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adding uart03. same as uart02 except mostly thumb instead of ARM

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This commit is contained in:
David Welch
2012-05-27 10:33:46 -04:00
parent e188f43690
commit 507949cb1b
5 changed files with 226 additions and 0 deletions
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32
uart03/Makefile Normal file
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ARMGNU ?= arm-none-eabi
COPS = -mthumb -Wall -O2 -nostdlib -nostartfiles -ffreestanding
all : uart03.hex
clean :
rm -f *.o
rm -f *.bin
rm -f *.hex
rm -f *.elf
rm -f *.list
rm -f *.img
novectors.o : novectors.s
$(ARMGNU)-as novectors.s -o novectors.o
uart03.o : uart03.c
$(ARMGNU)-gcc $(COPS) -c uart03.c -o uart03.o
uart03.hex : memmap novectors.o uart03.o
$(ARMGNU)-ld novectors.o uart03.o -T memmap -o uart03.elf
$(ARMGNU)-objdump -D uart03.elf > uart03.list
$(ARMGNU)-objcopy uart03.elf -O binary uart03.bin
$(ARMGNU)-objcopy uart03.elf -O ihex uart03.hex

30
uart03/README Normal file
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See the top level README for information on where to find the
schematic and programmers reference manual for the ARM processor
on the raspberry pi.
Based on uart02, the difference is that this is primarily thumb code
instead of ARM. ARM in this case meaning the traditional 32 bit
instruction set and thumb meaning the traditional 16 bit instruction
subset. Thumb2 has confused/blurred those definitions though.
(thumb2 is a mostly 32 bit extension to the thumb instruction set using
formerly undefined instructions to create variable word length instructions).
You have two choices you can use my bootloader with the uart03.hex file
or copy the uart02.bin file to (overwrite the) kernel.img on your raspi
sd card. (might want to back up that file if you want to go back to
running linux with it later, or download a replacement from the net).
You will need something like this
http://www.sparkfun.com/products/718
to connect to the uart pins on the raspi. Do not connect the raspberry
pi pins directly to a com port on a computer you will fry the board.
The above board happens to have pins in the same order as the raspberry
pi. On connector P1 on the raspberry pi connect pin 6 to ground on the
usb to serial board. Pin 8 on P1 to RX on the usb to serial board, and
pin 10 on P1 to TX on the usb to serial board.
Using a dumb terminal (minicom) 115200 board No parity 8 bits 1 stop
bit, no flow control (might have to exit minicom and start again for
the flow control setting to take). What you type on the dumb terminal
echos back.

12
uart03/memmap Normal file
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MEMORY
{
ram : ORIGIN = 0x00000000, LENGTH = 0x1000
}
SECTIONS
{
.text : { *(.text*) } > ram
.bss : { *(.bss*) } > ram
}

36
uart03/novectors.s Normal file
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.globl _start
_start:
b reset
reset:
ldr sp,stack_start
ldr r0,thumb_start_add
bx r0
stack_start: .word 0x1000
thumb_start_add: .word thumb_start
.word 0
.word 0
.thumb
.thumb_func
thumb_start:
bl notmain
hang: b hang
.thumb_func
.globl PUT32
PUT32:
str r1,[r0]
bx lr
.thumb_func
.globl GET32
GET32:
ldr r0,[r0]
bx lr
.thumb_func
.globl dummy
dummy:
bx lr

116
uart03/uart03.c Normal file
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//-------------------------------------------------------------------------
//-------------------------------------------------------------------------
extern void PUT32 ( unsigned int, unsigned int );
extern unsigned int GET32 ( unsigned int );
extern void dummy ( unsigned int );
#define GPFSEL1 0x20200004
#define GPSET0 0x2020001C
#define GPCLR0 0x20200028
#define GPPUD 0x20200094
#define GPPUDCLK0 0x20200098
#define AUX_ENABLES 0x20215004
#define AUX_MU_IO_REG 0x20215040
#define AUX_MU_IER_REG 0x20215044
#define AUX_MU_IIR_REG 0x20215048
#define AUX_MU_LCR_REG 0x2021504C
#define AUX_MU_MCR_REG 0x20215050
#define AUX_MU_LSR_REG 0x20215054
#define AUX_MU_MSR_REG 0x20215058
#define AUX_MU_SCRATCH 0x2021505C
#define AUX_MU_CNTL_REG 0x20215060
#define AUX_MU_STAT_REG 0x20215064
#define AUX_MU_BAUD_REG 0x20215068
//GPIO14 TXD0 and TXD1
//GPIO15 RXD0 and RXD1
//alt function 5 for uart1
//alt function 0 for uart0
//((250,000,000/115200)/8)-1 = 270
//------------------------------------------------------------------------
void uart_putc ( unsigned int c )
{
while(1)
{
if(GET32(AUX_MU_LSR_REG)&0x20) break;
}
PUT32(AUX_MU_IO_REG,c);
}
//------------------------------------------------------------------------
void hexstrings ( unsigned int d )
{
//unsigned int ra;
unsigned int rb;
unsigned int rc;
rb=32;
while(1)
{
rb-=4;
rc=(d>>rb)&0xF;
if(rc>9) rc+=0x37; else rc+=0x30;
uart_putc(rc);
if(rb==0) break;
}
uart_putc(0x20);
}
//------------------------------------------------------------------------
void hexstring ( unsigned int d )
{
hexstrings(d);
uart_putc(0x0D);
uart_putc(0x0A);
}
//------------------------------------------------------------------------
int notmain ( void )
{
unsigned int ra;
PUT32(AUX_ENABLES,1);
PUT32(AUX_MU_IER_REG,0);
PUT32(AUX_MU_CNTL_REG,0);
PUT32(AUX_MU_LCR_REG,3);
PUT32(AUX_MU_MCR_REG,0);
PUT32(AUX_MU_IER_REG,0);
PUT32(AUX_MU_IIR_REG,0xC6);
PUT32(AUX_MU_BAUD_REG,270);
ra=GET32(GPFSEL1);
ra&=~(7<<12); //gpio14
ra|=2<<12; //alt5
ra&=~(7<<15); //gpio15
ra|=2<<15; //alt5
PUT32(GPFSEL1,ra);
PUT32(GPPUD,0);
for(ra=0;ra<150;ra++) dummy(ra);
PUT32(GPPUDCLK0,(1<<14)|(1<<15));
for(ra=0;ra<150;ra++) dummy(ra);
PUT32(GPPUDCLK0,0);
PUT32(AUX_MU_CNTL_REG,3);
hexstring(0x12345678);
while(1)
{
while(1)
{
if(GET32(AUX_MU_LSR_REG)&0x01) break;
}
ra=GET32(AUX_MU_IO_REG);
//while(1)
//{
//if(GET32(AUX_MU_LSR_REG)&0x20) break;
//}
PUT32(AUX_MU_IO_REG,ra);
}
return(0);
}
//-------------------------------------------------------------------------
//-------------------------------------------------------------------------