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GPTM Registers
1312
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
General-Purpose Timers
18.5.28 GPTMCC Register (Offset = 0xFC8) [reset = 0x0]
GPTM Clock Configuration (GPTMCC)
The GPTMCC register controls the clock source for the General-Purpose Timer module.
NOTE:
When the ALTCLK bit is set in the GPTMCC register to enable using the alternate clock
source, the synchronization imposes restrictions on the starting count value (down-count),
terminal value (up-count) and the match value. This restriction applies to all modes of
operation. Each event must be spaced by 4 Timer (ALTCLK) clock p 2 system clock
periods. If some events do not meet this requirement, then it is possible that the timer block
may need to be reset for correct functionality to be restored.
Example: ALTCLK= T
PIOSC
= 62.5 ns (16 MHz trimmed)
T
hclk
= 1 µs (1 MHz)
4 × 62.5 ns + 2 × 1 µs = 2.25 µs 2.25 µs / 62.5 ns = 36 (or 0x23)
The minimum values for the periodic or one-shot with a match interrupt enabled are:
GPTMTAMATCHR = 0x23 GPTMTAILR = 0x46
GPTMCC is shown in
and described in
.
Return to
Figure 18-36. GPTMCC Register
31
30
29
28
27
26
25
24
RESERVED
R-0x0
23
22
21
20
19
18
17
16
RESERVED
R-0x0
15
14
13
12
11
10
9
8
RESERVED
R-0x0
7
6
5
4
3
2
1
0
RESERVED
ALTCLK
R-0x0
R/W-0x0
Table 18-39. GPTMCC Register Field Descriptions
Bit
Field
Type
Reset
Description
31-1
RESERVED
R
0x0
0
ALTCLK
R/W
0x0
Alternate Clock Source
0x0 = System clock (based on clock source and divisor factor
programmed in RSCLKCFG register in the System Control Module)
0x1 = Alternate clock source as defined by ALTCLKCFG register in
System Control Module.