mirror of
https://github.com/mikecarper/MeshCore.git
synced 2026-09-25 16:13:36 +00:00
mikecarper
091c8d8324
Skip redundant modulation writes during owned fast RX retunes when the last acknowledged SF/BW/CR/LDRO tuple matches. Invalidate that cache after ordinary setters, failed writes, and lifecycle changes. Include the remaining scan, preamble, settling, and memory-soak experiments, their collectors, validation notes, and original capture records. Preserve capture bytes across checkouts and keep private soak credentials local. Run lab collector and compiled contract tests in CI. Update the expectation, profile mapping, and result-buffer tests for the extended lab tools, and make the private WiFi override header optional for ordinary soak diagnostics. Validation: 145 host tests passed from the staged source snapshot. Clean heltec_v4_repeater and Xiao_S3_WIO_companion_radio_usb builds passed their RAM/flash gates. All 229 staged capture files retain their original bytes; all 75 local documentation links resolve in the clean snapshot.
139 lines
8.4 KiB
Markdown
139 lines
8.4 KiB
Markdown
# SF7/62.5 + SF8/500, fast switching and preamble 32
|
||
|
||
User-requested hardware validation, 2026-09-14. This is a finite HIL experiment,
|
||
not a production reliability guarantee. No production timing defaults or
|
||
automatic-preamble overrides are changed by this test.
|
||
|
||
## Fixture and method
|
||
|
||
- Heltec V4 receiver, USB serial `44:1B:F6:69:CF:98`, normal chip RX gain (0x94).
|
||
- RAK4631 `9AB3B64C641BA927`: stationary transmitter at 909.5 MHz, SF7/62.5 kHz.
|
||
- T1000-E/LR1110 `34A9141999729D5D`: stationary transmitter at 910.5 MHz, SF8/500 kHz.
|
||
- CR4/5, explicit header, CRC, 32-symbol preamble, synthetic 16-byte sequence-tagged
|
||
payloads. -9 dBm chip output. Only one transmitter sends at a time on host request.
|
||
- Each transmitter initializes its assigned settings once. RF-frequency and
|
||
modulation-command counters must remain unchanged for every TX call.
|
||
- 100 fixed-channel controls per profile before scanning. Require 100/100 on
|
||
both before making a scan-timing inference.
|
||
- Three scanner settings, 100 packets per profile per setting, randomized
|
||
interleaving and 10–180 ms arrival delays. A miss does not cause a retry,
|
||
retune, reset, or early end of the finite sample. The scan expectation expires
|
||
after 1000 ms, far longer than the test frame and randomized host delay.
|
||
|
||
| Case | Loop reserve (not a delay) | Slow visit | Fast visit |
|
||
| --- | ---: | ---: | ---: |
|
||
| 4.1-chirp floor | 0 ms | 8.397 ms | 23.171 ms |
|
||
| Spare time used for 5.1 slow chirps | 0 ms | 10.445 ms | 21.123 ms |
|
||
| Previous reserve comparison | 4 ms | 8.397 ms | 19.171 ms |
|
||
|
||
The 5.1 case reallocates 2.048 ms from the fast visit to the slow visit; it does
|
||
not increase the nominal cycle. The 4 ms reserve is omitted from the first two
|
||
cases. The theoretical switch allowance is 0.6 ms per hop; actual switching is
|
||
measured, never forced to equal that allowance. Changed SF/BW requires one
|
||
modulation command per hop; frequency-only cache-hit timings do not apply.
|
||
|
||
The scheduler uses the same asymmetric two-profile visit budget and the actual
|
||
production guarded `tuneProfile()` / fast RX implementation, but runs in a small
|
||
RAM-only HIL application, without the full production networking/UI load. All
|
||
retunes are single-pass, warm-XOSC, buffered 8 MHz SPI, zero added settling;
|
||
double frequency writes, detours and rollback experiments are off. Packet/busy
|
||
ownership guards are retained. Explicit 32 on both sides bypasses the historical
|
||
automatic SF8/500 88-symbol rule without removing it from production.
|
||
|
||
The selected radios already had disposable HIL firmware. Updates are
|
||
application-only: matching nRF52 SoftDevice IDs/address ranges and exact USB
|
||
serial/topology are checked. V4 partition metadata is read back and compared
|
||
before its application-only write. No bootloader, SoftDevice, settings backup,
|
||
gateway firmware or unrelated radio is changed. Prior images/captures remain.
|
||
|
||
## Results
|
||
|
||
Finished all 800 unique probes, 2026-09-15 00:04:54–00:11:19 UTC (September 14
|
||
local time). Both stationary controls passed 100/100. All three scans completed
|
||
their full 100-packet sample per profile. No scan achieved 200/200.
|
||
|
||
| Case | SF7/62.5 received | SF8/500 received | Total | Switch mean / max | Idle cycle mean / max |
|
||
| --- | ---: | ---: | ---: | ---: | ---: |
|
||
| 4.1 chirps, no loop reserve | 99/100 | 100/100 | 199/200 | 0.581 / 0.829 ms | 32.717 / 34.733 ms |
|
||
| 5.1 chirps, no loop reserve | 100/100 | 97/100 | 197/200 | 0.572 / 0.834 ms | 32.706 / 34.978 ms |
|
||
| 4.1 chirps, 4 ms loop reserve | 97/100 | 99/100 | 196/200 | 0.567 / 0.836 ms | 28.701 / 31.195 ms |
|
||
|
||
Switch timing includes every successful hop during each stage, including
|
||
post-reception hops. The RX-only five-second windows averaged 0.554 ms per hop.
|
||
The largest observed switch was 0.836 ms: 0.6 ms is a nominal allowance, **not a
|
||
measured worst-case bound**. Direction-specific timing is in the validated
|
||
capture. Idle-cycle samples exclude packet-held visits but still include USB
|
||
command/loop scheduling; their occasional roughly 2 ms overshoots are real.
|
||
|
||
Every scan hop issued exactly one RF-frequency and one modulation command,
|
||
with one optimized RX restart. There were zero added settling delays, double
|
||
passes, frequency repeats, RF retries, USB result replays, device errors,
|
||
retune failures, RX mode errors, cache errors or off-channel acceptances.
|
||
All eight missed packets were sequence-matched RX timeouts with the receiver
|
||
still in RX mode and no device error. Both transmitters acknowledged exactly
|
||
400 transmissions and zero frequency/modulation writes during every packet.
|
||
|
||
Successful scan packets had mean SNR approximately +12.0 to +12.1 dB on the
|
||
slow profile and +12.8 dB on the fast profile. Mean RSSI was approximately
|
||
-20.4 to -20.7 dBm and -18.5 to -18.9 dBm, respectively. These are strong-signal
|
||
bench results; the controls passed, but weak-signal performance and possible
|
||
strong-signal/front-end effects are not established by this test.
|
||
|
||
## What the extra chirp changes
|
||
|
||
An extra SF7/62.5 symbol is 2.048 ms, equivalent to **four SF8/500 symbols**.
|
||
Increasing the slow dwell from 4.1 to 5.1 preserves the full-sweep budget by
|
||
shortening the fast dwell, but increases the fast profile's uninterrupted
|
||
blind interval. With the nominal 0.6 ms hops, the 32-symbol fast preamble's
|
||
remaining time after the slow visit plus two hops falls from 6.787 to 4.739 ms
|
||
(13.26 to 9.26 fast symbols), before acquisition and scheduling overruns.
|
||
This is a timing-budget calculation, not an experimentally proven acquisition
|
||
threshold or a per-miss trace.
|
||
|
||
The observed 5.1 sample improved the slow result from 99 to 100, while the fast
|
||
result fell from 100 to 97. This is consistent with a dwell/acquisition tradeoff;
|
||
one finite sample per setting does not isolate the cause or establish a
|
||
statistically reliable ranking. Simply fitting a sweep inside a preamble does
|
||
not establish lossless acquisition. The 4 ms reserve is an allowance, not a
|
||
sleep; retaining it also did not produce a lossless result here.
|
||
|
||
Using genuine spare time above the 4.1 floor remains a reasonable policy to
|
||
investigate, but allocation must protect **both** profiles' acquisition/return
|
||
budgets and measured switching/scheduling overruns. Do not automatically spend
|
||
all of the reserve on longer slow visits, or treat the historic 88-symbol rule
|
||
as disproven by this nearly-lossless sample. No production defaults or warning
|
||
formula were changed by this hardware-test turn.
|
||
|
||
## Capture integrity, deployment and cleanup
|
||
|
||
- Raw capture: [profile_pair_sf8_32_results.json](../tools/hil/profile_pair_sf8_32_results.json),
|
||
SHA-256 `3472883ade89494b64657486efd1645a04b0a3bebfd0a2e31bbf914341ad792f`.
|
||
- Independent offline checks: [profile_pair_sf8_32_validated.json](../tools/hil/profile_pair_sf8_32_validated.json).
|
||
Checks all 800 unique sequences, 100/profile/phase, sender lifetime counts,
|
||
actual RX frequency/SF/BW/payload identity, command counts, policies and cleanup.
|
||
- [Manifest](../tools/hil/profile_pair_sf8_32_manifest.json) records source and image hashes.
|
||
Bundle SHA-256 `d6cb9ff36be109af8906eddbbe8a4657ca793d1351ec4bf50ebbd4909eed2bba`.
|
||
Local bundle is `out/pair-sf8-32-20260914`; remote capture remains under
|
||
`/home/mikec/hwtest/runs/pair-sf8-32-20260914`.
|
||
- Initial RAK USB reset returned EPROTO before any firmware write. The preserved
|
||
[pre-write record](../tools/hil/profile_pair_sf8_32_deployment-prewrite-usb.json)
|
||
has an empty writes list. Inspection confirmed the exact RAK serial/topology
|
||
in its documented CDC-only bootloader PID 0x002A. Deployment was revised to
|
||
accept that identity (and reset-time disconnect only after exact bootloader
|
||
re-enumeration); no permission check or board-identity check was bypassed.
|
||
The revision hash and all three successful application-only writes are saved
|
||
in the deployment records. No bootloader or SoftDevice was replaced.
|
||
- All three radios were rebooted and live-verified idle, with test firmware left
|
||
installed. ModemManager was restored active; gateway and host CLI services
|
||
remained active. The preexisting memory soak remains inactive. No unrelated
|
||
radio was flashed. Wrapper exit was zero.
|
||
- All three HIL firmware builds passed, run sequentially. The HIL host regression
|
||
suite passed **63/63 tests**, including the new plan and packet-policy tests.
|
||
Python compile checks and scoped `git diff --check` passed. No commit or push.
|
||
|
||
## Follow-up
|
||
|
||
The requested [4.6-chirp / 0.3 ms reserve follow-up](pair_4p6_300us_validation.md)
|
||
completed 197/200 scanning packets: slow 97/100, fast 100/100, after fresh
|
||
100/100 controls on both profiles. Its captures are separate from this run.
|