The Scribe (Role 4) is the hive’s memory keeper — “its only job is to save data to its internal memory and recall it from shared memory if asked.” It runs on the M5Capsule, whose 8 MB flash and oversized 64 KB NVS partition make it the natural store for hive shared memory and role bundles.

The Redis variant (M5Capsule_Hive_Scribe_Redis) keeps every Scribe behavior and adds a RESP2-compatible TCP server so a laptop redis-cli — or any Redis client library — can read and write the same NVS-backed store the Scribe already manages.

Why Redis on a microcontroller

The hive already has a key-value substrate (KV_GET/KV_PUT), but it only speaks the MagNET wire protocol. Wrapping the same store in RESP2 means standard tooling just works: redis-cli, client libraries, dashboards. It turns the Scribe into something a laptop or another service can inspect and script without learning the hive protocol.

Wire format

RESP2. Both inline (PING\r\n) and array (*1\r\n$4\r\nPING\r\n) forms are accepted, so telnet and standard clients are equally happy. Frames cap at 16 KB; up to 4 concurrent clients (per-client task pattern, mirroring the hive ruler).

Commands implemented 

  PING [msg]      ECHO msg        QUIT            SELECT 0
AUTH pw (stub)  CLIENT ...       COMMAND [...]   INFO [section]
SET k v         GET k           DEL k [k...]    EXISTS k [k...]
TYPE k          KEYS pat        DBSIZE          FLUSHDB / FLUSHALL
LPUSH k v...    RPUSH k v...     LPOP k          RPOP k
LLEN k          LINDEX k idx     LRANGE k a b    (negative idx ok)

Unknown commands return -ERR unknown command 'X'. A list command on a string key (or vice versa) returns -WRONGTYPE.

Storage limits (NVS backend, v1)

Limit Value
User key length 14 chars
String value 1024 bytes
List total per key 4 KB
List entries per key 64
List entry length 1024 bytes
Concurrent clients 4

A future SD-FAT backend lifts each of these by roughly 1000×.

Configuration profiles 

  0 redis-profile!   →  local    bind=127.0.0.1   port=6379
1 redis-profile!   →  lan      bind=0.0.0.0     port=6379   (default)
2 redis-profile!   →  quiet    bind=0.0.0.0     port=16379
3 redis-profile!   →  custom   (preserved across reboots)

redis-bind <addr> and N redis-port switch the active profile to custom automatically. Profiles and overrides persist in NVS namespace scribe_redis.

Forth surface

Word Effect
redis-on Start the listener on the active config
redis-off Stop, close clients, clear redis:status
redis-status State + bind/port + clients + command counter
redis-profile Print active profile
N redis-profile! Apply preset 0–3 and persist
redis-bind Prompt for bind addr (→ custom)
N redis-port Set port (→ custom)
redis-flush FLUSHDB the local store
redis-do On-device client — prompt for a command, send to localhost, print reply

Built-in client — redis-do

redis-do connects to 127.0.0.1:<active-port> from the Capsule itself, so you can verify the loopback path without a laptop:

  redis> SET foo bar
+OK
redis> LPUSH log first second
(integer) 2
redis> LRANGE log 0 -1
1) "second"
2) "first"

Hive integration — the Dial indicator dot

While the server is up and the Scribe is joined, a 5 s heartbeat publishes redis:status = <self-id>:<port>:<clients> to the hive KV table. The Dial reads that key and lights a small orange dot (next to the purple MQTT-bridge dot), so you can confirm the server is reachable from across the room. The dot goes dark when redis-off clears the value.

Security model — v1

The IMU sidecar

The Redis-variant Capsule also carries a Bosch BMI270 6-DoF IMU on the internal I2C bus (SDA = G8, SCL = G40, addr 0x69). The craw_imu component samples at 50 Hz, runs a 6-DoF Madgwick AHRS, and serves fused orientation + raw accel/gyro at GET /api/v1/sensor/imu — the real-hardware swap for a simulated stream in the d3-spatial “airplane” dataspace.

The on-device RESP2 server design references the ESP32RedisClient project — github.com/DankJugal/ESP32RedisClient — as prior art for speaking Redis to/from ESP32-class hardware. MagNET’s twist is the server side, backed by NVS and bridged into the hive’s shared-memory model.

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Last updated 31 May 2026, 01:22 -0700 . history