5b30e3d98d
USB_VBUS is not an alternate function, it is an additionnal function which is always enabled. If configured as an alternate function, it will draw current from VBUS.
README
This directory contains examples for the stm32f429i discovery board. The PCB should be labelled either MB1075B, and contains a user USB port, 2.4" QVGA TFT LCD display, 64Mbits external SDRAM and ST MEMS gyroscope.
http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/PF259090
Chuck McManis README
These examples are designed to demonstrate the use of libopencm3 with the STM32F4Discovery-DISCO board. This board has a 2.2" TFT LCD touchscreen on it, a MEMS gyroscope, and 8MB of SDRAM.
If you move through the examples in this order, the code from the previous example will be used in the next example:
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miniblink - verify that you can build a program, link it, and download it to the board. Blinks the GREEN LED at about 2Hz
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tick_blink - Clock setup, Systick setup, LED GPIO setup and blinking.
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usart_console - Program a USART on the board as a console (requires clonsing jumpers on your discovery board connecting USART1 to the programmer)
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usart_irq_console - Program a USART on the board as a console with an interrupt driven receive routine. This allows you to interrupt execution with ^C as you can on a Linux process.
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sdram - SDRAM setup, using the usb port as a console, which sets up the SDRAM
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spi - Serial Peripheral Interface example which talks to the MEMS gyroscope on the DISCO board.
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lcd-serial - Activates the TFT using the SPI port (serial) and holds a frame buffer in the SDRAM area.
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lcd - Now uses the new LCD "driver" peripheral to refresh the contents with what is in memory, very fast, write in memory and it appears on screen.
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dma2d - The 2D graphics accelerator device which displays various animations on the LCD using code from all of the previous examples.