UART ISR

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originally posted by rugbybloke@Sep 2 2005, 10:02 AM

if you look in the directory altera\kits\nios2\components\altera_avalon_uart there is a driver for the uart, both interrupt driven and non-interrupt driven. i suspect that your problem is that the uart driver is automatically installed on your system, so it is handling the isr. you will be able to tell by looking in alt_sys_init.c, but you should probably read chapter 4 and 5 of the nios ii software developers handook to understand what alt_sys_init.c is first.

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I have looked into the codes you say,

but i want to use as less as possible nios II API because I want to

understand what I'm doing so I've registered by hand the IRQ

associated to the IRQ mapped to the UART in the Hardware Platform.

As I can read on datasheet i can see that

" The UART core outputs a single IRQ signal to the Avalon interface, which

can connect to any master peripheral in the system, such as a Nios II

processor. The master peripheral must read the status register to

determine the cause of the interrupt.

Every interrupt condition has an associated bit in the status register

and an interrupt-enable bit in the control register. When any of the

interrupt conditions occur, the associated status bit is set to 1 and

remains set until it is explicitly acknowledged. The IRQ output is asserted

when any of the status bits are set while the corresponding interruptenable

bit is 1. A master peripheral can acknowledge the IRQ by clearing

the status register.

At reset, all interrupt-enable bits are set to 0; therefore, the core cannot

assert an IRQ until a master peripheral sets one or more of the interruptenable

bits to 1.

All possible interrupt conditions are listed with their associated status

and control (interrupt-enable) bits in Table 6–5 on page 6–16 and

Table 6–6 on page 6–18. Details of each interrupt condition are provided

in the status bit descriptions. "

so the IRQ should be setted automatically by the CPU and the only think

I have to do is to register the irq to a custom IRQ handler function. There

is an example on the datasheet for the PIOs Peripheral.

I've looked into my alt_sys_init.c and I've found these:

void alt_sys_init( void )

{

ALTERA_AVALON_TIMER_INIT( TIMER, timer );

ALTERA_AVALON_JTAG_UART_INIT( JTAG_UART_0, jtag_uart_0 );

ALTERA_AVALON_SYSID_INIT( SYSID, sysid );

ALTERA_AVALON_CFI_FLASH_INIT( EXT_FLASH, ext_flash );

ALTERA_AVALON_LAN91C111_INIT( LAN91C111, lan91c111 );

ALTERA_AVALON_LCD_16207_INIT( LCD, lcd );

ALTERA_AVALON_UART_INIT( SERIALE_INT, seriale_int );

ALTERA_AVALON_UART_INIT( SERIALE_EXT, seriale_ext );

ALTERA_AVALON_UART_INIT( SERIALE_FUT, seriale_fut );

}

yes I&#39;ve 3 UARTS.... http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif ....

now if I recall the API, (but I wish that there is another method) how I have to do ???

there is any kind of example?

shadowice

<div class='quotetop'>QUOTE </div>

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ALTERA_AVALON_UART_INIT( SERIALE_INT, seriale_int );

ALTERA_AVALON_UART_INIT( SERIALE_EXT, seriale_ext );

ALTERA_AVALON_UART_INIT( SERIALE_FUT, seriale_fut );[/b]

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Your problem is exactly as I diagnosed the lines above are initialising the driver for each of your UARTs so when the interrupt goes off for one of your UARTs the driver interrupt handler get&#39;s called and your ISR does not get a look in. There is no easy method to turn off the drivers at present you will have to remove the _INIT and _INSTANCE macros from alt_sys_init.c. The problem is that this is an auto generated file which will be re-generated under your feet.

You would be much better off using the provided driver and if you don&#39;t understand it step through it. Otherwise you will have to start from the alt_main entry point example which hands you complete control of the machine, with no drivers etc. This does have drawbacks though which are coverred in the manual.

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originally posted by rugbybloke@Sep 2 2005, 11:24 AM

<div class='quotetop'>quote

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altera_avalon_uart_init( seriale_int, seriale_int );

altera_avalon_uart_init( seriale_ext, seriale_ext );

altera_avalon_uart_init( seriale_fut, seriale_fut );

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Your problem is exactly as I diagnosed the lines above are initialising the driver for each of your UARTs so when the interrupt goes off for one of your UARTs the driver interrupt handler get&#39;s called and your ISR does not get a look in. There is no easy method to turn off the drivers at present you will have to remove the _INIT and _INSTANCE macros from alt_sys_init.c. The problem is that this is an auto generated file which will be re-generated under your feet.

You would be much better off using the provided driver and if you don&#39;t understand it step through it. Otherwise you will have to start from the alt_main entry point example which hands you complete control of the machine, with no drivers etc. This does have drawbacks though which are coverred in the manual.[/b]

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so there is no simply way to drive UART using low level functions such as

for the PIO component.

I have to understand how drive the ISR function using its APIs.... but

the only think I don&#39;t understand is HOW recall the IRQ using the auto

generated function by NIOS-II IDE.

thank you

shadowice

Now SEEMS!! to be functioning...

http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/laugh.gif

I have noted that the IRQ call is not flushed after the ISR execution... http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/mad.gif

In order to explain to the community I cut and paste the simple code I have created

for my UART "SERIALE_EXT" peripheral

I hope It will be usefull:

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

# include <stdio.h># include "altera_avalon_uart_regs.h"# include "altera_avalon_uart.h"# include "sys/alt_irq.h"# include "system.h"

// Register the istance into the CPU //

ALTERA_AVALON_UART_INSTANCE( SERIALE_EXT, seriale_ext );

void handle_seriale_ext_interrupt (void *context, alt_u32 id);

int _serial_rcv_exception;

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

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

// MAIN Function //

int main (void)

{

// Initialize the IRQ on the UART selected //

ALTERA_AVALON_UART_INIT ( SERIALE_EXT, seriale_ext );

// Recast the _edge_capture pointer to match the alt_irq_register()

// function prototype.

void* serial_rcv_exception_ptr = (void*) &_serial_rcv_exception;

// Register the interrupt handler. //

alt_irq_register(SERIALE_EXT_IRQ, serial_rcv_exception_ptr, handle_seriale_ext_interrupt);

} // END MAIN //

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

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

// UART ISR Handling //

void handle_seriale_ext_interrupt (void *context, alt_u32 id)

{

// Cast context to _edge_capture&#39;s type.

// It is important to keep this volatile,

// to avoid compiler optimization issues.

volatile int* serial_rcv_exception_ptr = (volatile int*) context;

// Store the value in the Serial exception register in *context. //

*serial_rcv_exception_ptr = IORD_ALTERA_AVALON_UART_STATUS(SERIALE_EXT_BASE);

// Reset the Serial exception register. //

IOWR_ALTERA_AVALON_UART_STATUS(SERIALE_EXT_BASE, (*serial_rcv_exception_ptr & 0xFF7F));

// Print a simple message on the STDOUT peripheral //

printf("\rISR HAS BEEN\nEXECUTED!!!");

} // END handle_serial_ext_interrupt //

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

bye,

shadowice

the command:

IOWR_ALTERA_AVALON_UART_STATUS(SERIALE_EXT_BASE, (*serial_rcv_exception_ptr & 0xFF7F))

is ignored, the register is not resetted...

why?

shadowice

the only method to flush that bit is to read the UART TX content...

The ISR recalls forever if this operation is not executed

shadowice