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ashishgawade
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ashishgawade
Asked: May 8, 2023In:
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Hello, I just entered my brand new stm32h747 discovery board, on power-up it does nothing just two LEDs light up, according to the user primer it should be preloaded with a demo. I checked in Cube Prog and it reports as blank. Is ...Read more

Hello,

I just entered my brand new stm32h747 discovery board, on power-up it does nothing just two LEDs light up, according to the user primer it should be preloaded with a demo.

I checked in Cube Prog and it reports as blank.

Is it possible that my device got damaged ever or it’s just not flashed? aren’t units tested before dispatching out?

Is this a common thing? I do not flash back ever entering a discovery board blank.

Thank You

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boardcubeflashledspowerstm2h747
  1. vikas Nagpal

    Hello, In actuality, the DISCOVERY is always delivered pre-programmed. Depending on where you got the board, a possible former owner may have canceled its flash. still, it shouldn't be a problem to reprogram the board and the external flash memory, as the collected demo can be set up on the STM32H74Read more

    Hello, In actuality, the DISCOVERY is always delivered pre-programmed. Depending on where you got the board, a possible former owner may have canceled its flash.

    still, it shouldn’t be a problem to reprogram the board and the external flash memory, as the collected demo can be set up on the STM32H747I–DISCO product website under Documentation> collected Demos, after unbarring in the subfolder STM32H747I-DISCO_demo/Binary.

    Does it answer your question?

    Regards

    Vikas Nagpal

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vikas Nagpal
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vikas Nagpal
Asked: March 6, 2023In:
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Hello, After looking over all the documentation I could find (datasheet, source primer, etc.), I couldn’t easily find how I’m meant to connect IR LED (s) for Ir DA communication with an STM32WB55. The image I attached is a screenshot from ...Read more

Hello,

After looking over all the documentation I could find (datasheet, source primer, etc.), I couldn’t easily find how I’m meant to connect IR LED (s) for Ir DA communication with an STM32WB55. The image I attached is a screenshot from the reference primer, which implies that there may be IrDA_OUT and, IN pins (I am interpreting this as being separate from the TX and RX pins). Am I supposed to add some intermediate IC for Ir DA, or can the STM32WB55 actually output signals for driving/ reading IR LEDs photodiodes?

I am aware of the actuality of the IR_OUT pins, but that’s its own separate thing. In the IR_OUT documentation, they use only timers (TIM16 & TIM17), not the US ART supplemental.

Thanks and Regards

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datasheethardwareirdaledsphotodiodesstm32wb55
  1. Julian White

    Hello, IrDA has hardly been used for a long time, which is also marked in discontinued IrDA transceivers. However, since basically everything except the TIA and visual factors is included in the STM32 IrDA SIR ENDEC, it's possible to recreate IrDA with an IR LED plus driver transistor and an IR photRead more

    Hello,

    IrDA has hardly been used for a long time, which is also marked in discontinued IrDA transceivers. However, since basically everything except the TIA and visual factors is included in the STM32 IrDA SIR ENDEC, it’s possible to recreate IrDA with

    • an IR LED plus driver transistor and
    • an IR photodiode plus TIA.

    RX and TX are switched to the IrDA function so that the LED driver and TIA can be connected directly.

    Regards

    Julian White

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nidhi singh
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nidhi singh
Asked: December 1, 2022In:
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Hello, What is the difference between Parts L9826 and Parts E-L9826？ I can not see the difference between them from the datasheets. Thank you in Advance

Hello,

What is the difference between Parts L9826 and Parts E-L9826？ I can not see the difference between them from the datasheets.

Thank you in Advance

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datasheetse-l9826l9826ledsopteolectronicspower management
  1. ashishgawade

    There's no technical difference between L9826 and E-L9826. At the time, the version with the prefix E- indicated the more environmentally friendly Eco version, which has been standard for a long time. still, please mark this thread as answered by selecting Select as best, as also explained then, IfRead more

    There’s no technical difference between L9826 and E-L9826. At the time, the version with the prefix E- indicated the more environmentally friendly Eco version, which has been standard for a long time.

    still, please mark this thread as answered by selecting Select as best, as also explained then, If the problem is solved. This will help other users find that answer faster.
    Regards

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Alex thomas
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Alex thomas
Asked: October 4, 2022In:
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I’ve read quite a bit about needing a resistor when powering a 5 mm LED from an esp32 GPIO pin, still, other experts say that if a LED is powered right, it will not need a resistor at all will ...Read more

I’ve read quite a bit about needing a resistor when powering a 5 mm LED from an esp32 GPIO pin, still, other experts say that if a LED is powered right, it will not need a resistor at all will not burn out.

1. Is it as easy as purchasing a LED that’s powered properly for an esp32 GPIO pin so that it will not probably burn out in a reasonable amount of time( years)?
2. Still, what’s the current on each GPIO pin? ( I know that the voltage on each GPIO pin is 3, If so.3 V)
3. Rather than adding a resistor, I can add a second LED parallel to add resistance and meet the power requirements, right?

Thanks!

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esp32gpioledspin
  1. nidhi singh

    The maximum power per pin is 40mA. You shouldn't push more than 150 mA through all your output pins( and probably less than that to avoid overheating). You can find the correct resistor value using any led resistor calculator online and the datasheet for your led. I do not see how parallel resistorsRead more

    The maximum power per pin is 40mA. You shouldn’t push more than 150 mA through all your output pins( and probably less than that to avoid overheating). You can find the correct resistor value using any led resistor calculator online and the datasheet for your led. I do not see how parallel resistors will be useful if you’re powering directly through the pin, and you do not have to get the exact resistance calculated. However, you should have a transistor gating a separate power supply for the light, If you need more than milliamps.

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Alex thomas
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Alex thomas
Asked: September 24, 2022In:
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Internal Low-Side Switch in LED5000?

What’s the purpose of the internal low-side switch in LED5000? Is it a synchronous converter? If so, also why is an external Schottky shown in the application diagrams?

What’s the purpose of the internal low-side switch in LED5000? Is it a synchronous converter? If so, also why is an external Schottky shown in the application diagrams?

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led5000ledsoptoelectronics
  1. Best Answer
    ashishgawade

    Yes, it works in synchronous mode. still, after the low-side FET has been switched off, there's always a specific dead time while the inductor still drives current. That current would flow through the body diode of the low-side FET, reducing effectiveness and increasing the radiated noise. This behaRead more

    Yes, it works in synchronous mode.

    still, after the low-side FET has been switched off, there’s always a specific dead time while the inductor still drives current. That current would flow through the body diode of the low-side FET, reducing effectiveness and increasing the radiated noise. This behavior can be improved by using a Schottky that takes over the current during the dead time.

    When your question is answered, please close this content by choosing Select as Best. This will help other users find that answer faster.

    Good luck!

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ashishgawade
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ashishgawade
Asked: September 19, 2022In:
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We’re using the L6920 to drive a 1-watt LED. We’re trying to apply the under voltage cut-off ( lockout) too. We chose the values of the voltage ground connected to the LBI pin similar that the value that comes to say ...Read more

We’re using the L6920 to drive a 1-watt LED.

We’re trying to apply the under voltage cut-off ( lockout) too. We chose the values of the voltage ground connected to the LBI pin similar that the value that comes to say 3V. Still, the IC didn’t shut off at 3V.
We also tried connecting the LBO to Vout with a 200K resistor in between. Even this didn’t work.

Can someone help apply this circuit?
Thanks!

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circuitdriveICl6920ledsoptoelectronics
  1. Best Answer
    Alex thomas

    Hi Ashish, However, you would notice that LBI input is connected to LBO output and that's the only purpose of this input, If you look into the block diagram of L6920 in its datasheet. LBI input doesn't shut down the output! Still, you need to use LBO output to shut down accordingly, If you require tRead more

    Hi Ashish,

    However, you would notice that LBI input is connected to LBO output and that’s the only purpose of this input, If you look into the block diagram of L6920 in its datasheet. LBI input doesn’t shut down the output!
    Still, you need to use LBO output to shut down accordingly, If you require to shut down the output.

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nidhi singh
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nidhi singh
Asked: September 7, 2022In:
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Hello I’m developing an operation that does led control with a button, I use a counter for this, but every time I hold the button, the counter increases further than 1 So indeed if I hold the button down, I want ...Read more

Hello

I’m developing an operation that does led control with a button, I use a counter for this, but every time I hold the button, the counter increases further than 1 So indeed if I hold the button down, I want it to increase once.

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buttoncontroldevelopingledsoptoelectronics
  1. vikas Nagpal

    Perhaps you should debounce the button, as mechanical buttons bounce, i.e. may produce more than one pulse per button press. There are several techniques to do that, one of the easiest is to connect some small capacitor in parallel to the button, which together with the pull resistor forms some lowRead more

    Perhaps you should debounce the button, as mechanical buttons bounce, i.e. may produce more than one pulse per button press.

    There are several techniques to do that, one of the easiest is to connect some small capacitor in parallel to the button, which together with the pull resistor forms some low pass filter. The time constant of that filter should be slightly lower than the period of the maximum speed to press that button(e.g.100.200 ms). You’ll find this solution also at the NUCLEO or DISCOVERY boards.

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Alex thomas
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Alex thomas
Asked: August 31, 2022In:
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I’ve 36 leds on my board. I’ll connect dimmer my board. How can i adjust leds brightness with dimmer? Because i need to manage 36 output pins. How can i do it?

I’ve 36 leds on my board. I’ll connect dimmer my board. How can i adjust leds brightness with dimmer? Because i need to manage 36 output pins. How can i do it?

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brightnessdimmerledsstm32
  1. vikas Nagpal

    You can DMA to the io pins (using a indirect buffer, transferring to GPIO output register). I controlled 48 Leds (16 RGB Leds) this way using a STM32L4(100 LQFP package). But this was to give independent brightness situations to each individual Led. But if all Leds are dimmed together (synchronised)Read more

    You can DMA to the io pins (using a indirect buffer, transferring to GPIO output register). I controlled 48 Leds (16 RGB Leds) this way using a STM32L4(100 LQFP package). But this was to give independent brightness situations to each individual Led.

    But if all Leds are dimmed together (synchronised), also you probably only need a single FET to sink all the Leds current, and use that FET to control the brightness (PWM)

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