Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK データシート

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SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

If the DMA is not to be used, it is necessary that it be disabled because otherwise it can be enabled by

previous versions of software 

. If this should occur, the DMA can process data before an interrupt

without knowledge of the user. 

The recommended means to disable DMA is as follows:

// Reset IP UDPHS

AT91C_BASE_UDPHS->UDPHS_CTRL &= ~AT91C_UDPHS_EN_UDPHS;

AT91C_BASE_UDPHS->UDPHS_CTRL |= AT91C_UDPHS_EN_UDPHS;

// With OR without DMA !!!

for( i=1; i<=((AT91C_BASE_UDPHS->UDPHS_IPFEATURES &

AT91C_UDPHS_DMA_CHANNEL_NBR)>>4); i++ ) {

// RESET endpoint canal DMA:

// DMA stop channel command

AT91C_BASE_UDPHS->UDPHS_DMA[i].UDPHS_DMACONTROL = 0;

// STOP

command

// Disable endpoint

AT91C_BASE_UDPHS->UDPHS_EPT[i].UDPHS_EPTCTLDIS |= 0XFFFFFFFF;

// Reset endpoint config

AT91C_BASE_UDPHS->UDPHS_EPT[i].UDPHS_EPTCTLCFG = 0;

// Reset DMA channel (Buff count and Control field)

AT91C_BASE_UDPHS->UDPHS_DMA[i].UDPHS_DMACONTROL = 0x02;

// NON

STOP command

// Reset DMA channel 0 (STOP)

AT91C_BASE_UDPHS->UDPHS_DMA[i].UDPHS_DMACONTROL = 0;

// STOP

command

// Clear DMA channel status (read the register for clear it)

AT91C_BASE_UDPHS->UDPHS_DMA[i].UDPHS_DMASTATUS =

AT91C_BASE_UDPHS->UDPHS_DMA[i].UDPHS_DMASTATUS;

}

The setup packet is valid in the DPR while RX_SETUP is set. Once RX_SETUP is cleared by the application, the
UDPHS accepts the next packets sent over the device endpoint.

When a valid setup packet is accepted by the UDPHS:

• the UDPHS device automatically acknowledges the setup packet (sends an ACK response)

• payload data is written in the endpoint

• sets the RX_SETUP interrupt

• the BYTE_COUNT field in the UDPHS_EPTSTAx register is updated

An endpoint interrupt is generated while RX_SETUP in the UDPHS_EPTSTAx register is not cleared. This inter-
rupt is carried out to the microcontroller if interrupts are enabled for this endpoint.

Thus, firmware must detect RX_SETUP polling UDPHS_EPTSTAx or catching an interrupt, read the setup packet
in the FIFO, then clear the RX_SETUP bit in the UDPHS_EPTCLRSTA register to acknowledge the setup stage. 

If STALL_SNT was set to 1, then this bit is automatically reset when a setup token is detected by the device. Then,
the device still accepts the setup stage. (See