7.5.2 MSC_READCTRL - Read Control Register
Offset
Bit Position
0x004
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reset
0
0x1
0
1
0
0
0
Access
R
W
R
WH
R
W
R
W
R
W
R
W
R
W
Name
Bit
Name
Reset
Access Description
31:29
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
28
SCBTP
0
RW
Suppress Conditional Branch Target Perfetch
Enable suppressed Conditional Branch Target Prefetch (SCBTP) function. SCBTP saves energy by delaying Cortex-M con-
ditional branch target prefetches until the conditional branch instruction is in the execute stage. When the instruction rea-
ches this stage, the evaluation of the branch condition is completed and the core does not perform a speculative prefetch of
both the branch target address and the next sequential address. With the SCBTP function enabled, one instruction fetch is
saved for each branch not taken, with a negligible performance penalty.
27:26
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
25:24
MODE
0x1
RWH
Read Mode
After reset, the core clock is 19 MHz from the HFRCO and the MODE field of MSC_READCTRL register is set to WS1. The
reset value is WS1 because the HFRCO may produce a frequency above 19 MHz before it is calibrated. A large wait states
is associated with high frequency. When changing to a higher frequency, this register must be set to a large wait states first
before the core clock is switched to the higher frequency. When changing to a lower frequency, this register should be set
to lower wait states after the frequency transition has been completed. If the HFRCO is used as clock source, wait until the
oscillator is stable on the new frequency to avoid unpredictable behavior.See Flash Wait-States table for the corresponding
threshold for different wait-states.
Value
Mode
Description
0
WS0
Zero wait-states inserted in fetch or read transfers
1
WS1
One wait-state inserted for each fetch or read transfer. See Flash Wait-
States table for details
2
WS2
Two wait-states inserted for eatch fetch or read transfer. See Flash
Wait-States table for details
3
WS3
Three wait-states inserted for eatch fetch or read transfer. See Flash
Wait-States table for details
23:10
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
9
USEHPROT
0
RW
AHB_HPROT Mode
Use ahb_hrpot to determine if the instruction is cacheable or not
8
PREFETCH
1
RW
Prefetch Mode
Set to configure level of prefetching.
7:6
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
Reference Manual
MSC - Memory System Controller
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