MCBSTM32EXL Keil, MCBSTM32EXL Datasheet - Page 350

• Manufacturer Part Number: MCBSTM32EXL
• Description: BOARD EVALUATION FOR STM32F103ZE
• Manufacturer: Keil

Specifications of MCBSTM32EXL

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

General-purpose timer (TIMx)
Note:
Note:
350/995
Using one timer as prescaler for the another
Figure 139. Master/Slave timer example
For example, you can configure Timer 1 to act as a prescaler for Timer 2. Refer to
Figure
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If OCx is selected on Timer 1 as trigger output (MMS=1xx), its rising edge is used to clock
the counter of timer 2.
Using one timer to enable another timer
In this example, we control the enable of Timer 2 with the output compare 1 of Timer 1.
Refer to
OC1REF of Timer 1 is high. Both counter clock frequencies are divided by 3 by the
prescaler compared to CK_INT (f
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The counter 2 clock is not synchronized with counter 1, this mode only affects the Timer 2
counter enable signal.
Configure Timer 1 in master mode so that it outputs a periodic trigger signal on each
update event UEV. If you write MMS=010 in the TIM1_CR2 register, a rising edge is
output on TRGO1 each time an update event is generated.
To connect the TRGO1 output of Timer 1 to Timer 2, Timer 2 must be configured in
slave mode using ITR1 as internal trigger. You select this through the TS bits in the
TIM2_SMCR register (writing TS=000).
Then you put the slave mode controller in external clock mode 1 (write SMS=111 in the
TIM2_SMCR register). This causes Timer 2 to be clocked by the rising edge of the
periodic Timer 1 trigger signal (which correspond to the timer 1 counter overflow).
Finally both timers must be enabled by setting their respective CEN bits (TIMx_CR1
register).
Configure Timer 1 master mode to send its Output Compare 1 Reference (OC1REF)
signal as trigger output (MMS=100 in the TIM1_CR2 register).
Configure the Timer 1 OC1REF waveform (TIM1_CCMR1 register).
Configure Timer 2 to get the input trigger from Timer 1 (TS=000 in the TIM2_SMCR
register).
Configure Timer 2 in gated mode (SMS=101 in TIM2_SMCR register).
Enable Timer 2 by writing ‘1’ in the CEN bit (TIM2_CR1 register).
Start Timer 1 by writing ‘1’ in the CEN bit (TIM1_CR1 register).
139. To do this:
Figure 139
Clock
Prescaler
for connections. Timer 2 counts on the divided internal clock only when
Counter
TIMER 1
UEV
Doc ID 13902 Rev 9
CK_CNT
Master
control
mode
MMS
= f
TRGO1
CK_INT
ITR1
selection
/3).
trigger
Input
TS
control
Slave
mode
SMS
CK_PSC
TIMER 2
Prescaler
Counter
RM0008