Cypress FM4 Series - Descriptor 0 (DES0)

CHAPTER 11: DSTC
572 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
5.13 Descriptor 0 (DES0)
This section explains details of Descriptor 0 (DES0). DES0 sets the basic settings of a transfer.
Descriptor configuration
Address: DESTP + DESP + 0x00
bit
31
30
29
28
27
26
25
24
Field
PCHK[3:0]
Reserved
ACK[1:0]
C attribute
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
D attribute
R
R
R
R
R
R
R
R
bit
23
22
21
20
19
18
17
16
Field
CHLK
DMSET
CHRS[5:0]
C attribute
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
D attribute
R
R
R
R
R
R
R
R
bit
15
14
13
12
11
10
9
8
Field
DAC[1:0]
SAC[2:0]
TW
C attribute
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
D attribute
R
R
R
R
R
R
R
R
bit
7
6
5
4
3
2
1
0
Field
ORL[2:0]
MODE
ST[1:0]
DV[1:0]
C attribute
R/W
R/W
R/W
R/W
R
R
R/W
R/W
D attribute
R
R
R
R
W
W
R/W
R/W
*Symbols for DES area:
The row C attribute in the table above indicates the attribute of the R/W access from the CPU.
The row D attribute in the table above indicates the attribute of the R/W access from the DSTC.
The DES area is built on the memory. As all initial values are indeterminate, they are omitted.
Descriptor function
bit[1:0] DV[1:0] (Descriptor valid)
The DV[1:0] bits specify which of the CPU and the DSTC the ownership of the DES belongs to. The
DV[1:0] bits also specify whether a transfer is executed after the DES open process and whether the DES
close process is to be executed. In the DES close process, the DV[1:0] bits are updated to "00" by the
DSTC.
If DV[1] is set to "1", specific restrictions on reloading the transfer counter and transfer address are added.
If DV[1] is set to "1" and the settings of the DES make the values of DES1, DES2 and DES3 not return to
their respective values, the DSTC notifies of the CPU a DES open error.
Value
Function
00
The owner is the CPU. No transfer is executed. No DES close process is executed.
( If the DSTC read this value, the DSTC notifies a DES open error.)
01
The owner is the DSTC. A transfer is executed. The DES close process is executed.
10
The owner is the DSTC. No transfer is executed. The DES close process is executed.
11
The owner is the DSTC. A transfer is executed. No DES close process is executed.