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manual:usb_demo [2018/07/27 23:28]
voorburg [Notes]
manual:usb_demo [2019/09/24 22:03] (current)
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 ===== Notes ===== ===== Notes =====
  
-When using USB as the communication interface, the bootloader stays active a bit longer than usual. This extension time can be configured via configuration macro BOOT_COM_USB_BACKDOOR_EXTENSION_MS in “blt_conf.h”. This extra time is needed for the USB device to enumerate on the PC, to the point that it can detect firmware update requests. ​+When using USB as the communication interface, the bootloader stays active a bit longer than usual. This extension time can be configured via configuration macro BOOT_COM_USB_BACKDOOR_EXTENSION_MS in “blt_conf.h”. This extra time is needed for the USB device to enumerate on the PC, to the point that the bootloader ​can detect firmware update requests. ​
  
 This time might not be long enough in the situation where the USB driver was just installed on the host PC and the USB enumeration takes place for the first time. For this reason it is highly recommended to implement an additional method to force the bootloader to stay active. This latter case happens when the CpuUserProgramStartHook()-function is enabled and returns BLT_FALSE. All OpenBLT demo programs that support firmware updates via USB have such a method implemented for forcing the bootloader to stay active. Typically if a push-button stays pressed for a few seconds during and after a microcontroller reset. Refer to the CpuUserProgramStartHook()-function ​ in the bootloader demo programs for more details. This time might not be long enough in the situation where the USB driver was just installed on the host PC and the USB enumeration takes place for the first time. For this reason it is highly recommended to implement an additional method to force the bootloader to stay active. This latter case happens when the CpuUserProgramStartHook()-function is enabled and returns BLT_FALSE. All OpenBLT demo programs that support firmware updates via USB have such a method implemented for forcing the bootloader to stay active. Typically if a push-button stays pressed for a few seconds during and after a microcontroller reset. Refer to the CpuUserProgramStartHook()-function ​ in the bootloader demo programs for more details.
  
manual/usb_demo.txt · Last modified: 2019/09/24 22:03 (external edit)