GC-03: Customizable RGB Pulse LED colors via TDM mixing#372
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iROOT wants to merge 1 commit intoGissio:mainfrom
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GC-03: Customizable RGB Pulse LED colors via TDM mixing#372iROOT wants to merge 1 commit intoGissio:mainfrom
iROOT wants to merge 1 commit intoGissio:mainfrom
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Implemented customizable colors for the RGB Pulse LED on the FNIRSI GC-03. Due to a hardware design limitation (likely a shared resistor on the common anode), simultaneously enabling multiple color channels causes voltage drop issues where the red LED dominates. To solve this, a Time-Division Multiplexing (TDM) approach was introduced using TIM8 interrupts. Mixed colors (Yellow, Cyan, Magenta, White) are rendered using rapid sequential channel toggling (patterns), while primary colors remain solid. Changes: - Added "LED Color" submenu in Settings -> Pulses -> Indication. - Added 7 colors + "Rainbow" mode (cycles color on each pulse). - Implemented TDM logic in stm32_led.c using TIM8_UP_IRQHandler. - Updated gc03.h with respective R, G, B pins and timers. Note: There is a known hardware definition conflict on PB14 between the Green LED and EMFMETER_EN_PIN that needs to be addressed.
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Thanks for your PR! So EMFMETER_EN is actually GREEN_LED. Some questions:
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Hi @Gissio,
I've been working on enabling the RGB Pulse LED for the FNIRSI GC-03 and wanted to share this implementation for your review. Currently, the device is limited to a single color, but the hardware is capable of much more.
The Hardware Challenge
While testing, I noticed that the GC-03 seems to have a shared current-limiting resistor on the common anode. Because of the different forward voltages (Red ~1.8V vs Green/Blue ~3.0V), a standard GPIO high/low approach makes it impossible to mix colors—Red simply takes all the current.
The Solution: TDM Mixing
To get clean colors without hardware mods, I implemented a Time-Division Multiplexing (TDM) approach:
TIM8_UP_IRQHandlerfor mixed colors (Yellow, Cyan, Magenta, White).Implementation Details
PB14is shared between the Green LED andEMFMETER_EN_PIN. I've kept the definitions for now, but this pinout conflict should probably be addressed (e.g., remapping the EMF enable pin) to make the green channel fully usable.The concept is fully working on my device, but I’m very much open to your feedback, especially regarding the TDM architecture or the settings integration.
Thanks for all your work on Rad Pro!