ST STM32L0x3 User Manual

RM0367 Rev 7 583/1043
RM0367 General-purpose timers (TIM21/22)
601
22.4 TIM21/22 registers
Refer to Section 1.2 on page 52 for a list of abbreviations used in register descriptions.
The peripheral registers have to be written by half-words (16 bits) or words (32 bits). Read
accesses can be done by bytes (8 bits), half-words (16 bits) or words (32 bits).
22.4.1 TIM21/22 control register 1 (TIMx_CR1)
Address offset: 0x00
Reset value: 0x0000
1514131211109876543210
Res. Res. Res. Res. Res. Res. CKD[1:0] ARPE CMS[1:0] DIR OPM URS UDIS CEN
rw rw rw rw rw rw rw rw rw rw
Bits 15:10 Reserved, must be kept at reset value.
Bits 9:8 CKD: Clock division
This bit-field indicates the division ratio between the timer clock (CK_INT) frequency and
sampling clock used by the digital filters (TIx),
00: t
DTS
= t
CK_INT
01: t
DTS
= 2 × t
CK_INT
10: t
DTS
= 4 × t
CK_INT
11: Reserved
Bit 7 ARPE: Auto-reload preload enable
0: TIMx_ARR register is not buffered.
1: TIMx_ARR register is buffered.
Bits 6:5 CMS[1:0]: Center-aligned mode selection
00: Edge-aligned mode. The counter counts up or down depending on the direction bit
(DIR).
01: Center-aligned mode 1. The counter counts up and down alternatively. Output compare
interrupt flags of channels configured in output (CCxS=00 in TIMx_CCMRx register) are set
only when the counter is counting down.
10: Center-aligned mode 2. The counter counts up and down alternatively. Output compare
interrupt flags of channels configured in output (CCxS=00 in TIMx_CCMRx register) are set
only when the counter is counting up.
11: Center-aligned mode 3. The counter counts up and down alternatively. Output compare
interrupt flags of channels configured in output (CCxS=00 in TIMx_CCMRx register) are set
both when the counter is counting up or down.
Note: It is not allowed to switch from edge-aligned mode to center-aligned mode as long as
the counter is enabled (CEN=1).
Bit 4 DIR: Direction
0: Counter used as upcounter
1: Counter used as downcounter
Bit 3 OPM: One-pulse mode
0: Counter is not stopped on the update event
1: Counter stops counting on the next update event (clearing the CEN bit).

ST STM32L0x3 Specifications

General

Brand	ST
Model	STM32L0x3
Category	Microcontrollers
Language	English