Rainbow Electronics AT91CAP9S250A - Manual (Page 855)

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6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
44.4.7 Transfer Without DMA
Important. If the DMA is not to be used, it is neccessary that it be disabled because otherwise it
can be enabled by previous versions of software without warning. If this should occur, the DMA
can process data before an interrupt without knowlege 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;
}
44.4.8 Handling Transactions with USB V2.0 Device Peripheral
44.4.8.1 Setup Transaction
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 interrupt is carried out to the microcontroller if interrupts are enabled for this
endpoint.