Texas Instruments TMS320DM357 - Manual (Page 20)

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User Case 4: An example of how to do host negotiation to support USB
If the HOSTREQ bit in the DEVCTL register is set, host negotiation is performed by the hardware when
the device enters suspend mode. The bit is cleared when host negotiation is complete.
User Case 5: An example of how to program the USB DMA controller
Example 4. Programming the USB DMA Controller
// Number of DMA channels
#define NUM_CHANNEL 4
// Number of DMA buffers to allocate
#define RX_BUFFERS 32
#define TX_BUFFERS 32
// Memory region to place DMA buffers and descriptors
#define MEMORY_TARGET ".DDREMIF_0_BUF"
// DMA defines
#define SOP
(Uint32) (1<<31)
#define EOP (Uint32) (1<<30)
#define OWNER (Uint32) (1<<29)
#define EOQ (Uint32) (1<<28)
#define ZERO_BYTE (Uint32) (1<<23)
#define RX_ABORT (Uint32) (1<<19)
// DMA channel configuration
#define CH0 0
#define CH1 1
#define CH2 2
#define CH3 3
// Loop variable
int I;
// Variable to keep track of errors
int error = 0;
// Variable to keep track of the number of descriptors built
int tx_desc[NUM_CHANNEL];
// Current TX Buffer descriptor[channel number]
int rx_desc[NUM_CHANNEL]; // Current RX Buffer descriptor[channel number]
// Separate data section for bufferDesc. NOTE: CPPI buffers MUST be aligned to 16-byte
boundaries.
#pragma DATA_SECTION(rx_bufferDesc, MEMORY_TARGET)
Uint32 rx_bufferDesc[NUM_CHANNEL][RX_BUFFERS];
#pragma DATA_SECTION(tx_bufferDesc, MEMORY_TARGET)
Uint32 tx_bufferDesc[NUM_CHANNEL][TX_BUFFERS];
// Initialize CPPI DMA. This code is also included in the controller initialization.
usbRegs->RCPPICR = 0; //Disable the RX DMA
usbRegs->TCPPICR = 0; //Disable the TX DMA
for(I = 0; i<NUM_CHANNEL;i++) { // Initialize CPPI DMA state
usbRegs->CHANNEL[i].TCPPIDMASTATEW0 = 0;
usbRegs->CHANNEL[i].TCPPIDMASTATEW1 = 0;
usbRegs->CHANNEL[i].TCPPIDMASTATEW2 = 0;
usbRegs->CHANNEL[i].TCPPIDMASTATEW3 = 0;
usbRegs->CHANNEL[i].TCPPIDMASTATEW4 = 0;
usbRegs->CHANNEL[i].TCPPIDMASTATEW5 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW0 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW1 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW2 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW3 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW4 = 0;
usbRegs->CHANNEL[i].RCPPIDMASTATEW5 = 0;
20 Universal Serial Bus (USB) Controller SPRUGH3 – November 2008
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