cpu/sam0_common: enable static voltages#21555
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benpicco merged 3 commits intoRIOT-OS:masterfrom Jun 23, 2025
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DAC_CTRLA_SWRST clears all registers, so it also clears the config of the first DAC line after configuring the second DAC line.
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Platform: ARM
maribu
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Type: enhancement
benpicco
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| /* Settings can only be changed when DAC is disabled, reset config */ | ||
| DAC->CTRLA.reg = DAC_CTRLA_SWRST; | ||
| /* Settings can only be changed when DAC is disabled */ | ||
| DAC->CTRLA.reg &= ~DAC_CTRLA_ENABLE; |
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Since there are only two bits, you could also just
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| DAC->CTRLA.reg &= ~DAC_CTRLA_ENABLE; | |
| DAC->CTRLA.reg = 0; |
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For some CPUs there are three bits. One of them is the bit to enable operation during standby power mode:
typedef union {
struct {
uint8_t SWRST:1; /*!< bit: 0 Software Reset */
uint8_t ENABLE:1; /*!< bit: 1 Enable */
uint8_t RUNSTDBY:1; /*!< bit: 2 Run in Standby */
uint8_t :5; /*!< bit: 3.. 7 Reserved */
} bit; /*!< Structure used for bit access */
uint8_t reg; /*!< Type used for register access */
} DAC_CTRLA_Type;
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But now you are writing the entire CTRLA reg anyway at the end, you might as well set it all to 0 here 😉
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But 0 feels like a magic number to me and I like the fact that clearing the bit makes the intention clear.
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Well it saves two instructions - but yea, not really that much relevant on init.
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Contribution description
The DAC needs to set up a conversion refresh in order to hold a static voltage, so just do it by default. Also add the option to keep the DAC running during standby mode.
Testing procedure
Can be tested with
tests/periph/dac/main.ce.g. on asame54-xpro.Issues/PRs references
Fixes a configuration issue introduced by #21548