SPP's service layer. Provides the packet lifecycle infrastructure (databank, pub/sub, logging) and the sensor/logging drivers (BMP390, ICM20948, datalogger). All services share a common registration interface defined in service.h.

Every service describes itself with a static SPP_ServiceDesc_t:

typedef struct {
    const char   *p_name;   // Human-readable name for logging
    uint16_t      apid;     // Unique Application Process ID
    size_t        ctxSize;  // sizeof(service-private context struct)

    SPP_RetVal_t (*init)  (void *ctx, const void *cfg);
    SPP_RetVal_t (*start) (void *ctx);
    SPP_RetVal_t (*stop)  (void *ctx);
    SPP_RetVal_t (*deinit)(void *ctx);
} SPP_ServiceDesc_t;

Registration pattern in app_main():

static BMP390_ServiceCtx_t  s_bmpCtx;
static BMP390_ServiceCfg_t  s_bmpCfg = { .spiDevIdx = 1U, .intPin = 5U };

SPP_SERVICES_register(&g_bmp390ServiceDesc, &s_bmpCtx, &s_bmpCfg);
SPP_SERVICES_initAll();
SPP_SERVICES_startAll();

The registry calls init and start on each service in registration order. stop and deinit are called in reverse order on shutdown. No memory is allocated by the registry — all context buffers are caller-managed.

ISR (sets drdyFlag)
  │
  └─► superloop detects flag
        │
        └─► ServiceTask()
              │
              ├─ SPP_SERVICES_DATABANK_getPacket()
              ├─ SPP_SERVICES_DATABANK_packetData(pkt, apid, seq, data, len)
              │     fills headers, copies payload, computes CRC-16
              └─ SPP_SERVICES_PUBSUB_publish(pkt)
                    │
                    ├─► subscriber A (SD card logger)
                    ├─► subscriber B (antenna encoder)
                    └─► SPP_SERVICES_DATABANK_returnPacket(pkt)  ← automatic

Sensor services are producers only — they do not know who consumes their packets. Consumers register as subscribers at startup.

// Subscribe to a specific APID
SPP_SERVICES_PUBSUB_subscribe(K_BMP_SERVICE_APID, myHandler, &myCtx);

// Subscribe to all packets (sensor + log messages)
SPP_SERVICES_PUBSUB_subscribe(K_SPP_APID_ALL, sdLogHandler, &s_logger);

// Publish — dispatches to subscribers, then auto-returns packet to databank
SPP_SERVICES_PUBSUB_publish(p_pkt);

1. Create services/myservice/myservice.h and myservice.c
2. Implement init, start, stop, deinit callbacks
3. Define a ServiceTask() that calls getPacket() → packetData() → publish()
4. Declare const SPP_ServiceDesc_t g_myServiceDesc = { ... }
5. Add services/myservice/myservice.c to CMakeLists.txt
6. In app_main(): call SPP_SERVICES_register() before SPP_SERVICES_initAll()