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33 lines
1.2 KiB
Markdown
33 lines
1.2 KiB
Markdown
7 years ago
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Tutorial 03 - UART1, Auxilary mini UART
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=======================================
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It is time for the famous Hello World example. We're going to write on the UART1 first, as it's easier to program.
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NOTE: qemu does not redirect UART1 to terminal by default, only UART0!
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Gpio.h
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------
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We have a new header file. This defines the base MMIO address, and the GPIO controller's addresses. This file
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going to be very popular, as many device needs it.
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Uart.h, uart.c
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--------------
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A very minimal implementation.
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`uart_init()` initializes the device and maps it to the GPIO ports.
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`uart_send(c)` sends a character over the serial line.
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`uart_getc()` receives a character. The carrige return character (13) will be converted into a newline character (10).
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`uart_puts(s)` prints out a string. On newline, a carrige return character will also be sent (13 + 10).
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Main
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----
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First we have to call the uart initialization code. Then we say "Hello World!". If you've purchased an USB
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serial cable, you should see it on minicom's screen. After that every character typed in minicom will be
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echoed back. If you haven't turned off local echo, that means you'll see every pressed key twice.
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