208
32059L–AVR32–01/2012
AT32UC3B
18.8.2
Mode Register
Name:
MR
Access Type:
Read/Write
Offset:
0x04
Reset Value:
0x00000000
DLYBCS: Delay Between Chip Selects
This field defines the delay from NPCS inactive to the activation of another NPCS. The DLYBCS time guarantees non-
overlapping chip selects and solves bus contentions in case of peripherals having long data float times.
If DLYBCS is less than or equal to six, six CLK_SPI periods will be inserted by default.
Otherwise, the following equation determines the delay:
PCS: Peripheral Chip Select
This field is only used if Fixed Peripheral Select is active (PS = 0).
If PCSDEC = 0:
PCS = xxx0NPCS[3:0] = 1110
PCS = xx01NPCS[3:0] = 1101
PCS = x011NPCS[3:0] = 1011
PCS = 0111NPCS[3:0] = 0111
PCS = 1111forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC = 1:
NPCS[3:0] output signals = PCS.
LLB: Local Loopback Enable
0: Local loopback path disabled.
1: Local loopback path enabled (
LLB controls the local loopback on the data serializer for testing in Master Mode only. (MISO is internally connected on MOSI.)
MODFDIS: Mode Fault Detection
0: Mode fault detection is enabled.
1: Mode fault detection is disabled.
PCSDEC: Chip Select Decode
0: The chip selects are directly connected to a peripheral device.
1: The four chip select lines are connected to a 4- to 16-bit decoder.
When PCSDEC equals one, up to 15 Chip Select signals can be generated with the four lines using an external 4- to 16-bit
decoder. The Chip Select Registers define the characteristics of the 15 chip selects according to the following rules:
CSR0 defines peripheral chip select signals 0 to 3.
CSR2 defines peripheral chip select signals 8 to 11.
31
30
29
28
27
26
25
24
DLYBCS
23
22
21
20
19
18
17
16
––––
PCS
15
14
13
12
11
10
9
8
––––––––
76
543210
LLB
-
MODFDIS
–
PCSDEC
PS
MSTR
Delay Between Chip Selects
DLYBCS
CLKSPI
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