Minor documentation improvements.

[pub/USBasp.git] / Bootloaders / Printer / BootloaderPrinter.txt

diff --git a/Bootloaders/Printer/BootloaderPrinter.txt b/Bootloaders/Printer/BootloaderPrinter.txt
index 9a45fba..cfa51d4 100644 (file)
--- a/Bootloaders/Printer/BootloaderPrinter.txt
+++ b/Bootloaders/Printer/BootloaderPrinter.txt
@@ -54,6 +54,12 @@
  *  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
+ *
+ *  This bootloader is designed to be started via the HWB mechanism of the USB AVRs; ground the HWB pin (see device
+ *  datasheet) then momentarily ground /RESET to start the bootloader. This assumes the HWBE fuse is set and the BOOTRST
+ *  fuse is cleared.
+ *
  *  \section Sec_Installation Driver Installation
  *
  *  This bootloader uses the Generic Text-Only printer drivers inbuilt into all modern operating systems, thus no
@@ -110,6 +116,12 @@
  *  #define BOOTLOADER_ADDRESS_LENGTH          4
  *  \endcode
  *
+ *  From the application the API support of the bootloader can be detected by reading the FLASH memory bytes located at address
+ *  \c BOOTLOADER_MAGIC_SIGNATURE_START and comparing them to the value \c BOOTLOADER_MAGIC_SIGNATURE. The class of bootloader
+ *  can be determined by reading the FLASH memory bytes located at address \c BOOTLOADER_CLASS_SIGNATURE_START and comparing them
+ *  to the value \c BOOTLOADER_PRINTER_SIGNATURE. The start address of the bootloader can be retrieved by reading the bytes of FLASH
+ *  memory starting from address \c BOOTLOADER_ADDRESS_START.
+ *
  *  \subsection SSec_API_MemLayout Device Memory Map
  *  The following illustration indicates the final memory map of the device when loaded with the bootloader.
  *
@@ -148,11 +160,20 @@
  *  +----------------------------+ FLASHEND
  *  \endverbatim
  *
- *  Bootloaders reporting a device release revision number of 1.00 or greater are bootloader API enabled. From the application
- *  the API support of the bootloader can be detected by reading the FLASH memory bytes located at address \c BOOTLOADER_MAGIC_SIGNATURE_START
- *  and comparing them to the value \c BOOTLOADER_MAGIC_SIGNATURE. The class of bootloader can be determined by reading the
- *  FLASH memory bytes located at address \c BOOTLOADER_CLASS_SIGNATURE_START and comparing them to the value \c BOOTLOADER_PRINTER_SIGNATURE.
- *  The start address of the bootloader can be retrieved by reading the bytes of FLASH memory starting from address \c BOOTLOADER_ADDRESS_START.
+ *
+ *  \section Sec_KnownIssues Known Issues:
+ *
+ *  \par On Linux machines, new firmware fails to be sent to the device via CUPS.
+ *  Only a limited subset of normal printer functionality is exposed via the
+ *  bootloader, causing CUPS to reject print requests from applications that
+ *  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
  *