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Summary
Great hardware, poor software – that’s the Sofirn SK31 in a nutshell. The combination of a powerful LMP LHP73B with a well-regulated driver, a two-stage tail switch, a separate switch for the lockout and a screwed cover for the USB-C charging port provide the perfect hardware foundation for a great flashlight.
The operation is all the more disappointing. The two-stage switch leaves much of its potential unused. For example, there is no direct access to the lowest or highest brightness level and in Tactical Mode, the switch must be held halfway down for a full five seconds to keep the flashlight on. Minor firmware bugs make the overall experience even less enjoyable.
The full review is available here:
English review at BudgetLightForum
German review on my website
That is often not even software but a series of hardware logic gates or something like sn SLV46826 which is a kind of mini-fpga that is super easy to work with.
Firmware would only really be needed for smooth dimming or complex button sequences.
https://www.digikey.com/en/products/detail/renesas-electronics-corporation/SLG46826V/10383644
Nobody is going to use a $2 FPGA in a flashlight when they can use a 5 cent microprocessor.
A bit disingenuous comparing the absolute lowest of the low shit-tier MCU at 240,000 quantity (on digikey) to literally buying qty 1 individual high quality components.
I could also argued in bad faith and say, why use a 900€ MCU when you can use a $1 FPGA https://www.digikey.be/nl/products/detail/rochester-electronics-llc/MQ80C196KB-12/12599296
Plus that 5¢ MCU will drain your flashlight battery fully in less than half a year. Even a more expensive, but still cheap one the CH32V003 has a 0.6mA sleep current that drains an 18650 in 250 days or so. Quality flashlights and headlamps last years without charging under very light use. They use these kind of FPGAs or specialized ICs like the Azoteq (black diamond headlamps) IQS318 that has 4-15uA consumption and are 30¢ or so.
No idea about the CH32V003 but the Padauk MCU (3 cents in qty 1000 on LCSC iirc) has near zero current drain in the deepest sleep mode. Here's a LED blinker with a Padauk (I think not the 3 cent model but not much more) using 1 microamp on average, works out to 22 years on a cr2032 coin cell: https://cpldcpu.wordpress.com/2021/02/07/ultra-low-power-led-flasher/
Anduril currently relies on AVR series MCU's and sleep current is also in the microamp range. Anyway take apart some flashlights made in the past 10 years, before telling me that any but the simplest ones don't have microprocessors.
Added: the CH32V003 appears to have a standby mode using 10 to 11 microamps. https://curiousscientist.tech/blog/ch32v003j4m6-low-power-modes