hello_world_small Uart input

I realize that this post is old and you probably already found a solution but here you go anyway:

# include "altera_avalon_uart_regs.h"

char ch;

ch = IORD_ALTERA_AVALON_UART_RXDATA(UART1_BASE);

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originally posted by jakobjones@Feb 15 2007, 10:00 PM

i realize that this post is old and you probably already found a solution but here you go anyway:

# include "altera_avalon_uart_regs.h"

char ch;

ch = iord_altera_avalon_uart_rxdata(uart1_base);

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=21653)

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What if you are polling for a UART character? That command will just dump whatever&#39;s in the register, regardless of whether there&#39;s something there. I tried using this before reading the post, and I just get into a massive loop because there is no event that the code waits for.

I believe that you need to look at RRDY in the _STATUS register (bit mask 0x0080) to see if there&#39;s a byte there. I have been trying this, but I&#39;m getting "blank" data back. I believe that it&#39;s because I&#39;m also using printf() HAL functions, which the datasheet refers to there being a problem running both register access and HAL at the same time.

I&#39;m having issues with a "small" build, and the getchar() and file i/o methods seem to work fine, but don&#39;t compile properly when targeting a device that does not have enough room to cram a "full" C library (EP2S15).

Does anyone have a solution for polling for a UART character w/out getchar() or getc()?

I suspect that I could stop using fprint() - HAL, and do all of the character I/O using IOWR_ALTERA_AVALON_UART_TXDATA(UART_0_BASE, data) commands, but rewriting fprint() is not too appealing, since I&#39;m a hardware/FPGA guy that&#39;s dabbling in C.

Any thoughts/comments on this would be appreciated.

Thanks,

Jeff

with fprintf:

fprintf(FILE, "%d\r\n", var);

instead do this:

char buffer[1000];

int count;

sprintf(buffer, "%d\r\n", var);

for(count = 0; buffer[count]; ++count)

{

IOWR_ALTERA_AVALON_UART_TXDATA(UART_0_BASE, buffer[count]);

}

This is quick and dirty. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/unsure.gif

Missing is buffer overrun check but it will basicly work.

Karsten

In case this helps anyone else out, I did end up getting my project to fit inside of a 10kB block, as opposed to the 52kB or so that it was bloating into previously. Here are a few of the steps that I followed:

1. I ended up building a new Nios project using the "memory test" template (instead of the "blank" template). This was per a suggestion by an Altera FAE that maybe the blank template would instantiate (and compile) all possible code that could be used (as opposed to just what would be needed for a UART-based memory test program), thus increasing the size. I can&#39;t say w/ any certainty whether or not this actually effected the size or not.

2. I replaced all references to printf() and getchar() with alt_printf() and alt_getchar(). The catch here being that these are light-weight versions of the bona-fide C function calls, and I had to make modifications to my code to account for this. The alt_printf() only has a few variable substitutions that can be made (most of my changes had to do with this), while I did not have to make any modifications to alt_getchar().

So those where the two major changes that I made, which then allowed me to check "lightweight device driver API", and giving me the small footprint. Now that I look back at the project settings, it did not require me to select "small C library" in order to get the reduced size.

The SOPC project used the following peripherals:

cpu_0 (Nios II/e w/ level 1 debug)

onchip_memory (16k)

uart_0

various parallel I/O (pio)

Hope this helps anyone else that might be having the same problem.

Jeff