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Diffstat (limited to 'libmaple/usb/README')
| -rw-r--r-- | libmaple/usb/README | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/libmaple/usb/README b/libmaple/usb/README deleted file mode 100644 index 035b566..0000000 --- a/libmaple/usb/README +++ /dev/null @@ -1,37 +0,0 @@ -The USB submodule of libmaple is responsible for: - initilizing the usb peripheral, scaling the peripheral clocks appropriately, - enabling the interrupt channels to usb, defining the usb isr, resetting the usb - disc pin (used to tell the host were alive). Additionally, the usb submodule defines - the virtual com port usb applications that is available to all user sketches via Usb.print() - and others. - - Currently, the USB submodule relies on the low level core library provided by ST to access the - usb peripheral registers and implement the usb transfer protocol for control endpoint transfers. - The high level virtual com port application is unfortunately hard to untangle from this low level - dependence, and when a new USB core library is written (to nix ST dependence) changes will likely - have to be made to virtual com application code. Ideally, the new core library should mimick the - form of MyUSB (LUFA), since this library (USB for AVR) is growing in popularity and in example - applications. - - The virtual com port serves two important purposes. 1) is allows serial data transfers between - user sketches an a host computer. 2) is allows the host machine to issue a system reset by - asserting the DTR signal. After reset, Maple will run the DFU bootloader for a few seconds, - during which the user can begin a DFU download operation ('downloads' application binary into - RAM/FLASH). This without this virtual com port, it would be necessary to find an alternative means - to reset the chip in order to enable the bootloader. - - If you would like to develop your own USB application for whatever reason (uses faster isochronous - enpoints for streaming audio, or implements the USB HID or Mass Storage specs for examples) then - ensure that you leave some hook for resetting Maple remotely in order to spin up the DFU bootloader. - Please make sure to give yourself a unique vendor/product ID pair in your application, as some - operating systems will assign a host-side driver based on these tags. - - It would be possible to build a compound usb device, that implements endpoints for both the virtual - COM port as well as some other components (mass sotrage etc.) however this turns out to be a burden - from the host driver side, as windows and *nix handle compound usb devices quite differently. - - Be mindful that running the usb application isnt "free." The device must respond to periodic bus - activity (every few milliseconds) by servicing an ISR. Therefore the usb application should be disabled - inside of timing critical applications. In order to disconnect the device from the host, the USB_DISC - pin can be asserted (on Maple v1,2,3 this is GPIOC,12). Alternatively, the NVIC can be directly configured - to disable the USB LP/HP IRQ's
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