...the world's most energy friendly microcontrollers
2014-07-02 - Gecko Family - d0001_Rev1.30
36
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Bit
Name
Reset
Access
Description
31:3
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
2:0
MODE
0x1
RW
Read Mode
If software wants to set a core clock frequency above 16 MHz, this register must be set to WS1 or WS1SCBTP before the core
clock is switched to the higher frequency. When changing to a lower frequency, this register can be set to WS0 or WS0SCBTP
after the frequency transition has been completed. After reset, the core clock is 14 MHz from the HFRCO but the MODE field of
MSC_READCTRL register is set to WS1. This is because the HFRCO may produce a frequency above 16 MHz before it is calibrated.
If the HFRCO is used as clock source, wait until the oscillator is stable on the new frequency to avoid unpredictable behavior.
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. This mode is required for a core
frequency above 16 MHz.
2
WS0SCBTP
Zero wait-states inserted with the Suppressed Conditional Branch Target Prefetch
(SCBTP) function enabled. SCBTP saves energy by delaying the Cortex' conditional
branch target prefetches until the conditional branch instruction is in the execute stage.
When the instruction reaches 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.
3
WS1SCBTP
One wait-state access with SCBTP enabled.
7.5.3 MSC_WRITECTRL - Write Control Register
Offset
Bit Position
0x008
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
0
Access
RW
RW
Name
Bit
Name
Reset
Access
Description
31:2
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
1
IRQERASEABORT
0
RW
Abort Page Erase on Interrupt
When this bit is set to 1, any Cortex interrupt aborts any current page erase operation. Executing that interrupt vector from Flash
will halt the CPU.
0
WREN
0
RW
Enable Write/Erase Controller
When this bit is set, the MSC write and erase functionality is enabled.
7.5.4 MSC_WRITECMD - Write Command Register
Offset
Bit Position
0x00C
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
0
0
0
0
Access
W1
W1
W1
W1
W1
Name
Summary of Contents for EFM32G
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