Information

37.3.4 Low Power Timer Counter Register (LPTMRx_CNR)
Addresses: LPTMR0_CNR is 4004_0000h base + Ch offset = 4004_000Ch
Bit 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
R
0 COUNTER
W
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
LPTMRx_CNR field descriptions
Field Description
31–16
Reserved
This read-only field is reserved and always has the value zero.
15–0
COUNTER
Counter Value
37.4 Functional description
37.4.1 LPTMR power and reset
The LPTMR remains powered in all power modes, including low-leakage modes. If the
LPTMR is not required to remain operating during a low-power mode, then it must be
disabled before entering the mode.
The LPTMR is reset only on global Power On Reset (POR) or Low Voltage Detect
(LVD). When configuring the LPTMR registers, the CSR must be initially written with
the timer disabled, before configuring the PSR and CMR. Then, CSR[TIE] must be set as
the last step in the initialization. This ensures the LPTMR is configured correctly and the
LPTMR counter is reset to zero following a warm reset.
37.4.2 LPTMR clocking
The LPTMR prescaler/glitch filter can be clocked by one of the four clocks. The clock
source must be enabled before the LPTMR is enabled.
NOTE
The clock source selected may need to be configured to remain
enabled in low-power modes, otherwise the LPTMR will not
operate during low-power modes.
Chapter 37 Low-Power Timer (LPTMR)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 835