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M451
May. 4, 2018
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6.23.4 Basic Configuration
The DAC output pin is configured in SYS_GPB_MFPL[3:0] Multi-function Register. The DAC
Controller clock source is enabled by DACCKEN (CLK_APBCLK1[12]).
6.23.5 Functional Description
DAC Output
6.23.5.1
The DAC is a 12-bit voltage output digital-to-analog converter. The DAC integrates a voltage
output buffer that can be used to reduce output impendence and drive external loads directly
without having to add an external operational amplifier. The DAC channel output buffer can be
enabled and disabled by BYPASS (DAC_CTL[8]). The maximum DAC output voltage is limited to
the selected reference voltage source.
DAC Reference Voltage
6.23.5.2
The DAC reference voltage is shared with EADC reference voltage and it is configured by
VREFCTL (SYS_VREFCTL[4:0]) in system manager control registers. The reference voltage for
the DAC can be configured from external reference voltage pin (V
REF
) or internal reference
voltage generator (INT_VREF).
DAC Data Format
6.23.5.3
The DAC supports conversion data left alignment or right alignment mode. Depending on the
selected configuration mode, the data needs to be written into the specified register as follows:
12-bit left alignment: user has to load data into DAC_DAT[15:4] bits. DAC_DAT[31:16] and
DAC_DAT[3:0] are ignored in DAC conversion.
12-bit right alignment: user has to load data into DAC_DAT[11:0] bits, DAC_DAT[31:12] are
ignored in DAC conversion.
31
23
0
11
31
23
0
4
Right Aligned
Left Aligned
15
15
7
7
DAC_DAT[15:4]
DAC_DAT[11:0]
Figure 6.23-2 Data Holding Register Format
DAC Conversion
6.23.5.4
Any data transfer to the DAC channel is performed by loading the data into DAC_DAT register.
Figure 6.23-3 shows the DAC conversion started by software write operation. When user writes
the conversion data to data holding register DAC_DAT, the data is loaded into data output
register DAC_DATOUT by hardware and DAC starts data conversion after one PCLK (APB clock)
clock cycle. Figure 6.23-4 shows the DAC conversion started by hardware trigger (external pin
STDAC, timer trigger event or PWM timer trigger event). The data stored in the DAC_DAT
register is automatically transferred to the data output buffer DAC_DATOUT after occurring one
PCLK (APB clock) the event.
When DAC data output register DAC_DATOUT is loaded with the DAC_DAT contents, the analog
output voltage becomes available after specified conversion settling time. The conversion settling
time is 8us when 12-bit input code transition from lowest code (0x000) to highest code (0xFFF).
Содержание ARM Cortex NuMicro M451 Series
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Страница 355: ...M451 May 4 2018 Page 355 of 1006 Rev 2 08 M451 SERIES TECHNICAL REFERENCE MANUAL 2 0 Reserved Reserved...
Страница 625: ...M451 May 4 2018 Page 625 of 1006 Rev 2 08 M451 SERIES TECHNICAL REFERENCE MANUAL 00 5 bits 01 6 bits 10 7 bits 11 8 bits...
Страница 721: ...M451 May 4 2018 Page 721 of 1006 Rev 2 08 M451 SERIES TECHNICAL REFERENCE MANUAL the SCL line 1 0 Reserved Reserved...
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Страница 1002: ...M451 May 4 2018 Page 1002 of 1006 Rev 2 08 M451 SERIES TECHNICAL REFERENCE MANUAL LQFP 64L 7x7x1 4 mm footprint 2 0 mm 9 3...
Страница 1003: ...M451 May 4 2018 Page 1003 of 1006 Rev 2 08 M451 SERIES TECHNICAL REFERENCE MANUAL LQFP 48L 7x7x1 4mm footprint 2 0mm 9 4...