Photonicat 2 LED Indicator

Photonicat 2 has a single two-colour indicator LED (red + green). Yellow/orange is produced by lighting both colours together; there is no blue.

The indicator follows a MacBook-style scheme:

• Colour tells you the charge state — 🟠 yellow = charging, 🟢 green = charged.
• Motion tells you the machine state — breathing = system running, steady = system off.

Applies to firmware RA2E1260726001 and later. Earlier firmware did not distinguish system on/off while charging or charged.

Since RA2E1260731011 the charging orange is warmer (R60 %/G24 % instead of R55 %/G35 %), the breath fades only to a dim-orange floor (≈1/12 of peak) before the valley off — on earlier firmware the dim ends of each breath cycle could look pure red — and the valley off hold is 0.5 s instead of 0.24 s (cycle ≈6.1 s).

Since RA2E1260802000: trying to power on with a flat or too-low pack flashes red three times immediately (earlier firmware showed nothing, so a flat device looked bricked), and a short press while off with a low pack shows the same three flashes. Continuous red flashing is only used while the system is running. The power-button long press is now 1.5 s.

Fixed in RA2E1260805000: on RA2E1260802000–RA2E1260802001 a short press while the device was off in standby could flash red three times even with a full battery — the voltage sensor briefly reads 0 mV while waking from standby and this was miscounted as low battery. Red now requires a genuine low-voltage reading.

Since RA2E1260808001: with the system off and the battery below the minimum boot voltage (6600 mV), any press of the power button answers with the three red flashes right away — about 0.1 s into the press, before the system power rail is touched — and the device then drops back into deep sleep to preserve the last battery reserve for the built-in clock. On RA2E1260802000–RA2E1260808000 the refused-boot flashes only appeared after holding the full 1.5 s long press and releasing; a shorter press showed nothing until release. Also fixed in this version: if the continuous low-battery warning was flashing when the system shut down (including the automatic 6300 mV shutdown), earlier firmware never cancelled it — the red kept flashing indefinitely after the system was off and prevented the controller from sleeping, draining the remaining battery. It now stops at shutdown.

中文版见 Photonicat 2 LED 指示灯. For buzzer tones see Photonicat 2 Sound Guide.

Quick reference

The animations below are illustrative; their timing matches the firmware (≈6.1 s breathing cycle, 2 s heartbeat).

Animation	Indicator	Meaning
	🟠 Yellow, breathing	Charging, system running
	🟠 Yellow, steady	Charging, system off
	🟢 Green, breathing	Fully charged (or at charge limit), system running
	🟢 Green, steady	Fully charged (or at charge limit), system off
	🟢 Green, heartbeat pulse	Running on battery, charge level normal
	🔴 Red, flashing	Low battery (below 6500 mV — see Low battery red light)
	⚫ Off	Idle on battery, system off

Full state table

Battery thresholds are firmware defaults and can be overridden by the host. Values are for the 2S pack: full 8280 mV, low warning 6500 mV, minimum boot 6600 mV, hard shutdown 6300 mV.

Power level	Charger	Animation	Colour	Pattern	Timing
Charging, any level	Connected		🟠 Yellow	Breathing (system on)	2.8 s up / 2.8 s down / 0.5 s off, ≈6.1 s cycle; fades to a dim-orange floor (≈peak/12), never pure red
Charging, any level	Connected		🟠 Yellow	Steady (system off)	Constant
Full, or at charge limit	Connected		🟢 Green	Breathing (system on)	Same ≈6.1 s cycle, after 10 s delay
Full, or at charge limit	Connected		🟢 Green	Steady (system off)	Constant, after 10 s delay
Below 6600 mV, DC ≥ 8 V, no charge current	Connected		🟠 Yellow	Steady	Constant
Above 6500 mV, system on	None		🟢 Green	Heartbeat pulse	2 s period
Above 6500 mV, system starting	None		🟢 Green	Steady	Constant
Above 6600 mV, system off	None		🟢 Green	Steady	Constant
Below 6500 mV, system on	None		🔴 Red	Continuous flashing	1 s on / 1 s off, begins after 60 s, until the voltage recovers
Below 6500 mV (valid reading), short press, system off	None		🔴 Red	Flicker	1 s on / 1 s off, 3 flashes, first flash immediate (0.5 s debounce)
Below 6600 mV, any power-button press, system off	None		🔴 Red	Flicker	3 flashes, first flash ≈0.1 s into the press (since RA2E1260808001; earlier firmware flashed only after releasing a full 1.5 s long press). The system power rail is never touched; the device returns to deep sleep afterwards
Charger removed, system off	None		⚫ Off

Service and transitional states

These override the states above.

State	Animation	Colour	Pattern	Timing
Shutting down		🟢 Green	Blink	≈0.5 s on / 1.5 s off
Firmware download mode		🟠 Yellow	Fast blink	≈0.5 s period
Reset / factory restore mode		🟠 Yellow	Slow blink	≈1 s period

Low battery red light

When the battery runs low the indicator turns 🔴 flashing red. This is the only situation in which red is used.

Item	Detail
Trigger	Battery below 6500 mV (2S pack, about 3.25 V per cell) with no charger connected
Rhythm	1 second on / 1 second off
Repeats	System running: flashes continuously until the voltage recovers or a charger is connected. System off (any power-button press): exactly 3 flashes, then the device goes back to deep sleep
While running	Starts only after the voltage has stayed below the threshold for 60 seconds
Any press while off	With the battery below the boot threshold, any press of the power button flashes red three times, starting about 0.1 s into the press (since RA2E1260808001); the device then returns to deep sleep. A 0 mV sensor warm-up reading right after standby wake does not count — the firmware takes a fresh voltage sample before deciding (since RA2E1260805000)
Effect on green	The green heartbeat stops while red is active; the two never show together

⚠️ Important

• While the system is running, the red warning keeps flashing until the voltage recovers or a charger is connected; it does not stop on its own. (Firmware before RA2E1260726003 flashed only 3 times and then went quiet.) While the system is off, short press and refused power-up flash exactly 3 times so the MCU can return to standby.
• The red threshold (6500 mV) is only 200 mV above the hard shutdown point (6300 mV). That is a very steep part of the 2S li-ion discharge curve, so connect a charger promptly once you see red.
• The trigger is voltage, not a percentage. Under heavy load the voltage sags and the warning can appear while a useful charge remains; when the load drops the voltage recovers and the warning stops.

Charge limit

If a charge limit is configured (for example 80 %), the charger is switched off once the pack reaches it. Charge current drops to zero, so the device treats this as fully charged and shows 🟢 green. The pack then powers the load and slowly discharges until it falls below the resume threshold, at which point charging restarts and the indicator returns to 🟠 yellow. Each transition is delayed by about 10 seconds.

Notes

• Green breathing peaks at 25 % duty while steady green is 50 %, so breathing green looks dimmer than steady green. Orange breathing peaks at the same R60 %/G24 % mix as steady orange.
• 🔴 Red is only ever used for low battery. While the system is running it keeps flashing until the voltage recovers or a charger is connected; while off it flashes exactly three times.
• The indicator can be disabled through the host protocol, in which case all green/yellow states stay off. The 🔴 low-battery red warning is exempt since RA2E1260808001: it is a system-level alert and flashes even with the indicator disabled, so a flat pack refusing to boot never looks dead. (Before that version, disabling the indicator silenced red too.)
• For how the charge level behind these indications is computed, see Photonicat 2 SOC Calculation.