UART 4 Problem

Posted on May 17, 2011 at 13:19

Im using UART4 on the STM32F103Ze.

As soon as an UART4 RX Interrupt occurs, a hard fault exception occurs

Hard fault Status Register = 0x40000000 (bit 30 is set)

As far as I know this indicates one of the following faults:

1. Bus fault,

2. Memory management fault

3. Usage fault

Below is my code.

UART initialization

RCC->APB1ENR |= RCC_APB1Periph_UART4; //Enable clock for USART4

UART4->BRR = 0x0EA6; //Set baudrate

UART4->CR1 = 0x00000000; //Set Data, Stop bits & Flow control

UART4->CR1 |= (USART_CR1_RE | USART_CR1_TE); //RX, TX enable

UART4->CR1 |= 0x20; //RXNE Interrupt Enable

UART4->CR1 |= USART_CR1_UE; //USART enable

Interrupt initialization

NVIC_InitStructure.NVIC_IRQChannel = UART4_IRQChannel;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

Interrupt

void UART4_IRQHandler(void)

{

u8 Rx_Char;

if(UART4->SR & USART_FLAG_RXNE) //RX Character

{

UART4->SR &= ~USART_FLAG_RXNE; //Clear interrupt flag

Rx_Char = UART4->DR & 0xFF;

UART4_Flag = 0xFF;

}

}

I used the same code for USART1, 2 and 3, all working.

Posted on May 17, 2011 at 13:19

Hi St7

According to the User Manual on p36, UART4 is on APB1.

Is there something else that I am missing?

Thanx

Posted on May 17, 2011 at 13:19

Quote:

Ah, fuck, code tag doesn't work for this... code :p

I know - it's pretty useless having a 'CODE' tag that doesn't actually work with source code, isn't it?!

Who chose this forum software with such an obvious and fundamental flaw?!

Previously noted nearly a year ago:

http://www.st.com/mcu/forums-cat-7210-23.html

[ This message was edited by: st7 on 30-07-2009 09:47 ]

See also:

http://www.st.com/mcu/forums-cat-8699-23.html

[ This message was edited by: st7 on 30-07-2009 09:48 ]

Posted on May 17, 2011 at 13:19

You could install a hard fault handler, maybe it'll provide some hint.

ie. something like (made for GCC):

void __attribute__ ((naked)) HardFaultException()

{

asm volatile (

''mov r1, #1\n\t''

''b generic_exception_handler\n\t''

);

}

/*

TST LR, #4

ITE EQ

MRSEQ R0, MSP

MRSNE R0, PSP

B hard_fault_handler_c

*/

void __attribute__ ((naked)) generic_exception_handler()

{

asm volatile (

''tst lr, #4\n\t''

''ite eq\n\t''

''mrseq r0, msp\n\t''

''mrsne r0, psp\n\t''

''stmfd sp!, {r4-r11}\n\t''

''mov r2, sp\n\t''

''b generic_exception_handler_c\n\t''

);

}

/* my precious debugging function

* HardFault is triggered on ie. invalid memory access.

* note: on IMPRECISERR, this doesn't help much. it just means that some

* invalid access occured but possibly before (after/prediction?) PC

*/

void generic_exception_handler_c(unsigned int *oldstack, int exception,

unsigned int *newstack)

{

int oldstack_valid = (oldstack >= (unsigned int*)&_sdata && oldstack < newstack);

volatile int ffs = 1;

usart_setflag(USART_DEBUG, FLAG_DIRECT, 1);

if (usart_getflag(USART_DEBUG, FLAG_ACTIVE))

while (1);

printf(''%s was caled, dumping regs:\n'', exception_strings[exception]);

if (oldstack_valid) {

printf(''r0\t0x%08x\t%i\n'', oldstack[0], oldstack[0]);

printf(''r1\t0x%08x\t%i\n'', oldstack[1], oldstack[1]);

printf(''r2\t0x%08x\t%i\n'', oldstack[2], oldstack[2]);

printf(''r3\t0x%08x\t%i\n'', oldstack[3], oldstack[3]);

} else {

printf(''sp\t0x%08x\t%i\n'', (unsigned int)oldstack, (unsigned int)oldstack);

printf(''sp is invalid, so some registers are missing\n'');

}

printf(''r4\t0x%08x\t%i\n'', newstack[0], newstack[0]);

printf(''r5\t0x%08x\t%i\n'', newstack[1], newstack[1]);

printf(''r6\t0x%08x\t%i\n'', newstack[2], newstack[2]);

printf(''r7\t0x%08x\t%i\n'', newstack[3], newstack[3]);

printf(''r8\t0x%08x\t%i\n'', newstack[4], newstack[4]);

printf(''r9\t0x%08x\t%i\n'', newstack[5], newstack[5]);

printf(''r10/sl\t0x%08x\t%i\n'', newstack[6], newstack[6]);

printf(''r11/fp\t0x%08x\t%i\n'', newstack[7], newstack[7]);

if (oldstack_valid) {

printf(''r12/ip\t0x%08x\t%i\n'', oldstack[4], oldstack[4]);

printf(''sp\t0x%08x\t%i\n'', (unsigned int)oldstack, (unsigned int)oldstack);

printf(''lr\t0x%08x\t%i\n'', oldstack[5], oldstack[5]);

printf(''pc\t0x%08x\t%i\n'', oldstack[6], oldstack[6]);

printf(''psr\t0x%08x\t%i\n'', oldstack[7], oldstack[7]);

}

printf(''CFSR\t0x%08x\n'', *(unsigned int*)0xe000ed28);

printf(''HFSR\t0x%08x\n'', *(unsigned int*)0xe000ed2c);

printf(''DFSR\t0x%08x\n'', *(unsigned int*)0xe000ed30);

printf(''MMAR\t0x%08x\n'', *(unsigned int*)0xe000ed34);

printf(''BFAR\t0x%08x\n'', *(unsigned int*)0xe000ed38);

printf(''AFSR\t0x%08x\n'', *(unsigned int*)0xe000ed3c);

printf(''\nhalted\n'');

while (ffs)

;

}

Ah, fuck, code tag doesn't work for this... code :p