Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Hoja De Datos

 1340

SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

– c- Restart the UTMIPLL and wait for the PLL Lock bit

Warning: When booting out of the internal ROM, this workaround is not implemented and therefore SAMBA will not
be functional.

Below is a possible implementation of the workaround:

/* First enable the UTMI PLL */

AT91C_BASE_PMC->CKGR_UCKR |= (AT91C_CKGR_UCKR_PLLCOUNT & (0x3 << 20)) |

AT91C_CKGR_UCKR_UPLLEN;

tmp =0;

while (((AT91C_BASE_PMC->PMC_SR & AT91C_PMC_SR_LOCKU) == 0) && (tmp++ < DELAY));

/* Disable the PLLUTMI and wait 10µs min*/

AT91C_BASE_PMC->CKGR_UCKR &= ~AT91C_CKGR_UCKR_UPLLEN;

tmp = 0;

while(tmp++ < DELAY2); // DELAY2 must be defined to fit the 10µs min;

/* Re- enable the UTMI PLL and wait for the PLL lock status*/

AT91C_BASE_PMC->CKGR_UCKR |= (AT91C_CKGR_UCKR_PLLCOUNT & (0x3 << 20)) |

AT91C_CKGR_UCKR_UPLLEN;

tmp =0;

while (((AT91C_BASE_PMC->PMC_SR & AT91C_PMC_SR_LOCKU) == 0) && (tmp++ < DELAY));

The DLL used to oversample the incoming bitstream may not lock in the correct phase, leading to a bad reception
of the incoming packets.

This issue may occur after the USB device resumes from the Suspend mode.

The DLL is used only in the High Speed mode, meaning the Full Speed mode is not impacted by this issue.

This issue may occur on the USB device after a reset leading to a SAM-BA connection issue.

To prevent a SAM-BA execution issue, the USB device must be connected via a USB Full Speed hub to the PC.

At application level, the DLL can be re-initialized in the correct state by toggling the BIASEN bit (high -> low ->
high) when resuming from the Suspend mode. 

The BIASEN bit is located in the CKGR_UCKR register in the PMC user interface.

The function below can be used to generate the pulse on the bias signal.

void generate_pulse_bias(void)

{

unsigned int * pckgr_uckr = (unsigned int *) 0xFFFFFC1C;

* pckgr_uckr &= ~AT91_PMC_BIASEN;

* pckgr_uckr |= AT91_PMC_BIASEN;

}

In the USB device driver, the generate_pulse_bias function must be implemented in the “USB end of reset” and
“USB end of resume” interrupts.