basic ch1 12bit driver done by protodoatt · Pull Request #55 · WyliodrinEmbeddedIoT/tock

protodoatt · 2026-07-03T08:32:12Z

Basic STM32U545 Ch1 12bit DAC driver that implements the existing(albeit very basic) HIL.

Pull Request Overview

This pull request adds very basic driver support for CH1 of the DAC of the stm32u5xx chips. Hardcoded for 12 bit right-aligned writes without DMA.

Testing Strategy

This pull request was tested by using the DAC test inside libtock-c (the written values do have to be multiplied by 4 to get the full range as the DAC test expects 8-bit values, but I implemented 12-bit support.

TODO or Help Wanted

This pull request still needs some way to take care of (or advertise) the difference between 8 and 12 bit input values. The DAC could be set to 8 bit mode as well. I also should add some bounds check on the value before its written to the register.
The HIL could also be modified to take care of more complex DACs such as the one on the u5xx series.

Documentation Updated

Updated the relevant files in /docs, or no updates are required.

Formatting

Ran make prepush.

AI Use

The PR description details my use of AI in the production of the
code in this PR, if any, and I have manually checked and
personally certify the entire contents of this PR.

genan2003 · 2026-07-03T08:54:45Z

 impl InterruptService for Stm32u5xxDefaultPeripherals<'_> {
    unsafe fn service_interrupt(&self, interrupt: u32) -> bool {
        match interrupt {
            TIM2_IRQ => {
                // TIM2
                self.tim2.handle_interrupt();
                true
            }
            USART1_IRQ => {
                // USART1
                self.usart1.handle_interrupt();
                true
            }
            EXTI13_IRQ => {
                // EXTI13 (Button)
                self.exti.handle_interrupt(crate::exti::LineId::Line13);
                true
            }
            // Route all 16 GPDMA1 Channels to the DMA manager
            GPDMA1_CH0_IRQ => {
                self.dma1.handle_interrupt(ChannelId::Channel00);
                true
            }
            GPDMA1_CH1_IRQ => {
                self.dma1.handle_interrupt(ChannelId::Channel01);
                true
            }
            GPDMA1_CH2_IRQ => {
                self.dma1.handle_interrupt(ChannelId::Channel02);
                true
            }
            GPDMA1_CH3_IRQ => {
                self.dma1.handle_interrupt(ChannelId::Channel03);
                true
            }


Please add here the interrupt for the DAC.

Because the driver is super basic and doesn't use DMA, I don't think it needs an interrupt handler. Only writes the value to a register when called, doesn't need to wait for anything. If DMA is added in the future, then the interrupt of the DAC will be bound to one of the GPDMA channels which is already here.

genan2003 · 2026-07-03T08:55:43Z

Please document this driver. We want to see some comments on how it is working.

Sure, I'll take care of that real quick.

genan2003 · 2026-07-03T08:56:46Z

+
+    pub fn set_adcdacsel_source_hse(&self) {
+        self.registers.ccipr3.modify(CCIPR3::ADCDACSEL::HSE);
+    }
+
+    pub fn set_dac1sel_source_lsi(&self) {
+        self.registers.ccipr3.modify(CCIPR3::DAC1SEL::LSI);
+    }
+    pub fn enable_dac1(&self) {
+        self.registers.ahb3enr.modify(AHB3ENR::DAC1EN::SET);
+    }


Why do we need these?

We apparently don't, as the default clock source seems to work fine. I implemented them thinking I would need to use them to route the ADCDACSEL clock MUX during initialization, but I never needed to. They can be removed.

We apparently don't, as the default clock source seems to work fine. I implemented them thinking I would need to use them to route the ADCDACSEL clock MUX during initialization, but I never needed to. They can be removed.

If there are not used, I think we can remove them.

protodoatt · 2026-07-03T12:28:11Z

I saw clippy is throwing an error, I'll fix it

genan2003 · 2026-07-07T08:42:05Z

+
+    //DAC pin
+    periphs
+        .gpio_a
+        .pin(PinId::Pin04)
+        .set_mode(stm32u545::gpio::Mode::Analog);


Do we have only one pin from the Arduino ones that can act as a DAC?

Yes, only one routed per Channel, because I only implemented Ch1, it can only live on that pin.

genan2003 · 2026-07-08T10:54:44Z

+
+    //DAC pin
+    periphs
+        .gpio_a
+        .pin(PinId::Pin04)
+        .set_mode(stm32u545::gpio::Mode::Analog);
 }


Can you write in the comment what pin is this from the board?

genan2003 · 2026-07-08T20:45:46Z

Please use /// instead of // for the comments about registers in this driver.

genan2003 · 2026-07-08T20:46:22Z

+        (0x090 => _reserved1: [u32; 1]),
+        (0x94 => ahb3enr: ReadWrite<u32, AHB3ENR::Register>),
+        (0x98 => _reserved4: [u32; 1]),


Are this offsets reserved for a reason?

control register done basic ch1 driver complete basic ch1 driver complete(again) basic ch1 driver complete(again 2) basic ch1 dac driver with ci errors fixed basic ch1 dac driver with ci errors fixed fr this time squashed all intermediary commits Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> added bounds check and documentation Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> fixed clippy Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> Update chips/stm32u5xx/src/dac.rs Co-authored-by: Omer Genan <81963672+genan2003@users.noreply.github.com> Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> added pin comment Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> changed register comments Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> register reserved offsets explained Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com> Update chips/stm32u5xx/src/dac.rs changed copyright code Co-authored-by: Omer Genan <81963672+genan2003@users.noreply.github.com> Signed-off-by: Andrei-Tudor Tanase <protodoatt@gmail.com>

github-actions Bot added the stm32 label Jul 3, 2026

genan2003 reviewed Jul 3, 2026

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protodoatt requested a review from genan2003 July 3, 2026 12:02

genan2003 reviewed Jul 7, 2026

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genan2003 reviewed Jul 8, 2026

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protodoatt force-pushed the dac_things branch from a4ea4dc to c744735 Compare July 13, 2026 08:55

protodoatt force-pushed the dac_things branch from c744735 to 0cab156 Compare July 13, 2026 08:59

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protodoatt commented Jul 3, 2026

Pull Request Overview

Testing Strategy

TODO or Help Wanted

Documentation Updated

Formatting

AI Use

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protodoatt commented Jul 3, 2026

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