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14 ‐ RSPB Mortality Tracker

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gfo974 edited this page Jul 6, 2026 · 4 revisions

Overview

The RSPB tracker is a wildlife GPS/Satellite tracker designed for bird monitoring. It uses a nano-power architecture: the device spends most of its time completely powered off. An external timer chip (TPL5111) periodically wakes the tracker to perform a short operational cycle, then the device powers down again.

  TPL5111 Timer (every ~1h45)
         |
         v
  +-------------+     +----------------+     +------------------+     +-----------+
  |    BOOT     | --> | PRE-OPERATIONAL| --> |   OPERATIONAL    | --> | POWER OFF |
  | Check modulo|     | Check battery  |     | GNSS + TX cycle  |     | Wait next |
  | counter     |     | level          |     | (limited by      |     | TPL5111   |
  +------+------+     +-------+--------+     |  NTIME_SAT)      |     | wakeup    |
         |                    |               +--------+---------+     +-----------+
         |                    |                        |
         v                    v                        v
   Not our turn?       Battery critical?        TX limit reached?
   --> POWER OFF       --> POWER OFF            --> POWER OFF
       immediately         immediately              (session done)

Key Concept: Duty Cycling with TPL5111

The TPL5111 is an external nano-power timer that physically controls the power supply. When the tracker powers down, the TPL5111 keeps counting and will re-power the device after its configured interval (~1h45min).

To further reduce energy usage, not every wakeup results in an active cycle. The BOOT_COUNTER_MODULO parameter controls this:

 Wakeup 1     Wakeup 2     Wakeup 3     Wakeup 4     Wakeup 5
  (skip)       (skip)       (skip)      ACTIVE!        (skip)  ...
    |            |            |            |              |
    v            v            v            v              v
 increment    increment    increment    modulo=4       increment
 counter +    counter +    counter +    --> RUN!       counter +
 power off    power off    power off    GPS + TX       power off

                    With modulo=4 and 1h45 interval:
                    Active cycle every ~7 hours

Battery Modes

The tracker operates in three distinct modes depending on battery voltage. Each mode has different behavior to maximize device lifetime.

  Battery Level
  ============

  100% |########################################|
       |             NORMAL MODE                 |  Full operation:
       |          GPS fix + Sensor data          |  GNSS, Sensors, Satellite TX
       |         + Satellite transmission        |
       |                                         |
  LB%  |---- LB_THRESHOLD (default: 10%) -------|
       |           LOW BATTERY MODE              |  Reduced operation:
       |         Doppler TX only (no GPS)        |  Battery voltage only
       |         Fewer messages per session       |
       |                                         |
  LBP12|---- LB_CRITICAL_THRESH (default: 5%)   |
       |          CRITICAL MODE                  |  No operation:
       |       Immediate power off               |  Preserve battery for
       |       No TX, no GPS, nothing            |  solar recharge
   0%  |_________________________________________|

Mode 1: Normal Operation

When battery is above LB_THRESHOLD:

  WAKEUP
    |
    v
  +--------+     +-------+     +--------+     +--------+     +--------+
  | GNSS   | --> | Got   | --> | TX #1  | --> | TX #2  | --> | TX #3  | --> POWER OFF
  | acquire |     | fix!  |     | (GPS+  |     | (GPS+  |     | (GPS+  |
  | position|     | Stop  |     | sensor)|     | sensor)|     | sensor)|
  | (1 fix) |     | GNSS  |     |  60s   |     |  60s   |     |        |
  +----+----+     +-------+     +--------+     +--------+     +--------+
       |
       | No fix after timeout?
       v
    TX with "NO FIX" status --> POWER OFF

What happens:

  1. GNSS module powers on, acquires one satellite fix (position)
  2. With GNSS_SESSION_SINGLE_FIX=1, GNSS stops after the first fix (saves power)
  3. The tracker sends SHUTDOWN_NTIME_SAT satellite transmissions (default: 5)
  4. Each transmission contains GPS position + sensor data
  5. Transmissions are spaced by TR_NOM interval (default: 60 seconds)
  6. After the last transmission, the device powers down

NTIME_SAT vs NTRY_PER_MESSAGE: Both count radio transmissions. NTIME_SAT is the total TX budget per session. NTRY_PER_MESSAGE controls how many times the same data is repeated (burst) to increase reception probability. Example: NTIME_SAT=5, NTRY=2 → data A sent 2x, then data A sent 2x again (new TR_NOM interval), then data A sent 1x → shutdown after 5 total TX.

Parameters controlling Normal mode:

Parameter DTE Key Default RSPB Description
GNSS_SESSION_SINGLE_FIX GNP30 0 (off) 1 Stop GNSS after first fix
SHUTDOWN_NTIME_SAT PWP05 0 (off) 5 Total satellite TX before powerdown (includes NTRY repetitions)
TR_NOM ARP05 60s 60s Interval between TX messages
GNSS_COLD_ACQ_TIMEOUT GNP09 530s 180s Max time for cold GPS fix
GNSS_ACQ_TIMEOUT GNP05 120s 90s Max time for warm GPS fix
GNSS_DYN_MODEL GNP11 0 (portable) 6 (airborne) GPS motion model for birds
GNSS_HACCFILT_THR GNP21 5m 10m Accept fix with this accuracy
NTRY_PER_MESSAGE ARP19 0 0 Burst repetitions per data. 0 recommended = unlimited replay until the SHUTDOWN_NTIME_SAT powerdown (a finite N < NTIME_SAT stalls the session until SHUTDOWN_TIMER)
ARGOS_RX_EN ARP32 1 (on) 0 Satellite downlink — not implemented on SMD builds; keep 0

Mode 2: Low Battery

When battery drops below LB_THRESHOLD and LB_EN=1:

  WAKEUP
    |
    v
  +----------+     +----------+     +----------+
  | Doppler  | --> | Doppler  | --> | POWER    |
  | TX #1    |     | TX #2    |     | OFF      |
  | (battery |     | (battery |     |          |
  |  voltage)|     |  voltage)|     |          |
  |   90s    |     |          |     |          |
  +----------+     +----------+     +----------+

  NO GPS, NO SENSORS
  Just battery voltage in a small Doppler packet (3 bytes)
  Satellites use Doppler shift to estimate position

What happens:

  1. No GNSS module powered (saves significant energy)
  2. No sensor acquisition
  3. The tracker sends LB_SHUTDOWN_NTIME_SAT Doppler messages (default: 2)
  4. Each Doppler message contains only battery voltage (24 bits / 3 bytes)
  5. The Argos satellite system uses Doppler frequency shift to estimate position
  6. Messages are spaced by TR_LB interval (default: 90 seconds)
  7. After the last message, the device powers down

Parameters controlling Low Battery mode:

Parameter DTE Key Default RSPB Description
LB_EN LBP01 0 (off) 1 Enable low battery mode
LB_THRESHOLD LBP02 10% 10% Battery % to enter LB mode
LB_GNSS_EN LBP06 1 (on) 0 Disable GNSS in LB mode
LB_SHUTDOWN_NTIME_SAT LBP14 0 (off) 2 Number of Doppler TX before powerdown
TR_LB ARP06 240s 90s Interval between Doppler TX

Mode 3: Critical Battery

When battery SOC drops below LB_CRITICAL_THRESH:

  WAKEUP
    |
    v
  IMMEDIATE POWER OFF
  (no GPS, no TX, nothing)
  Wait for solar recharge

What happens:

  1. The device detects critically low battery at boot
  2. Immediately powers down without any operation
  3. The TPL5111 will keep waking the device periodically
  4. Once solar panels recharge the battery above critical threshold, the device will resume Low Battery or Normal mode

Exception: If a magnet is detected (reed switch engaged) while in critical battery state, the device enters configuration mode instead of powering off. This allows reconfiguring a depleted device via BLE without waiting for solar recharge.

Parameters controlling Critical mode:

Parameter DTE Key Default Description
LB_CRITICAL_THRESH LBP12 5% SOC percentage threshold for critical mode

Safety Net: Shutdown Timer

The SHUTDOWN_TIMER is an independent safety mechanism that runs in parallel with the NTIME_SAT counter. It prevents the device from staying awake indefinitely if something goes wrong (e.g., satellite TX keeps failing).

  WAKEUP
    |
    +---> Start SHUTDOWN_TIMER (600s = 10 minutes)
    |
    +---> Start normal operation (GPS + TX cycle)
    |
    |     Which triggers first?
    |     =======================
    |
    +---> NTIME_SAT reached (e.g., 3 TX done)  --> POWER OFF  (normal case)
    |
    +---> SHUTDOWN_TIMER expired (600s)          --> POWER OFF  (safety net)
Parameter DTE Key Default RSPB Description
SHUTDOWN_TIMER PWP01 0 (off) 600s Max seconds awake per cycle

Pseudo RTC (Timekeeping Without Battery Backup)

The TPL5111 architecture means the MCU loses all RAM state at each power-off, including the real-time clock. There is no battery-backed RTC crystal on the RSPB board. To maintain approximate time between wakeups, the firmware implements a pseudo RTC chain using a flash-persisted parameter.

How It Works

  Boot N                                       Boot N+1
  ======                                       ========

  Read LAST_KNOWN_RTC from flash               Read LAST_KNOWN_RTC from flash
  (e.g., 1708444800)                           (e.g., 1708451100)
       |                                            |
       v                                            v
  Add WAKEUP_PERIOD                            Add WAKEUP_PERIOD
  (+ 3600 seconds)                             (+ 3600 seconds)
       |                                            |
       v                                            v
  rtc->settime(1708451100)                     rtc->settime(1708457400)
  "Approximate time set"                       "Approximate time set"
       |                                            |
       v                                            v
  ... GNSS fix acquired ...                    ... GNSS fix acquired ...
  Exact time from satellite!                   Exact time from satellite!
       |                                            |
       v                                            v
  Save LAST_KNOWN_RTC to flash                 Save LAST_KNOWN_RTC to flash
  (real timestamp from GNSS)                   (real timestamp from GNSS)

Chain Initialization

The pseudo RTC chain needs a starting value. There are two ways to seed it:

  1. First GNSS fix: When the device gets its first GPS fix, LAST_KNOWN_RTC is automatically saved to flash during the power-off phase. Subsequent boots use this as the base.

  2. Manual seed via RTCW command: Before deployment, send the current Unix timestamp via DTE:

    $RTCW#00A;1708444800\r

    This sets the RTC immediately and also saves LAST_KNOWN_RTC to flash, seeding the chain without needing a GNSS fix first.

Accuracy

The pseudo RTC drifts by the difference between the configured WAKEUP_PERIOD and the actual TPL5111 timer interval. Typical drift is a few seconds per cycle. Each successful GNSS fix corrects the drift completely.

If the device fails to get a GNSS fix for several cycles, the time will gradually drift but remain usable for pass prediction and timestamping.

Related Parameters

Parameter DTE Key Description
LAST_KNOWN_RTC PWP06 Flash-persisted Unix timestamp. Updated on GNSS fix, PMU powerdown, and RTCW. Available on all boards.
WAKEUP_PERIOD PWP04 TPL5111 period in seconds (~3600s, build_rspb.sh default). Added to LAST_KNOWN_RTC at boot. RSPB only.
RTC_CURRENT_TIME SYT01 Live RTC value readable via STATR.

Note: LAST_KNOWN_RTC is now persisted on all board variants (not just RSPB). On LinkIt V4 boards (no TPL5111), the last known RTC is restored directly at boot without adding a wakeup period. This enables MGA-ANO GNSS assistance data validation and faster time-to-first-fix after reset/crash.

Reading Current RTC

To check the current RTC time:

$STATR#005;SYT01\r
$O;STATR#010;SYT01=1708451100\r

Complete Session Timeline

Normal mode example (RSPB deployment config):

  Time
   |
   |  T+0s     TPL5111 wakes device
   |            Boot, check modulo counter (is it our turn?)
   |            --> YES (counter % 4 == 0)
   |
   |  T+0.1s   Pre-operational: check battery
   |            --> Battery OK (Normal mode)
   |
   |  T+1s     GNSS module powered on
   |            Searching for satellites...
   |
   |  T+45s    First GPS fix acquired! (typical TTFF)
   |            GNSS module powered off (GNSS_SESSION_SINGLE_FIX=1)
   |
   |  T+46s    Satellite TX #1: GPS position + sensor data
   |
   |  T+106s   Satellite TX #2: GPS position + sensor data  (+60s TR_NOM)
   |
   |  T+166s   Satellite TX #3: GPS position + sensor data  (+60s TR_NOM)
   |            SHUTDOWN_NTIME_SAT reached (3/3)
   |            --> POWER OFF
   |
   |  T+166s   Total awake time: ~2.8 minutes
   |            Device sleeps until next TPL5111 wakeup (~7h later)
   |
   v

Low battery mode example:

  Time
   |
   |  T+0s     TPL5111 wakes device
   |            Boot, check modulo counter --> YES
   |
   |  T+0.1s   Pre-operational: check battery
   |            --> Battery LOW (Low Battery mode)
   |
   |  T+1s     Doppler TX #1: battery voltage (3 bytes)
   |            No GPS, no sensors
   |
   |  T+91s    Doppler TX #2: battery voltage    (+90s TR_LB)
   |            LB_SHUTDOWN_NTIME_SAT reached (2/2)
   |            --> POWER OFF
   |
   |  T+91s    Total awake time: ~1.5 minutes
   |
   v

All RSPB Parameters Reference

Power Management (TPL5111)

Parameter DTE Key Type Range Default RSPB Description
SHUTDOWN_TIMER PWP01 UINT 0-86400 0 600 Safety timeout (seconds). Forces powerdown if session exceeds this. 0=disabled.
BOOT_COUNTER PWP02 UINT - 0 - Read-only. Current boot count since last active cycle.
BOOT_COUNTER_MODULO PWP03 UINT 2-1000 2 4 Run active cycle every N wakeups. Higher = less frequent = more battery savings.
WAKEUP_PERIOD PWP04 UINT - 3600 - Writable (PWP04); compiled default via build_rspb.sh. TPL5111 wakeup period in seconds (~1h = 3600s); must match the resistor.
SHUTDOWN_NTIME_SAT PWP05 UINT 0-65535 0 3 Number of satellite TX messages per normal session before powerdown. 0=disabled.

GNSS (GPS)

Parameter DTE Key Type Range Default RSPB Description
GNSS_EN GNP01 BOOL 0/1 1 1 Enable GNSS module.
GNSS_ACQ_TIMEOUT GNP05 UINT 10-600 120 90 Warm/hot start timeout (seconds).
GNSS_COLD_ACQ_TIMEOUT GNP09 UINT 10-600 530 180 Cold start timeout (seconds). First fix or no backup battery.
GNSS_DYN_MODEL GNP11 ENUM 0-10 0 6 Motion dynamics model. 0=Portable, 6=Airborne 1G (birds).
GNSS_HACCFILT_THR GNP21 UINT 0+ 5 10 Horizontal accuracy filter (meters). Accept fix if hAcc < this value.
GNSS_MIN_NUM_FIXES GNP22 UINT 1+ 1 1 Consecutive valid fixes required before accepting.
GNSS_SESSION_SINGLE_FIX GNP30 BOOL 0/1 0 1 Stop GNSS after first successful fix in session. Saves battery.

Argos Satellite TX

Parameter DTE Key Type Range Default RSPB Description
TR_NOM ARP05 UINT 30-1200 60 60 Normal mode: interval between TX messages (seconds).
NTRY_PER_MESSAGE ARP19 UINT 0-86400 0 0 Number of times each message is repeated on air (0 = unlimited replay in LEGACY/DUTY_CYCLE/PASS_PREDICTION). RSPB recommended: 0 — replay until the SHUTDOWN_NTIME_SAT powerdown fires. ⚠️ A finite N below SHUTDOWN_NTIME_SAT (e.g. 3 < 5) goes inert before the TX-count powerdown, so the session idles until SHUTDOWN_TIMER; if a finite N is needed, keep N ≥ SHUTDOWN_NTIME_SAT.
ARGOS_RX_EN ARP32 BOOL 0/1 1 0 Satellite downlink (RX) — not implemented on SMD builds (RX service never started); keep 0.

First-message gate exemption. Unlike the turtle/LinkIt builds, RSPB is exempt from the "no TX until a valid GPS fix corrects the clock" gate: a boot-modulo session that fails to fix GPS still transmits its empty (0xFF) position + mortality/sensor packet (alive signal). The gate is compile-time #ifndef BOARD_RSPB.

Low Battery Mode

Parameter DTE Key Type Range Default RSPB Description
LB_EN LBP01 BOOL 0/1 0 1 Enable low battery mode. When battery < threshold, switch to LB behavior.
LB_THRESHOLD LBP02 UINT 0-100 10 10 Battery percentage to enter Low Battery mode.
LB_GNSS_EN LBP06 BOOL 0/1 1 0 Enable GNSS in LB mode. 0 = Doppler-only (no GPS position).
LB_SHUTDOWN_NTIME_SAT LBP14 UINT 0-65535 0 2 Number of Doppler TX per LB session before powerdown. 0=disabled.
TR_LB ARP06 UINT 30-1200 240 90 LB mode: interval between Doppler TX (seconds).
LB_CRITICAL_THRESH LBP12 UINT 0-100 5 5 Battery SOC (%) for critical mode. Below this = immediate poweroff.

Underwater / Surface Detection

Parameter DTE Key Type Range Default RSPB Description
UNDERWATER_EN UNP01 BOOL 0/1 0 0 Underwater detection. Disabled for aerial birds.
DRY_TIME_BEFORE_TX UNP02 UINT 0+ 1 0 Seconds at surface before TX allowed. 0 = TX immediately.

LEDs

Parameter DTE Key Type Range Default RSPB Description
LED_MODE LDP01 ENUM 0-3 1 0 Status LED. 0=OFF, 1=24h mode. Disabled on birds (invisible + wastes energy).
EXT_LED_MODE LDP02 ENUM 0-3 3 0 External LED. 0=OFF. Disabled on birds.

RSPB LED Behavior (independent of LED_MODE, always active)

These LED patterns fire regardless of the LED_MODE setting — they are critical feedback signals:

Moment LED Pattern Color Duration Description
Boot modulo skip Flash Yellow 300ms Device alive but not its turn to run. Powers off after.
Boot active cycle Solid White ~1s Normal boot, proceeding to operational cycle
Post-OTA reboot Flashing fast Green 3s Firmware update applied successfully after reboot
OTA BLE transfer Alternating Blue/White During transfer Firmware upload via BLE in progress
OTA CRC verified Solid Green 1.5s Upload OK, device will reset to apply firmware
OTA CRC failed Flashing Red Until next state Upload corrupted, transfer aborted
Battery critical Solid Yellow Until powerdown SOC below critical threshold, immediate powerdown

Note: For deployed RSPB trackers, LED_MODE=0 (OFF) is recommended to save battery and avoid disturbing the bird. The LED patterns above are brief (<3s) and only occur during boot or OTA — no LED activity during normal GPS/TX cycles. Surface/dive LEDs (green/blue flash) only apply to underwater-enabled trackers (LinkIt V4 UW), not RSPB.

Mortality Detection

Requires ENABLE_MORTALITY_SENSOR=1 (auto-enabled on RSPB). Combines AXL activity, body temperature, and GPS stationarity to compute a mortality confidence percentage (0-100%).

WARNING: Mortality detection requires AXL (AXP01=1), Thermistor (THP01=1), and GNSS (GNP01=1) to be enabled. If any sensor is disabled, the algorithm works with partial data only (biased toward ALIVE).

Parameter DTE Key Type Range Default RSPB Description
MORTALITY_ENABLE MTP01 BOOL 0/1 0 1 Enable mortality detection.
MORTALITY_ACTIVITY_THRESH MTP02 UINT 0-255 10 10 Activity score below which = immobile.
MORTALITY_TEMP_THRESH MTP03 FLOAT 0-60 25.0 25.0 Body temp below which = hypothermic (°C). Live bird ~40°C.
MORTALITY_GPS_DISTANCE_THRESH MTP04 UINT 0-10000 50 50 GPS movement below which = stationary (meters).
MORTALITY_CONFIRM_DAYS MTP05 UINT 1-30 3 3 Days of high confidence before CONFIRMED.
MORTALITY_DUTY_CYCLE_MODULO MTP06 UINT 0-100 0 6 New BOOT_COUNTER_MODULO when confirmed. 0=never modify.
MORTALITY_ORIGINAL_MODULO MTP07 UINT - 0 - Backup of original modulo (auto, read-only).

Scoring Algorithm

Each active session computes a session score (0-100) from three independent indicators:

Indicator Points Condition
Immobility 40 pts AXL activity < MORTALITY_ACTIVITY_THRESH (default 10)
Hypothermia 30 pts Thermistor temp < MORTALITY_TEMP_THRESH (default 25°C)
Stationarity 30 pts GPS moved < MORTALITY_GPS_DISTANCE_THRESH (default 50m) AND speed < 0.1 m/s

Confidence is computed as an exponential moving average:

confidence = (old_confidence * 7 + session_score * 3) / 10

70% weight on history, 30% on current session. This smooths out single bad readings.

Status State Machine

                    confidence >= 50%
    ALIVE ─────────────────────────────> SUSPECTED
      ^                                      |
      |           confidence < 50%           |
      +──────────────────────────────────────+
      |                                      |
      |     consecutive_days >= CONFIRM_DAYS |
      |                                      v
      +──────────────────────────── CONFIRMED
              bird shows life again

Daily evaluation (once per UTC calendar day):

  • If confidence >= 80% → increment consecutive_days
  • Otherwise → decrement consecutive_days (floor at 0)
  • If consecutive_days >= MORTALITY_CONFIRM_DAYS (default 3) → status = CONFIRMED

Duty Cycle Adaptation on Mortality

When mortality is CONFIRMED and MORTALITY_DUTY_CYCLE_MODULO > 0 (RSPB only):

  1. Save current BOOT_COUNTER_MODULO to MORTALITY_ORIGINAL_MODULO
  2. Set BOOT_COUNTER_MODULO = MORTALITY_DUTY_CYCLE_MODULO (e.g., 6)
  3. Device wakes less frequently → saves battery on dead bird

If the bird recovers (status returns to ALIVE):

  1. Restore BOOT_COUNTER_MODULO from MORTALITY_ORIGINAL_MODULO
  2. Clear MORTALITY_ORIGINAL_MODULO to 0

State Persistence (FsLog)

Mortality state (confidence, consecutive_days, status, last positions) is persisted to flash via a dedicated FsLog partition ("MORTALITY", 64KB). On each evaluation, a MortalityLogEntry is written. On boot, the last entry is read to restore state across TPL5111 power cycles.

This ensures the confirmation counter survives the complete power-off between wakeups.

Sensor Input Requirements

The service listens to peer events from:

  • AXL sensor → caches activity level (port[4])
  • Thermistor → caches body temperature
  • GNSS → caches position + speed

Evaluation triggers when GPS data is available AND at least one other sensor has reported. If a sensor is disabled, its indicator scores 0 (biased toward ALIVE). A dead bird will eventually be detected across subsequent sessions even with partial data.

Mortality Log

The service writes a MortalityLogEntry to mortality.log on each evaluation, readable via $DUMPD:

Field Type Description
confidence uint8 Current confidence (0-100%)
consecutive_days uint8 Days with high confidence
status uint8 0=ALIVE, 1=SUSPECTED, 2=CONFIRMED
last_activity uint8 Last AXL activity reading (0-255)
last_body_temp uint16 Last thermistor reading (raw)
last_lat double Last GPS latitude
last_lon double Last GPS longitude
last_eval_epoch uint32 Epoch of last daily evaluation

Safety Guarantees

  1. Compile-time: ENABLE_MORTALITY_SENSOR=OFF (default) → zero code on non-RSPB boards
  2. Runtime: MORTALITY_ENABLE=false (default) → service disabled, zero impact
  3. Duty cycle: MORTALITY_DUTY_CYCLE_MODULO=0 (default) → never touches duty cycle

RSPB Satellite Messages:

Three dedicated RSPB packet types (see Satellite Message Format for full decoding):

Type Name Modulation Bits When Used
4 (100) RSPB Long LDA2 192 (181 data + 3 reserved + 8 CRC) Normal mode with GPS fix
5 (101) RSPB Short LDK 122 Normal mode, compact (configurable via RSP01)
6 (110) RSPB Doppler VLDA4 24 Low battery / no GPS — bird status only

RSPB Long (with GPS, 192-bit LDA2 frame):

[Type 3b][Time 16b][GPS 51b][Battery 8b][Pressure 29b][Thermistor 14b][AXL X 15b][AXL Y 15b][AXL Z 15b][Activity 8b][Mortality% 7b][reserved 3b][CRC8 8b]
  3 + 16 + 51 + 8 + 29 + 14 + 15 + 15 + 15 + 8 + 7 + 3 + 8 = 192 bits (24 bytes)

The CRC8 covers bits 0..183. See 11 — Satellite Communication § F.2 Error correction & CRC for the algorithm.

RSPB Short (with GPS, 122 bits):

[Type 3b][Time 16b][GPS 51b][Battery 8b][Pressure 15b][Thermistor 14b][Activity 8b][Mortality% 7b]

RSPB Doppler (no GPS):

[Type 3b = 110][Battery SOC 7b][Activity 7b][Mortality% 7b] = 24 bits

Mortality confidence (7 bits, 0-100%) is always transmitted in all three packet types when the sensor is enabled, regardless of status — this allows satellite operators to observe the confidence trend.

Note on Low Battery Doppler: Without GPS, the mortality algorithm can only use activity + temperature (max ~70% confidence). The RSPB Doppler still sends the current confidence and activity so operators can see the bird's status remotely.

Note: AXL X/Y/Z axes (15 bits each) are included in RSPB Long for orientation analysis. AXL temperature is dropped. The activity score (8 bits) is included in both Long and Short packets.

Device Identity

Parameter DTE Key Type Default RSPB Description
PROFILE_NAME IDP11 TEXT FACTORY RSPB_DEPLOY_V1 Human-readable deployment profile name.

How to Configure a Device

Parameters are sent via BLE (Bluetooth) or USB using DTE commands. Each command starts with $PARMW# followed by the hex-encoded length of the payload, then a semicolon, then key=value pairs separated by commas.

RSPB Deployment Commands

Send these commands one by one via BLE (LinkIt app) or USB terminal:

 GNSS timeouts (faster, save battery on GPS failure)
$PARMW#00E;GNP09=180,GNP05=90\r

 Safety shutdown timer (10 minutes max per cycle)
$PARMW#00A;PWP01=600\r

 Duty cycle: active every 4th wakeup (~7 hours)
$PARMW#009;PWP03=4\r

 GNSS for bird flight (airborne model, relaxed accuracy)
$PARMW#015;GNP11=6,GNP21=10,GNP22=1\r

 Argos TX: no RX, 3 repetitions, no surface wait
$PARMW#016;ARP32=0,ARP19=3,UNP02=0\r

 Disable underwater detection
$PARMW#009;UNP01=0\r

 LEDs off (invisible on bird, save energy)
$PARMW#00E;LDP01=0,LDP02=0\r

 Session shutdown: 3 TX then powerdown, no GNSS re-acquisition
$PARMW#013;PWP05=3,GNP30=1\r

 Low battery: enable, no GPS, 2 Doppler TX, 90s interval
$PARMW#01C;LBP01=1,LBP06=0,LBP14=2,ARP06=90\r

 Profile name
$PARMW#015;IDP11=RSPB_DEPLOY_V1\r

Reading Parameters

To verify a parameter was set correctly:

$PARMR#005;PWP05\r

Response: $O;PARMR#007;PWP05=3\r

To read all parameters at once:

$PARMR#000;\r

Pre-Deployment Sensor Calibration

Perform these steps before attaching the tracker to the bird. Device must be in Configuration mode (BLE connected).

Step 1: Power on sensors

$PWRON#001;2\r

Step 2: Accelerometer auto-calibrate

Place device flat on a level surface, then:

$SCALW#005;0,3,0\r         # Auto-calibrate (measures 200 samples, ~3 seconds)

Verify:

$SCALR#003;0,1\r            # X calibrated → should be ~0.00g
$SCALR#003;0,2\r            # Y calibrated → should be ~0.00g
$SCALR#003;0,3\r            # Z calibrated → should be ~1.00g
$SCALW#005;0,6,0\r          # Save to flash

Pass criteria: X ≈ 0.00g, Y ≈ 0.00g, Z ≈ 1.00g (±0.05g)

Step 3: Pressure sea level

Look up current sea level pressure from a nearby weather station (hPa):

$SCALW#00D;1,0,1013.250000\r    # Set sea level pressure
$SCALR#003;1,0\r                 # Verify → 1013.250000

Step 4: Thermistor calibrate

Place device at a known temperature (e.g., next to a reference thermometer showing 23.5°C):

$SCALW#009;7,1,23.5\r       # Calibrate at 23.5°C (firmware measures 10 samples)
$SCALR#003;7,0\r             # Read offset → e.g., -1.2 (sensor was reading 1.2° too high)

Pass criteria: $SENSR#002;16,1\r → thermistor_temp ≈ reference temp (±0.5°C)

Step 5: Final verification

$SENSR#004;255,10\r

Check in response:

  • Battery: 3200-4200 mV, SOC 0-100%
  • Pressure: ~1013 hPa
  • Accel: X≈0, Y≈0, Z≈1
  • Thermistor: ≈ reference temperature
  • sensor_status (field 19): bits 0-4 set (≥ 0x1F)

RSPB Power Management

The RSPB board has specific power rail behavior distinct from LinkIt V4:

  • SENSORS_PWR_PIN is always ON at boot. The I2C pull-ups (R21, R24) are connected to the DCDC_3V3 rail controlled by this pin — cutting it would disable I2C communication with all sensors. (FIXME: future HW revision should route pull-ups to an always-on rail.)
  • POWER_CONTROL_PIN controls the main board power rail (SMD, sensors, peripherals). During deep idle (enter_deep_idle() in nrf_pmu.cpp), this pin is driven LOW to cut the rail. On wake (exit_deep_idle()), it is restored HIGH. This provides the lowest quiescent current between TPL5111 wakeups.
  • VPA_EN (SMD voltage power amplifier): driven LOW when the SMD is powered off to prevent leakage; released to high-impedance when the SMD is powered on so the PA supply operates normally.
  • Deep idle (enter_deep_idle() / exit_deep_idle() in nrf_pmu.cpp): cuts the POWER_CONTROL_PIN rail, puts unused GPIOs in safe state, and enters System OFF. On TPL5111 wakeup, exit_deep_idle() restores the rail before any peripheral access.

Estimated Energy Budget (RSPB Deployment)

Phase Duration Current Energy per cycle
Boot + modulo check (skip) ~50ms 5 mA ~0.07 uAh
Boot + pre-operational ~0.2s 5 mA ~0.3 uAh
GNSS acquisition (typical) ~45s 25 mA ~312 uAh
GNSS acquisition (worst: cold) 180s 25 mA ~1250 uAh
Satellite TX (x3, 60s interval) ~180s 15 mA avg ~750 uAh
Total per active cycle (typical) ~3 min - ~1.1 mAh
Total per active cycle (worst) ~6 min - ~2.3 mAh

With modulo=4 (one active cycle per ~7h): ~3-8 mAh per day NCR18650 battery (3400 mAh): theoretical ~400-1000 days without solar. With solar panels: effectively indefinite in good conditions.

Troubleshooting

Device not transmitting

  • Check SHUTDOWN_NTIME_SAT (PWP05) is not 0 — if 0, only SHUTDOWN_TIMER controls session end
  • Check GNSS_EN (GNP01) is 1
  • Check ARGOS_RX_EN (ARP32) — if 1, device spends 15min listening before TX

Device transmitting but no GPS position

  • Check GNSS timeouts: GNP09 (cold) and GNP05 (warm) may be too short
  • Check GNSS_HACCFILT_THR (GNP21) — if too low, fixes are rejected
  • Check GNSS_DYN_MODEL (GNP11) — wrong model can prevent lock

Battery draining too fast

  • Increase BOOT_COUNTER_MODULO (PWP03) for less frequent cycles
  • Reduce SHUTDOWN_NTIME_SAT (PWP05) for fewer TX per session
  • Ensure ARGOS_RX_EN (ARP32) is 0
  • Ensure LEDs are off: LDP01=0, LDP02=0
  • Reduce GNSS_COLD_ACQ_TIMEOUT (GNP09) to fail faster on bad GPS conditions

Low battery mode not activating

  • Check LB_EN (LBP01) is 1
  • Check LB_THRESHOLD (LBP02) — battery % must be below this value

Device stuck (never powers down)

  • SHUTDOWN_TIMER (PWP01) should be > 0 as a safety net
  • Recommended: 600s (10 minutes)

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