EM35X-DEV-IAR Ember, EM35X-DEV-IAR Datasheet - Page 135

• Manufacturer Part Number: EM35X-DEV-IAR
• Description: KIT DEV EM35X IAR EWARM ZIGBEE
• Manufacturer: Ember
• Series: EM35xr
• Type: Zigbeer

Specifications of EM35X-DEV-IAR

• Frequency: 2.4GHz
• For Use With/related Products: EM351, EM357
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 636-1027

Figure 9-15 gives an overview of the 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.
Figure 9-16 illustrates counting every 2 rising edges of ETR using external clock mode 2.
TIM_EXTRIGSEL bits Clock Signal Selection
As no filter is needed in this example, write TIM_ETF = 0000 in the TIMx_SMCR register.
Set the prescaler: Write TIM_ETPS = 01 in the TIMx_SMCR register.
Select rising edge detection on ETR: WriteTIM_ETP = 0 in the TIMx_SMCR register.
Enable external clock mode 2: Write TIM_ECE = 1 in the TIMx_SMCR register.
Enable the counter: Write TIM_CEN = 1 in the TIMx_CR1 register.
00
01
10
11
PCLK (peripheral clock). When running from the 24 MHz crystal oscillator, the PCLK
TIMxCLK pin. If the TIM_CLKMSKEN bit in the TIMx_OR register is set, this signal is
frequency is 12 MHz. When the 12 MHz RC oscillator is in use, the frequency is 6 MHz.
Calibrated 1 kHz internal RC oscillator
Optional 32.786 kHz clock
AND’ed with the TIMxMSK pin providing a gated clock input.
Table 9-2. TIM_EXTRIGSEL Clock Signal Selection
Figure 9-15. External Trigger Input Block
Final
9-11
EM351 / EM357
120-035X-000G