STM32W108CB STMicroelectronics, STM32W108CB Datasheet - Page 127

• Manufacturer Part Number: STM32W108CB
• Description: High-performance, IEEE 802.15.4 wireless system-on-chip with embedded Flash memory
• Manufacturer: STMicroelectronics

Specifications of STM32W108CB

• Receive Current (w/ Cpu): 27 mA
• Transmit Current (w/ Cpu, +3 Dbm Tx): 31 mA
• Low Deep Sleep Current, With Retained Ram And Gpio: 400 nA/800 nA with/without sleep timer
• Standard Arm Debug Capabilities: Flash patch & breakpoint; data watchpoint & trace; instrumentation trace macrocell
• Single Voltage Operation: 2.1-3.6 V with internal 1.8 V and 1.25 V regulators

STM32W108HB STM32W108CC STM32W108CB STM32W108CZ
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 85.
Figure 29
Figure 29. External trigger input block
For example, to configure the up-counter to count each 2 rising edges on ETR, use the
following procedure:
●
●
●
●
●
The counter counts once each 2 ETR rising edges.
The delay between the rising edge on ETR and the actual clock of the counter is due to the
resynchronization circuit on the ETRP signal.
00
01
10
11
TIM_EXTRIGSEL bits
As no filter is needed in this example, write TIM_ETF = 0000 in the TIMx_SMCR
register.
Set the prescaler by writing TIM_ETPS = 01 in the TIMx_SMCR register.
Select rising edge detection on ETR by writing TIM_ETP = 0 in the TIMx_SMCR
register.
Enable external clock mode 2 by writing TIM_ECE = 1 in the TIMx_SMCR register.
Enable the counter by writing TIM_CEN = 1 in the TIMx_CR1 register.
Table
gives an overview of the external trigger input block.
TIM_EXTRIGSEL clock signal selection
85.
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 13
Clock signal selection
General-purpose timers
127/232