[En-Nut-Discussion] Problem with stdin on DBGU

[Bernd Walter]

On Fri, Jun 04, 2010 at 06:43:54PM +0200, Bernd Walter wrote:
> Controller is AT91SAM7S321
> Nut/OS is 4.9.8.
> 
> My main function starts with:
>         // Initialize the console
>         uint32_t cons_baud = 115200;
>         NutRegisterDevice(&DEV_CONS, 0, 0);
>         freopen(DEV_CONS_NAME, "w", stdout);
>         if (freopen(DEV_CONS_NAME, "w", stderr) == NULL) {
>                 printf("open stderr failed\n");
>         }
>         if (freopen(DEV_CONS_NAME, "r", stdin) == NULL) {
>                 printf("open stdin failed\n");
>         }
>         _ioctl(_fileno(stdin), UART_SETSPEED, &cons_baud);
> 
> With:
> #define DEV_CONS        devDebug
> #define DEV_CONS_NAME   "dbgu"
> 
> Then after many successfull printf I have the following code:
>         for(;;) {
>                 char *cp;
>                 static char buf[128];
>                 buf[0] = '\0';
>                 printf("ready!\n");
>                 fflush(stdout);
>                 NutThreadYield();
>                 if (fgets(buf, sizeof(buf), stdin) == 0) {
>                         printf("<EOF>\n");
>                         fflush(stdout);
>                         NutThreadYield();
>                         continue;
>                 }
>                 printf("<got something>\n");
>                 fflush(stdout);
>                 NutThreadYield();
>                 if ((cp = strchr(buf, '\r')) != 0) {
>                         *cp = 0;
>                 }
>                 if ((cp = strchr(buf, '\n')) != 0) {
>                         *cp = 0;
>                 }
>                 if (buf[0] == 0) {
>                         continue;
>                 }
> 
>                 if (strncmp(buf, "memory", strlen(buf)) == 0) {
>                         printf("%u bytes RAM free\r\n", (u_int)NutHeapAvailable());
>                         continue;
>                 }
> 
>                 printf("List of commands follows\n");
>                 printf("memory\tQueries number of RAM bytes free\n");
>         }
> 
> With fgets the system just restarts.
> I've debugged it up to _read and it turned out that dev->dev_read is
> NULL.
> Not surprising that calling code at address 0 restarts the system.

Oh - I've just notice in debug_at91.c that there really is no read
function.
That's very unexpected for me :-(
Is there any special reason for this?
I know that is hasn't some of the very special features that USART
have and that it shares an interrupt, but otherwise it is very similar
to USART.
The reason I want to use this interface is that I already have a
usecase for the USART and that the DBGU is already wired for flashing
via SAM-BA.

I also noticed devDbguAt91 - ist useable?
There is a #define NUT_DEPRECATED at start - sounds not.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.