HaloKeymind/docs/radio_profiles.md

Two LoRa profiles on one radio

radio2 lets one LoRa transceiver alternate between two frequencies or modulation settings. It is useful for listening to two networks, or keeping your usual channel available during a LoRa firmware update.

There are at most two active profiles. tempradio temporarily replaces radio; tempradio2 temporarily replaces radio2. These are time-shared receive windows, not simultaneous receivers. Receiving or transmitting a packet on one profile makes the other unavailable until that packet finishes.

The second-profile commands are shared by repeater, Companion, room server, sensor and standalone terminal-chat firmware with a LoRa radio. ESP-NOW-only devices reject LoRa profile commands. KISS is a raw host-controlled modem and does not expose these Mesh CLI commands or Mesh retry queues.

Quick setup

Keep the primary channel configured with radio, then add the second:

set radio2 910.5,500,8,5,rx
get radio2
get radio2.status

The tuple is frequency in MHz, bandwidth in kHz, spreading factor, coding-rate denominator, mode, optional preamble in symbols. 5 means coding rate 4/5.

Mode	Receive on profile 2	Transmit on profile 2
rx	Yes	No
rxtx (also rx&tx)	Yes	Yes
off	No	No

For transmission on both permanent profiles:

set radio2 910.5,500,8,5,rxtx

The same encoded message is queued separately for each allowed transmit profile. Each has its own direct/flood retry slots and channel-busy backoff. A forwarding echo on one profile cannot cancel the other profile's retry. Packet storage and the physical transceiver's airtime budget are shared; exhausted queues can still drop packets.

Keep the main channel during an update

set tempradio2 910.5,500,8,5,rxtx,120
get tempradio2

This enables the second profile for 120 minutes (2 hours). Locally generated LoRa OTA packets use the temporary second profile. Ordinary local traffic stays on the primary profile by default. Use an OTA-capable build and the usual OTA setup on every participating node; a temporary profile does not add OTA support to firmware built without it.

New settings take effect after a short reply allowance. Temporary periods and schedules live in RAM and disappear on reboot. Timer expiry also uses monotonic time, so setting the clock backwards cannot extend a temporary session.

Companion messages on both profiles

To send ordinary Companion messages on both radio and an active tempradio2, configure the temporary profile in rxtx mode and enable crossing:

set radio2.cross on
get tempradio2
get radio2.cross
get radio2.status

rxtx permits transmission on the second profile; radio2.cross on copies new messages between the two profiles. TX=a,b reports primary and secondary transmit counts. Crossing also applies to OTA traffic.

The crossing setting is saved and remains enabled after the temporary session ends or the node reboots. Run set radio2.cross auto to restore the default isolation between permanent and temporary profiles. The firmware picker's Companion tempradio2 instructions include both choices and the status commands.

Choose whether traffic crosses between profiles

get radio2.cross
set radio2.cross auto
set radio2.cross on
set radio2.cross off

Active primary	Active secondary	auto (default)	on	off
radio	radio2	Cross	Cross	Isolated
tempradio	tempradio2	Cross	Cross	Isolated
radio	tempradio2	Isolated	Cross	Isolated
tempradio	radio2	Isolated	Cross	Isolated

Crossing always respects rx: nothing transmits on an RX-only second profile. With crossing allowed, a packet received there may still be forwarded on the primary profile. Existing routing, forwarding and packet-filter settings apply. An RX-only tempradio2 also blocks locally generated OTA transmissions under auto or off; they do not fall back to the normal primary channel. Use rxtx for an update session that needs to exchange requests and data.

Preamble

Append the preamble to the end of a command:

set radio2 910.5,500,8,5,rxtx,88
set tempradio2 910.5,500,7,5,rxtx,120,128
set radio 909.5,62.5,7,5,32
set tempradio 909.5,62.5,7,5,120,32

Existing primary radio, tempradio, radioat and tempradioat commands accept the optional trailing preamble where those primary commands are supported by the role. Getters include the preamble. Omit it, or use auto/0, to calculate it automatically. Explicit values are used as entered, subject to the radio's limits and safe airtime arithmetic.

Automatic dual-profile preambles round up to a multiple of eight, with a 32-symbol minimum. Each idle scan starts with 4.6 symbols on the slower profile, then spends the remaining budgeted time on the faster profile, also with a 4.6-symbol floor. Slower means a longer LoRa symbol (2^SF / bandwidth), regardless of profile number. The slower preamble sets the return deadline. The calculation allows two slow visits within that preamble, reserving 0.6 ms per switch and 0.3 ms of main-loop margin. Fast-channel transmit preambles include sixteen acquisition symbols. For a primary SF7 / 62.5 kHz profile:

Secondary profile	Automatic secondary preamble	Previously tested explicit preamble	Primary preamble
SF9 / 500 kHz	32	32	32
SF8 / 500 kHz	88	64	32
SF7 / 500 kHz	64	80	32

With preamble 32 on that slower profile, its visit is 9.421 ms and the faster visit is 21.847 ms, plus the actual switching time. Increasing the slow preamble also increases the time available on the fast channel. If the symbols are equal in length, the primary profile goes first. Detected packets hold the current channel until reception finishes.

The SF8 / 500 kHz value also retains the measured 88-symbol floor from the production V4/XIAO tests, where 72 and 80 each missed a packet. The explicit values come from the production validation: the final fast-channel attempts each received 50/50 packets at 4.8 slow symbols. Automatic values use the switching and loop-jitter allowances below. Those explicit-preamble tests used the older 4.8-symbol policy; they do not validate the new 4.6-symbol slow dwell / 0.3 ms reserve. The 4.6/0.3 ms two-profile bench received 197/200 at SF7/62.5 + SF8/500 with explicit 32-symbol preambles. The newer four-channel 5.1/6.1/7.7 tests also had misses, so this is a timing policy, not a claim of zero packet loss. The automatic fast preamble covers the blind interval during the slow visit, both switches and the acquisition margin. These settings do not guarantee reception during overlapping packets or long pauses in the firmware loop. Transmitters on each channel also need a long enough preamble. Changing the receiver's setting does not lengthen packets sent by other nodes.

Chirp calculator and warnings

get radio2.timing (alias get radio.timing) reports the active pair in radio,radio2 order: dwell in chirps, recommended preambles in symbols, and the switching/loop allowances. For SF7/62.5 on radio and SF7/500 on radio2:

> chirps=4.60,85.34; need=32,64; switch=600us; loop=300us (estimate); WARN recommended preamble: radio2=64

WARN recommended preamble identifies each profile whose recommendation exceeds the standard 32 symbols or its explicitly selected value. For example, with SF7/62.5 on the primary profile, set radio2 910.5,500,7,5,rx,32 replies:

OK - radio2 rx; preamble=32; WARN recommended preamble: radio2=64; short override: radio2

Successful set radio ... replies also include the recommended preamble for each affected profile, calculated with the requested settings. A short override note identifies an explicit value below the estimate; it is not silently rewritten. Warnings are also included in profile settings/getters, scan info, temporary settings and schedule acknowledgments. off disables the dual-profile warning. A timing readout does not change settings or transmit a packet.

The shared RadioProfiles::calculateChirpTiming() function accepts both tuples, optional visit times in microseconds, a per-switch allowance and loop margin. Using microseconds throughout:

T[i] = 2^SF[i] * 1000 / BW_kHz[i]
slow = profile with the longer T (radio wins ties)
L[slow] = max(requested_visit_us[slow], ceil(4.6 * T[slow]))
L[fast] = max(requested_visit_us[fast], ceil(4.6 * T[fast]))
O    = 2 * switch_us + loop_margin_us
C    = L[radio] + L[radio2] + O

P[slow] = round_up_to_8(max(32, 2 * C / T[slow]))
P[fast] = round_up_to_8(max(32, (L[slow] + O) / T[fast] + 16))

The previous SF8/500 versus SF7/62.5 measured 88-symbol floor remains in force. Automatic selection uses the minimum visits to choose a preamble, then allocates the fast visit from half the slow preamble's duration. Diagnostics feed the actual allocated visits back into the same function, including longer visits caused by an explicit slow preamble. Too-short slow preambles that cannot fit both minimum visits remain rejected by the existing configuration validation.

The automatic scheduler uses these same role-specific minima and computes:

slow_dwell = ceil(4.6 * T[slow])
fast_dwell = max(ceil(4.6 * T[fast]),
                 floor(P_configured[slow] * T[slow] / 2 - slow_dwell - O))

For the tested SF7/62.5 + SF8/500 pair with slow preamble 32, this yields 9,421 us slow and 21,847 us fast (42.67 fast chirps). Swapping radio and radio2 swaps the allocations automatically. The 0.3 ms reserve is not a sleep.

The calculator accepts board-specific allowances, but production scheduling uses the requested 600 us per switch plus 300 us per cycle. This is a nominal fast-switch allowance, not a worst-case bound. Diagnostics use the larger of 600 us and the observed maximum switch time; an overrun increases the warning estimate without automatically changing wire preambles or saved configuration. Recent V4 tests peaked at 836 us (827 us in the 4.6/0.3 ms run), and Indicator reached 8428 us: both can exceed the nominal allowance. The model preserves two slow-profile return opportunities and the existing 16-symbol fast-profile acquisition allowance. These are conservative policies, not a fitted success curve, and neither packet overlap nor arbitrary application stalls can be made safe by a finite preamble recommendation.

See the implementation and validation notes.

Schedule the second profile

Use UTC Unix timestamps (seconds):

set radioat2 910.5,500,8,5,rxtx,START[,PREAMBLE]
set tempradioat2 910.5,500,8,5,rxtx,START,END[,PREAMBLE]
get radioat2
get radioat2 1
get tempradioat2
get tempradioat2 1
del radioat2 1
del tempradioat2 all

Replace START, END and the optional PREAMBLE with numbers; omit the square brackets. Each schedule family has four slots. Times must be in the future and within 24 days. Overlapping temporary second-profile sessions are rejected. radioat2 changes the saved second profile when it starts; tempradioat2 restores the saved profile at its end. Pending schedules do not survive reboot.

Return to one profile

set radio2 off

This saves the disabled state and cancels all second-profile temporary activity and schedules.

set tempradio2 off

This ends temporary second-profile activity, cancels its temporary schedules and restores saved radio2. If the saved second profile is off, this returns to one profile. Packets/retries bound to an expired or changed session are discarded.

Power saving and diagnostics

Dual mode suspends RX power saving and MCU idle sleep so receive visits can run promptly. The saved RX power-saving setting returns when profile 2 is off. The scan uses normal receive, following the CAD/RX measurements, with the updated 4.6-symbol dwell on the slower channel, followed by the remaining fast-channel visit. It does not use CAD for scanning. The separate CAD check before an initial transmission still follows cad.

SX1262 dual-profile mode keeps the oscillator running in XOSC standby between visits, so each retune does not need to restart the TCXO. It restores the prior standby policy when returning to one profile, together with the saved RXPS setting. Radio reinitialization temporarily uses RC standby until the TCXO has been configured again. Other radio families retain their existing behavior. This does not disable the TCXO supply or its initial startup delay, and it is not conditional on 500 kHz bandwidth. Keeping the oscillator on uses additional power during the short standby intervals.

The requested 0.6 ms switch budget is a nominal scheduling allowance, not a forced settling delay or a measured worst-case bound. The earlier standalone keep-warm scan experiment averaged about 1.19 ms of overhead per hop (scan-cycle time minus both receive windows, divided by two). That experiment used a leaner receive path; it is not a measurement or guarantee of the production implementation. Measure the target board before shortening its timing margins or transmit preambles.

The production-path XIAO timing test measured 1.434 ms average / 1.467 ms maximum with warm standby, compared with 3.166 ms average using RC standby: about 1.732 ms saved per hop. It covered 12,000 retunes across SF7/8/9 at 500 kHz paired with SF7/62.5 kHz. These measurements include observing BUSY low, but exclude application/UI scheduling and are not a packet-delivery qualification or a guarantee for other boards, especially those using I/O expanders.

A same-image follow-up batching SF/BW/CR into one modulation command reduced warm switching from 1.444 ms to 1.158 ms average (batched maximum 1.198 ms), saving another 0.286 ms / 19.8%. RadioLib's modulation caches and LDRO calculation remain synchronized; frequency, preamble, packet guards, and RX restart are unchanged. A later HIL-only screening tested redundant standby/IRQ/buffer/packet setup and SPI transfer changes. Its fastest candidate measured 0.535 ms mean on XIAO but 8.203 ms on the Indicator, whose radio GPIOs go through an I2C expander. The validated production implementation now opts XIAO S3 WIO and Indicator LoRa into buffered 8 MHz SPI and a guarded fast-RX state machine. It skips redundant standby, IRQ mapping, buffer-base writes and modem queries only during an owned continuous RX-to-RX retune. Preamble/packet parameters (including the IQ workaround), stale-IRQ clearing, RX commands and BUSY waits remain. TX, CAD, sleep, reset, RXPS and failed commands revoke reuse; failed RX startup rolls back the profile. Sleep entry uses standby and wake restores the existing TCXO voltage/delay. Other variants do not opt in to faster SPI or the fast-RX state machine. See production and USB validation for current measurements, lifecycle tests and limitations. The Indicator result also shows that the nominal 0.6 ms allowance is not an upper bound for every board; its scheduling and preambles need board-specific qualification. Measured overruns raise the recommended preambles shown by the CLI without rewriting configured values.

Single-channel noise-floor calibration and RSSI interference comparison are suspended while scanning. Retries use the radio's preamble/header activity indicators. LR2021 extra-SF side detectors are suspended and restored as well.

get radio2.status reports the active second-profile mode, MeshCore RX/TX counts for each profile, switch count, switch failures, longest measured switch and both effective preambles. A long switch time or rising error count indicates that the chosen settings need investigation on that board.

get radio2.scan shows which profile goes first, the two idle receive-window lengths in microseconds, and both effective preambles. It reports off in single-profile mode.