AT91SAM3U4E clock frequency

Kernel
1

disketto wrote on Wednesday, June 12, 2013:

Hello,
i am using the at91Sam3U4E demo board, and the relative FreeRTOS port for IAR Workbench.
I noticed that from the pin of the main clock, i can’t se any wave with my oscilloscope.
I expected to look something like a square wave, but i can see just a continuous signal.
I gave a look at the LowLevelinit() function, that i haven’t changed, and there i found the settings for the clock.
Maybe there is something i have to change to get the signal working ?

Thank you in advance,
Vito Vecchio

2

rtel wrote on Wednesday, June 12, 2013:

Is the problem that the clock is not feeding the MCU, and therefore you cannot run the program, or just that the clock is not visible on an external pin?

Regards.

3

disketto wrote on Wednesday, June 12, 2013:

I have uart  and leds running fine, i was trying to develop a iso7816 driver on usart1, then trying signals with oscilloscope i noticed i did not receive the clock signal, i mean it was a flat signal, so i try to look directly on the pin 24 of the cortex m3 (the clock pin), and it’s always a flat signal. I don’t know if it’s normal or i should see the clock wave.

Thanks in advance,
Vito Vecchio

4

disketto wrote on Wednesday, June 12, 2013:

sorry, to be more detailed, the pin is the PA24

5

rtel wrote on Wednesday, June 12, 2013:

Sorry - that is very chip specific and not FreeRTOS related.  Without looking at your code and getting the chip user guide and data sheet out myself I would have no idea what should be on that pin when.

Regards.

6

disketto wrote on Wednesday, June 12, 2013:

Hello,
i post my functions here, this is my usart1 setting code:

#define USART_MODE_ISO7816_T0  (AT91C_US_USMODE_ISO7816_0 | AT91C_US_CLKS_EXT | AT91C_US_CHRL_8_BITS | AT91C_US_PAR_EVEN | AT91C_US_NBSTOP_2_BIT | AT91C_US_CKLO)

#define BOARD_PIN_USART_RXD        PIN_USART1_RXD
#define BOARD_PIN_USART_TXD        PIN_USART1_TXD
#define BOARD_PIN_USART_CTS        PIN_USART1_CTS
#define BOARD_PIN_USART_RTS        PIN_USART1_RTS
#define BOARD_USART_BASE           AT91C_BASE_US1
#define BOARD_ID_USART             AT91C_ID_US1

#define BOARD_ID_SMART             AT91C_ID_US1

#define PINS_ISO7816_SMART          PIN_USART1_TXD, PIN_USART1_SCK, PIN_ISO7816_RST_SMART, PIN_SMART_CONF_A, PIN_SMART_CONF_B

xComPortHandle xSmartPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
xComPortHandle xReturn = ( ( xComPortHandle ) 2 );
extern void ( vUART_ISR )( void );
const Pin xUSART_Pins = { PINS_ISO7816_SMART };

/* Create the queues used to hold Rx and Tx characters. */
xRxedISOChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
xTxedISOChars = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

/* If the queues were created correctly then setup the serial port
hardware. */
if( ( xRxedISOChars != serINVALID_QUEUE ) && ( xTxedISOChars != serINVALID_QUEUE ) )
{
portENTER_CRITICAL();
{
/* Enable the peripheral clock in the PMC. */
PMC_EnablePeripheral( BOARD_ID_SMART );

/* Configure the USART. */
USART_Configure( BOARD_SMART_BASE, USART_MODE_ISO7816_T0, ulWantedBaud, configCPU_CLOCK_HZ );

/* Configure the interrupt.  Note the pre-emption priority is set
in bits  of the priority value passed as the parameter. */
IRQ_ConfigureIT( BOARD_ID_SMART, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 8 ), USART1_IrqHandler );
IRQ_EnableIT( BOARD_ID_SMART );

/* Configure IO for USART use. */
PIO_Configure( xUSART_Pins, PIO_LISTSIZE( xUSART_Pins ) );

                                   
}
portEXIT_CRITICAL();
}
else
{
xReturn = ( xComPortHandle ) 0;
}

/* This demo file only supports a single port but we have to return
something to comply with the standard demo header file. */
return xReturn;
}

where USART_Configure is:

void USART_Configure(AT91S_USART *usart,
                            unsigned int mode,
                            unsigned int baudrate,
                            unsigned int masterClock)
{
    // Reset and disable receiver & transmitter
    usart->US_CR = AT91C_US_RSTRX | AT91C_US_RSTTX
                   | AT91C_US_RXDIS | AT91C_US_TXDIS;

    // Configure mode
    usart->US_MR = mode;

      usart->US_IDR = -1;
      usart->US_FIDI = 372;
    // Configure baudrate
   // Asynchronous, no oversampling
if(mode==USART_MODE_ISO7816_T0){
        usart->US_BRGR = (masterClock / 3571200);
    }

   USART_SetTransmitterEnabled(usart, 1);
    USART_SetReceiverEnabled(usart, 1);
 
  
     // TODO other modes
}

where i didn’t report the macro, is used the standard value as freeRTOS did.
It could be something missing in the USART_Configure ?

So i expected to find the clock signal on the PA24, since i enabled it with PMC_EnablePeripheal(), but can’t see anything.

Thanks in advance for the reply,
Vito Vecchio