STM32W108CBU6 STMICROELECTRONICS [STMicroelectronics], STM32W108CBU6 Datasheet - Page 90

• Manufacturer Part Number: STM32W108CBU6
• Description: High-performance, IEEE 802.15.4 wireless system-on-chip
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

General-purpose timers
Note:
90/179
The capture prescaler is not used for triggering, so it does not need to be configured.
3.
4.
5.
6.
When a rising edge occurs on TI2, the counter counts once and the INT_TIMTIF flag is set.
The delay between the rising edge on TI2 and the actual clock of the counter is due to the
resynchronization circuit on the TI2 input.
Figure 23. Control Circuit in External Clock Mode 1
External clock source mode 2
This mode is selected by writing TIM_ECE = 1 in the TIMx_SMCR register. The counter can
count at each rising or falling edge on the external trigger input ETR.
The TIM_EXTRIGSEL bits in the TIMx_OR register select a clock signal that drives ETR, as
shown in
Table 12.
00
01
10
11
TIM_EXTRIGSEL bits
Select rising edge polarity by writing TIM_CC2P = 0 in the TIMx_CCER register.
Configure the timer in external clock mode 1 by writing TIM_SMS = 111 in the
TIMx_SMCR register.
Select TI2 as the input source by writing TIM_TS = 110 in the TIMx_SMCR register.
Enable the counter by writing TIM_CEN = 1 in the TIMx_CR1 register.
Table
TIM_EXTRIGSEL clock signal selection
12.
PCLK (peripheral clock). When running from the 24 MHz crystal oscillator,
the PCLK frequency is 12 MHz. When the 12M Hz RC oscillator is in use,
the frequency is 6 MHz.
Calibrated 1 kHz internal RC oscillator
Optional 32 kHz clock
TIMxCLK pin. If the TIM_CLKMSKEN bit in the TIMx_OR register is set,
this signal is AND'ed with the TIMxMSK pin providing a gated clock input.
Doc ID 16252 Rev 2
Clock Signal Selection
STM32W108CB, STM32W108HB