Data Structures

group group_dma_data_structures
struct DW_Type
#include <ip_type.h>

struct cy_stc_dma_descriptor_t
#include <cy_dma.h>

DMA descriptor structure type.

It is a user/component-declared structure allocated in RAM. The DMA HW requires a pointer to this structure to work with it.

For advanced users: the descriptor can be allocated even in flash, then the user manually predefines all the structure items with constants. This is because most of the driver’s API (especially functions modifying descriptors, including Cy_DMA_Descriptor_Init()) can’t work with read-only descriptors.

Public Members

uint32_t ctl

0x00000000 Descriptor control

uint32_t src

0x00000004 Descriptor source

uint32_t dst

0x00000008 Descriptor destination

uint32_t xCtl

0x0000000C Descriptor X loop control

uint32_t yCtl

0x00000010 Descriptor Y loop control

uint32_t nextPtr

0x00000014 Descriptor next pointer

struct cy_stc_dma_descriptor_config_t
#include <cy_dma.h>

This structure is a configuration structure pre-initialized by the user and passed as a parameter to the Cy_DMA_Descriptor_Init().

It can be allocated in RAM/flash (the user’s choice). In case of flash allocation, there is a possibility to reinitialize the descriptor in runtime. This structure has all the parameters of the descriptor as separate parameters. Most of these parameters are represented in the cy_stc_dma_descriptor_t structure as bitfields.

Public Members

cy_en_dma_retrigger_t retrigger

Specifies whether the DW controller should wait for the input trigger to be deactivated.

cy_en_dma_trigger_type_t interruptType

Sets the event that triggers an interrupt.

See cy_en_dma_trigger_type_t.

cy_en_dma_trigger_type_t triggerOutType

Sets the event that triggers an output.

See cy_en_dma_trigger_type_t.

cy_en_dma_channel_state_t channelState

Specifies whether the channel is enabled or disabled on completion of descriptor.

See cy_en_dma_channel_state_t.

cy_en_dma_trigger_type_t triggerInType

Sets what type of transfer is triggered.

See cy_en_dma_trigger_type_t.

cy_en_dma_data_size_t dataSize

The size of the data bus for transfer.

See cy_en_dma_data_size_t.

cy_en_dma_transfer_size_t srcTransferSize

The source transfer size.

cy_en_dma_transfer_size_t dstTransferSize

The destination transfer size.

cy_en_dma_descriptor_type_t descriptorType

The type of the descriptor.

See cy_en_dma_descriptor_type_t.

void *srcAddress

The source address of the transfer.

void *dstAddress

The destination address of the transfer.

For CPUSS_ver2 only: for CRC transfer, the CRC result without post-processing (reversing and/or XORing, if used) is placed into the dstAddress.

int32_t srcXincrement

The address increment of the source after each X-loop transfer.

Valid range is -2048 … 2047.

int32_t dstXincrement

The address increment of the destination after each X-loop transfer.

Valid range is -2048 … 2047.

uint32_t xCount

The number of transfers in an X-loop.

Valid range is 1 … 256.

int32_t srcYincrement

The address increment of the source after each Y-loop transfer.

Valid range is -2048 … 2047.

int32_t dstYincrement

The address increment of the destination after each Y-loop transfer.

Valid range is -2048 … 2047.

uint32_t yCount

The number of X-loops in the Y-loop.

Valid range is 1 … 256.

cy_stc_dma_descriptor_t *nextDescriptor

The next descriptor to chain after completion.

A NULL value will signify no chaining.

struct cy_stc_dma_channel_config_t
#include <cy_dma.h>

This structure holds the initialization values for the DMA channel.

Public Members

cy_stc_dma_descriptor_t *descriptor

The DMA descriptor associated with the channel being initialized.

bool preemptable

Specifies whether the channel is preemptable by another higher-priority channel.

uint32_t priority

This parameter specifies the channel’s priority.

bool enable

This parameter specifies whether the channel is enabled after initializing.

bool bufferable

This parameter specifies whether a write transaction can complete.

without waiting for the destination to accept the write transaction data.

struct cy_stc_dma_crc_config_t
#include <cy_dma.h>

This structure holds the initialization values for the CRC feature, only for CPUSS_ver2.

Public Members

bool dataReverse

Specifies the bit order in which a data byte is processed (reversal is performed after XORing): ‘false’: Most significant bit (bit 1) first.

‘true’: Least significant bit (bit 0) first.

uint32_t dataXor

Specifies a byte mask with which each data byte is XORed.

The XOR is performed before data reversal.

bool reminderReverse

Specifies whether the remainder is bit reversed (reversal is performed after XORing).

Note: this parameter doesn’t affect the CRC value stored into the dstAddress. The reversed value remains in the CRC_REM_RESULT register.

uint32_t reminderXor

Specifies a mask with which the remainder is XORed.

The XOR is performed before remainder reversal. Note: this parameter doesn’t affect the CRC value stored into the dstAddress. The XORed value remains in the CRC_REM_RESULT register.

uint32_t polynomial

CRC polynomial.

The polynomial is represented WITHOUT the high order bit (this bit is always assumed ‘1’). The polynomial should be aligned/shifted such that the more significant bits (bit 31 and down) contain the polynomial and the less significant bits (bit 0 and up) contain padding ‘0’s. Some frequently used polynomials:

  • CRC32: POLYNOMIAL is 0x04c11db7 (x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1).

  • CRC16: POLYNOMIAL is 0x80050000 (x^16 + x^15 + x^2 + 1, shifted by 16 bit positions).

  • CRC16 CCITT: POLYNOMIAL is 0x10210000 (x^16 + x^12 + x^5 + 1, shifted by 16 bit positions).

uint32_t lfsrInitVal

The initial value of the Linear Feedback Shift Register.