Bare metal UART Driver (redefinition of printf to serial port)

Make sure that the initialize of the object has been initialized by using uboot.

 

// Serial register

// Uart0

# Defineulcon0 * (vu32 *) 0x7f005000) // UART channel 0-row control register

# Defineucon0 * (vu32 *) 0x7f005004) // UART channel 0 control register

# Defineufcon0 * (vu32 *) 0x7f005008) // UART channel 0 FIFO control register

# Defineumcon0 * (vu32 *) 0x7f00500c) // UART channel 0 Modem Control Register

# Defineutrstat0 * (vu32 *) 0x7f005010) // UART channel 0 sending/receiving status register

# Defineuerstat0 * (vu32 *) 0x7f005014) // UART channel 0 receives error Status Register

# Defineufstat0 * (vu32 *) 0x7f005018) // UART channel 0 FIFO Status Register

# Defineumstat0 * (vu32 *) 0x7f00501c) // UART channel 0 modem Status Register

# Defineutxh0 * (vu32 *) 0x7f005020) // UART channel 0 sending buffer register

# Defineurxh0 * (vu32 *) 0x7f005024) // UART channel 0 receiving buffer register

# Defineubrdiv0 * (vu32 *) 0x7f005028) // channel 0 baud rate division register

# Defineudivslot0 * (vu32 *) 0x7f00502c) // UART channel 0 division slot register

# Defineuintp0 * (vu32 *) 0x7f005030) // channel 0 Interrupt Processing Register

# Defineuintsp0 * (vu32 *) 0x7f005034) // UART channel 0 interrupt source Processing Register

# Defineuintm0 * (vu32 *) 0x7f005038) // UART channel 0 Interrupt Mask register

 

 

 

 

 

// Author: Chen

// Time created: 20120220

// Last modification time: 20120220

// Description

 

# Include "system. H"

# Include "UART. H"

# Include "maid"

 

 

 

 

//////////////////////////////////////// //////////////////////////

// Add the following code to support the printf function,

# If 1

 

# Include "stdio. H"

// Supported functions required by the standard library

Struct _ file

{

Inthandle;

};

/* File is typedef 'd in stdio. H .*/

File _ stdout;

// DEFINE _ sys_exit () to avoid half-Host Mode

_ Sys_exit (int x)

{

X = X;

}

// Redefine the fputc Function

Int fputc (int ch, file * F)

{

Uart0_sendbyte (u8) CH );

Returnch;

}

# Endif

 

 

 

Static const u16uart_speed [13] [2] ={{ 17,0x4924 },{ 858,0x4924 },{ 428,0x4924 },{ 285,0x4924 }, {4924x4924}, {4924x4924}, {4924x4924}, {x }, {4924x4924}, {4924 x}, {x }};

 

 

 

 

/*************************************** **************************************** **************************************** **

* Function: voiduart0_init (void)

* Function: Serial Port 0 Initialization

* Parameter: None

* Return value: None

* Dependency: underlying macro definition

* Author: Chen

* Duration: 20120220

* Last modification time: 20120220

* Description: Initialize the serial port 0.

**************************************** **************************************** **************************************** */

Void uart0_init (u8uart_speed)

{

Pclk_gate | = 1 <1; // uart0 selects the pclk clock, 66 MHz

Gpioa-> Con & = ~ (0xff); // clear the previous settings, gpioa0, gpioa1

Gpioa-> con | = (host | (host <4); // set gpioa0 and gpioa1 to UART

Ulcon0 = 0x3; // 8 bits per frame // clear settings // normal mode, no verification, 1 Stop bits

Ucon0 = (0x1 <2) | 0x1 | (2 <10); // clear the control register // set (pclk = 66 MHz) to a baud rate clock

Ufcon0 = 0; // disable FIFO

Umcon0 = 0; // disable AFC. The high level of nrts is invalid.

Ubrdiv0 = uart_speed [uart_speed] [0]; // set the baud rate integer

Udivslot0 = uart_speed [uart_speed] [1]; // you can specify the fractional part of the baud rate.

Uintp0 = 0; // disable uart0 interrupt

Uintsp0 = 0; // set the interrupt source

Uintm0 = 0; // disable interrupt shielding \

 

}

 

/*************************************** **************************************** **************************************** **

* Function: voiduart0_sendbyte (u8 data)

* Function: one byte is sent from the serial port 0.

* Parameter: sent data

* Return value: None

* Dependency: underlying macro definition

* Author: Chen

* Duration: 20120220

* Last modification time: 20120220

* Note: Use Serial Port 0 to send one byte

**************************************** **************************************** **************************************** */

Voiduart0_sendbyte (u8 data)

{

While (! (Utrstat0 & (1 <2); // wait for the sending buffer to be empty

Utxh0 = data; // write data to the sending Buffer

}

Now you can directly use printf to send data to the serial port.