasp.git/blobdiff_plain/141f24b4a13144a49fe21f7352b0e9d34962e2dd..5ba628d10b54d58d445896290ba9799bd76a73b3:/Bootloaders/Printer/BootloaderPrinter.txt diff --git a/Bootloaders/Printer/BootloaderPrinter.txt b/Bootloaders/Printer/BootloaderPrinter.txt index 71e9b2871..d9aa79686 100644 --- a/Bootloaders/Printer/BootloaderPrinter.txt +++ b/Bootloaders/Printer/BootloaderPrinter.txt @@ -54,6 +54,30 @@ * When the bootloader is running, the board's LED(s) will flash at regular intervals to distinguish the * bootloader from the normal user application. * + * \section Sec_Running Running the Bootloader + * + * On the USB AVR8 devices, setting the \c HWBE device fuse will cause the bootloader to run if the \c HWB pin of + * the AVR is grounded when the device is reset. + * + * The are two behaviours of this bootloader, depending on the device's fuses: + * + * If the device's BOOTRST fuse is set, the bootloader will run any time the system is reset from + * the external reset pin, unless no valid user application has been loaded. To initiate the bootloader, the + * device's external reset pin should be grounded momentarily. + * + * If the device's BOOTRST fuse is not set, the bootloader will run only if initiated via a software + * jump, or if the \c HWB pin was low during the last device reset (if the \c HWBE fuse is set). + * + * For board specific exceptions to the above, see below. + * + * \subsection SSec_XPLAIN Atmel Xplain Board + * Ground the USB AVR JTAG's \c TCK pin to ground when powering on the board to start the bootloader. This assumes the + * \c HWBE fuse is cleared and the \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board. + * + * \subsection SSec_Leonardo Arduino Leonardo Board + * Ground \c IO13 when powering the board to start the bootloader. This assumes the \c HWBE fuse is cleared and the + * \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board. + * * \section Sec_Installation Driver Installation * * This bootloader uses the Generic Text-Only printer drivers inbuilt into all modern operating systems, thus no @@ -163,12 +187,6 @@ * are unable to handle true plain-text printing. For best results, the low * level \c lpr command should be used to print new firmware to the bootloader. * - * \par After loading an application, it is not run automatically on startup. - * Some USB AVR boards ship with the BOOTRST fuse set, causing the bootloader - * to run automatically when the device is reset. In most cases, the BOOTRST - * fuse should be disabled and the HWBE fuse used instead to run the bootloader - * when needed. - * * \section Sec_Options Project Options * * The following defines can be found in this demo, which can control the demo behaviour when defined, or changed in value.