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Functional Description
11.3.3.2.4 Count for 1st Dimension (ACNT)
ACNT represents the number of bytes within the 1st dimension of a transfer. ACNT is a 16-bit unsigned
value with valid values between 0 and 65 535. Therefore, the maximum number of bytes in an array is
65 535 bytes (64K – 1 bytes). ACNT must be greater than or equal to 1 for a TR to be submitted to
EDMA3TC. A transfer with ACNT equal to 0 is considered either a null or dummy transfer. A dummy or
null transfer generates a completion code depending on the settings of the completion bit fields in OPT.
See Section 11.3.3.5 and Section 11.3.5.3 for details on dummy/null completion conditions.
11.3.3.2.5 Count for 2nd Dimension (BCNT)
BCNT is a 16-bit unsigned value that specifies the number of arrays of length ACNT. For normal
operation, valid values for BCNT are between 1 and 65 535. Therefore, the maximum number of arrays in
a frame is 65 535 (64K – 1 arrays). A transfer with BCNT equal to 0 is considered either a null or dummy
transfer. A dummy or null transfer generates a completion code depending on the settings of the
completion bit fields in OPT.
See Section 11.3.3.5 and Section 11.3.5.3 for details on dummy/null completion conditions.
11.3.3.2.6 Count for 3rd Dimension (CCNT)
CCNT is a 16-bit unsigned value that specifies the number of frames in a block. Valid values for CCNT are
between 1 and 65 535. Therefore, the maximum number of frames in a block is 65 535 (64K – 1 frames).
A transfer with CCNT equal to 0 is considered either a null or dummy transfer. A dummy or null transfer
generates a completion code depending on the settings of the completion bit fields in OPT.
A CCNT value of 0 is considered either a null or dummy transfer. See Section 11.3.3.5 and
Section 11.3.5.3 for details on dummy/null completion conditions.
11.3.3.2.7 BCNT Reload (BCNTRLD)
BCNTRLD is a 16-bit unsigned value used to reload the BCNT field once the last array in the
2nd dimension is transferred. This field is only used for A-synchronized transfers. In this case, the
EDMA3CC decrements the BCNT value by 1 on each TR submission. When BCNT reaches 0, the
EDMA3CC decrements CCNT and uses the BCNTRLD value to reinitialize the BCNT value.
For AB-synchronized transfers, the EDMA3CC submits the BCNT in the TR and the EDMA3TC
decrements BCNT appropriately. For AB-synchronized transfers, BCNTRLD is not used.
11.3.3.2.8 Source B Index (SRCBIDX)
SRCBIDX is a 16-bit signed value (2s complement) used for source address modification between each
array in the 2nd dimension. Valid values for SRCBIDX are between –32 768 and 32 767. It provides a
byte address offset from the beginning of the source array to the beginning of the next source array. It
applies to both A-synchronized and AB-synchronized transfers. Some examples:
• SRCBIDX = 0000h (0): no address offset from the beginning of an array to the beginning of the next
array. All arrays are fixed to the same beginning address.
• SRCBIDX = 0003h (+3): the address offset from the beginning of an array to the beginning of the next
array in a frame is 3 bytes. For example, if the current array begins at address 1000h, the next array
begins at 1003h.
• SRCBIDX = FFFFh (–1): the address offset from the beginning of an array to the beginning of the next
array in a frame is –1 byte. For example, if the current array begins at address 5054h, the next array
begins at 5053h.
11.3.3.2.9 Destination B Index (DSTBIDX)
DSTBIDX is a 16-bit signed value (2s complement) used for destination address modification between
each array in the 2nd dimension. Valid values for DSTBIDX are between –32 768 and 32 767. It provides
a byte address offset from the beginning of the destination array to the beginning of the next destination
array within the current frame. It applies to both A-synchronized and AB-synchronized transfers. See
SRCBIDX for examples.
887
SPRUH73H–October 2011–Revised April 2013 Enhanced Direct Memory Access (EDMA)
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