[ECOS] A problem about UART output (Redboot porting for Versatile/ARM926EJ-S)

[ECOS] A problem about UART output (Redboot porting for Versatile/ARM926EJ-S)

[Tim Yin]

Hi All,

	I'am porting eCos/RedBoot to Versatile/ARM926EJ-S with Integrator/ARM966E as baseline. Thanks to this Saturday. It's the first time my HyperTerminal got characters came from RedBoot. They were showed belowing. 

	RedBoot(tm)
		
    Only 12 characters! I debug it and found that it got into a loop in hal_diag.c:cyg_hal_plf_serial_putc().
 
	After transmit the first 12 characters, the value of AMBA_UARTFR register changed from 0x18 to 0x38.
So it cann't get out of the loop.
	
	The Release version of UART is PL011 r1p3. The flowing is the relevant code. 

--------------------------------------------------------
	#define AMBA_UARTFR_TXFF                0x20
	#define AMBA_UARTFR_RXFE                0x10
	#define AMBA_UARTFR_BUSY                0x08

	// AMBA uart access macros
	#define GET_STATUS(p)		(IO_READ((p) + AMBA_UARTFR))
	#define TX_READY(s)		(((s) & AMBA_UARTFR_TXFF) == 0)

	void
	cyg_hal_plf_serial_putc(void *__ch_data, char c)
	{
    	...

    	do {
      	status = GET_STATUS(base);
    	} while (!TX_READY(status));	// wait until ready
    
		PUT_CHAR(base, c);
		...
	}
--------------------------------------------------------

 	Any help about this?
	
Best regards,
Tim 　　　　
　　　　　　　　

RE: [ECOS] A problem about UART output (Redboot porting for Versatile/ARM926EJ-S)

[Paul D. DeRocco]

> From: Tim Yin
>
>       I'am porting eCos/RedBoot to Versatile/ARM926EJ-S with
> Integrator/ARM966E as baseline. Thanks to this Saturday. It's the
> first time my HyperTerminal got characters came from RedBoot.
> They were showed belowing.
>
>       RedBoot(tm)
>              
>     Only 12 characters! I debug it and found that it got into a
> loop in hal_diag.c:cyg_hal_plf_serial_putc().
> 
>       After transmit the first 12 characters, the value of
> AMBA_UARTFR register changed from 0x18 to 0x38.
> So it cann't get out of the loop.
>      
>       The Release version of UART is PL011 r1p3. The flowing is
> the relevant code.
>
> --------------------------------------------------------
>       #define AMBA_UARTFR_TXFF                0x20
>       #define AMBA_UARTFR_RXFE                0x10
>       #define AMBA_UARTFR_BUSY                0x08
>
>       // AMBA uart access macros
>       #define GET_STATUS(p)           (IO_READ((p) + AMBA_UARTFR))
>       #define TX_READY(s)             (((s) & AMBA_UARTFR_TXFF) == 0)
>
>       void
>       cyg_hal_plf_serial_putc(void *__ch_data, char c)
>       {
>       ...
>
>       do {
>               status = GET_STATUS(base);
>       } while (!TX_READY(status));    // wait until ready
>    
>               PUT_CHAR(base, c);
>               ...
>       }
> --------------------------------------------------------
>
>       Any help about this?

Suspicions:

1. Something is stopping the clock.

2. Hardware flow control is enabled, but the CTS input is floating.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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