
DocID024597 Rev 5
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RM0351
Digital-to-analog converter (DAC)
647
Figure 140. Timing diagram for conversion with trigger disabled TEN = 0
19.3.5 DAC
output
voltage
Digital inputs are converted to output voltages on a linear conversion between 0 and V
REF+
.
The analog output voltages on each DAC channel pin are determined by the following
equation:
19.3.6 DAC
trigger
selection
If the TENx control bit is set, conversion can then be triggered by an external event (timer
counter, external interrupt line). The TSELx[2:0] control bits determine which out of 8 possi-
ble events will trigger conversion as shown in bits TSEL1[2:0] and TSEL2[2:0] in
Section 19.5.1: DAC control register (DAC_CR)
Each time a DAC interface detects a rising edge on the selected trigger source (refer to the
table below), the last data stored into the DAC_DHRx register are transferred into the
DAC_DORx register. The DAC_DORx register is updated three APB1 cycles after the
trigger occurs.
If the software trigger is selected, the conversion starts once the SWTRIG bit is set.
SWTRIG is reset by hardware once the DAC_DORx register has been loaded with the
DAC_DHRx register contents.
Note:
1
TSELx[2:0] bit cannot be changed when the ENx bit is set.
2
When software trigger is selected, the transfer from the DAC_DHRx register to the
DAC_DORx register takes only one APB clock cycle.
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Table 122. DAC trigger selection
Source
Type
TSELx[2:0]
TIM6_TRGO
Internal signal from on-chip timers
000
Reserved
-
001
TIM7_TRGO
Internal signal from on-chip timers
010
Reserved
-
011
TIM2_TRGO
Internal signal from on-chip timers
100
Reserved
-
101