Nucleo-F410RB DAC hardwired to a (green) LED ?

[ker2x]

Friendly greetings !

i had found, ordered and canceled the board with the perfect MCU.

• M4
• ADC
• DAC
• DSP
• And more, but I really wanted that DSP and DAC

1. I install STM32CubeMX on my Mac M1 (with some troubles at first, but it works).
2. I select the board I just ordered.
3. Let the software do its stuff and then the DAC configuration is in RED in the "pinout & configuration" panel because it conflict with GPIO PA5.
4. GPIO PA5 have the user label "LD2 [Green LED]"

I'm flabbergasted. This is ridiculous, right ? why would I want a 1MS 12Bit DAC on a led ?

Despite my best effort browsing the documentation, as a beginner to the STM ecosystem, I understand that it's hardwired to PA5:

Table 9. STM32F410x8/B pin definitions, page 36/143 of the STM32F410x8 STM32F410xB datasheet.

 

Is the PA5 really hardwired to a (green) led on this board ?

Is there something I can do to use the DAC ?

Can the pinout be changed ?

Is there another M4 board in a < 100 euro price range with DAC & DSP ?

(i also ordered an Adafruit board at the same time with a microchip mcu in order to try their circuit python thing, but I would like to have a STM board too )

Thank you.

[KnarfB]

> Is the PA5 really hardwired to a (green) led on this board ?

Yes, it looks like. Cf. board schematics https://www.st.com/en/evaluation-tools/nucleo-f410rb.html#cad-resources

> Is there something I can do to use the DAC ?

Yes, here is a solder bridge SB21 which you could open, i.e. remove the zero Ohm link on the bottom side.

> Can the pinout be changed ?

Not for the DAC. You can remove the LED GPIO function in CubeMX and then configure the DAC output.

hth

KnarfB

[Tesla DeLorean]

>>Is the PA5 really hardwired to a (green) led on this board ?

All the boards has schematics, see "CAD Resources" on the product page

https://www.st.com/en/evaluation-tools/nucleo-f410rb.html#cad-resources

https://www.st.com/resource/en/schematic_pack/nucleo_64pins_sch.zip

PA5 is exposed at the D13 pin of the ARDUINO rail.

Some F4 had 2x DAC

>>I'm flabbergasted. This is ridiculous, right ? why would I want a 1MS 12Bit DAC on a led ?

Higher pin count devices afford more options and freedom.

What you want is not what the next guy wants.

TBH a lot of design choices in these parts seem to have been made in meeting rooms with high CO2 levels. So a lot of awkward, inflexible and unhelpful choices. There's very little "dog fooding" in large orgs, so often people making the most critical design choices aren't those who are impacted by them.

>>Is there something I can do to use the DAC ? Can the pinout be changed ?

Do you possess a soldering iron? These things can be modified, especially if you look at the schematic and identify the pins/nodes the signals go through. Float off parts, or cut traces.

>>Is there another M4 board in a < 100 euro price range with DAC & DSP ?

Aren't there a raft of NUCLEO's in the sub 30 USD/EURO range

Look critically at the schematics.

>>DSP

It has some routines, instructions and some math support

Some of the H7 have an FPU that can do double (64-bit) floats. All the ARM FPU lack the sort of transcendental functions of the Intel ones.

The G4 has CORDIC support

https://www.st.com/resource/en/application_note/dm00614795-getting-started-with-the-cordic-accelerator-using-stm32cubeg4-mcu-package-stmicroelectronics.pdf

https://www.st.com/content/ccc/resource/training/technical/product_training/group0/df/3d/f3/88/05/ae/42/67/STM32G4-Peripheral-Cordic_Coprocessor_CORDIC/files/STM32G4-Peripheral-Cordic_Coprocessor_CORDIC.pdf/jcr:content/translations/en.STM32G4-Peripheral-Cordic_Coprocessor_CORDIC.pdf

[KnarfB]

Look with CubeMX at STM32G474RE or the smaller STM32G431RB Nucleo boards as a possible alternative.

hth

KnarfB

[ker2x]

thank you for the additional info. I didn't notice the D13 pin, I got stuck at the CubeMX stage.

I ordered the MC based barebone M4 board from adafruit, and will probably order the STM version of the board in the future.

This CORDIC thing looks both confusing and interesting. it certainly is an original solution (It probably exist elsewhere but it's the first time I see this way of doing trigonometry)

[ker2x]

Yup, thx 🙂

[Nikita91]

You can une your board without change.

The output of the DAC goes directly from PA5 to CN5 pin 6 so you can use it. The only side effect will be that the LED will reflect the level generated by the DAC.

[waclawek.jan]

Given the relatively low output current of DAC, even with buffer on (which limits its voltage range), I'd open the SB as KnarfB said in his first reply.

JW

[Nikita91]

You are right. I should have read the datasheet more carefully...