ULS-DeCoNet Quick Reference Guide

Reference for developers and integrators of ULS-DeCoNet — the ULS Devices Connection Network protocol for UART and CAN.

ULSDC-PBDS041125 · version 1.0.0 · issued November 13, 2025
The numbered PDF is the controlled copy: download it from the portal.

Protocol Stack

Application Layer    │ Objects, Blitz Messages, Device Data
Connection Layer     │ Routing, Object Access, System Commands
Interface Layer      │ Network Management, Device Discovery
Framing Layer        │ UART: ESC/COBS  |  CAN: Multi-frame
Physical Layer       │ UART 115200+    |  CAN 1Mbps

Addressing

Component	Size	Range	Description
Device ID (DID)	6 bits	0-63	Local device address
Connection ID (CID)	2 bits	0-3	Interface identifier
CNRID	8 bits	0-255	Combined routing ID: `(CID<<6)\|DID`

Special Addresses:

0: Master device
63: Broadcast / Uninitialized
1-62: Regular devices

UART Framing Modes

Mode	Delimiter	CRC	Overhead	Best For
RAW	None	None	0%	Custom protocols
ESC	0x55 0x01/0x03	CRC-16	~15-25%	General purpose
ESC_SIMPLE	0x55 0x01/0x03	8-bit sum	~12-20%	Low-power
COBS	0x00	CRC-16	~0.4-2%	Binary data

Frame Examples

ESC Mode:

[0x55][0x01][DATA...][CRC_L][CRC_H][0x55][0x03]

COBS Mode:

[0x00][CODE][DATA...][CRC_L][CRC_H][0x00]

CAN Frame Structure

Single-Frame (≤10 bytes payload)

[CMD][DID][PAYLOAD(6 bytes)]

Multi-Frame (>10 bytes)

Frame N:   [CMD][DID][FRMCTL][PAYLOAD(5 bytes)]
Last Frame: FRMCTL = 0x80 | frame_number

Frame Control (FRMCTL):

Bit 7: End flag (1 = last frame)
Bits 6-0: Frame number (0-127)

IF Layer Commands

Code	Name	Description
0x00	SYS	System command
0x01	NM_HB	Heartbeat (1000ms interval)
0x02	NM_GET_STATUS	Get device status
0x03	NM_REQUEST_ID	Request ID allocation
0x04	NM_SET_ID	Assign device ID
0x05	NM_RESET_ID	Reset device ID
0x06	BLITZ	Sensor data message

Packet Structure:

[CMD][SRC_LID][PAYLOAD]

CN Layer Commands

Code	Name	Description
0x10	EXPLORER	Network discovery
0x11	ACK_EXPLORER	Discovery response
0x12	SYS	System operation
0x13	ACK_SYS	System response
0x14	GETOBJ	Read object
0x15	ACK_GETOBJ	Object data response
0x16	SETOBJ	Write object
0x17	ACK_SETOBJ	Write acknowledgment

Packet Structure:

[CMD][SRC_DID][HOP][ROUTE...][PAYLOAD]

HOP byte:
  Bits 7-4: Current hop index
  Bits 3-0: Route size

System Sub-Commands

Code	Name	Description
0	PING	Device ping
1	SETMODE	Set APP/LOADER mode
2	ERASE	Erase flash memory
3	WRITE	Write flash memory
4	SETSIGNATURE	Set firmware signature
5	SAVECFG	Save configuration

Result Codes:

0: UNDEFINED
1: OK
2: ERROR
3: WRONGKEY

Blitz Messages

Message Types

ID	Name	Size	Description
0x0010	XCG1_RAW	8B	Legacy ±30° measurement
0x0011	RAW_MEASURMENT	8B	±180° measurement
0x0012	POS_TX_FRAME	8B	3D position (cm)
0x0013	MRX	6B	Multi-receiver data
0x0014	DACS	8B	Continuous yaw
0x0020	GIMU	8B	Ground IMU data
0x0030	IMU_OVERRIDE	8B	Override IMU
0x0031	MAG_OVERRIDE	8B	Override magnetometer

Status Bits

Bit	Flag	Description
0	CARRIER_OK	IR signal present
1	SQ_OK	Signal quality OK
2	POS_OK	Position valid
3	VEL_OK	Velocity valid
4	GU_IMU_OK	Ground IMU OK
5	MRX_OK	MRX received
6	MRXDATA_OK	MRX data valid

Data Encoding

Angles (±180°):

int16_t = (degrees / 180.0) * 32767.0
degrees = (int16_t / 32767.0) * 180.0

Position/Distance (cm):

value_cm = int16_t or uint16_t
value_m = value_cm * 0.01

Object Permissions

Value	Name	Read	Write
0	READONLY	✓	✗
1	WRITEONLY	✗	✓
2	READWRITE	✓	✓
3	PROTECTED	✓	✓*
4	CONFIG	✓	✓*
5	SYSCONFIG	✓	✓*
6	ADMIN	✓	✓*

*Requires authorization

Network States

Device States

UNINITIALIZED (DID=63)
    ↓ Send REQUEST_ID
    ↓ Receive SET_ID
OK (DID assigned)
    ↓ Send HB every 1000ms
    ↓ Timeout 3000ms
ERROR

Common Operations

Device Discovery

1. Master sends CN_CMD_EXPLORER
2. Devices forward and respond with ACK_EXPLORER
3. Master builds topology map

Read Object

1. Send CN_CMD_GETOBJ with object ID
2. Receive CN_ACK_GETOBJ with data

Write Object

1. Send CN_CMD_SETOBJ with object ID and data
2. Receive CN_ACK_SETOBJ confirmation

Firmware Update

1. SETMODE → LOADER
2. ERASE flash region
3. WRITE firmware blocks (512 bytes each)
4. SETSIGNATURE with metadata
5. SAVECFG
6. SETMODE → APP

Timing Parameters

Parameter	Value	Description
HB_INTERVAL	1000 ms	Heartbeat send interval
DEVICE_TIMEOUT	3000 ms	Device disconnection timeout
REQUEST_ID_INTERVAL	100 ms	ID request interval
REQUEST_ID_RETRIES	5	Max ID request attempts
CAN_DEV_TIMEOUT	128 frames	CAN multi-frame timeout
CAN_POOL_SIZE	256 slots	CAN frame buffer pool

Performance Metrics

UART @ 115200 bps

Mode	Throughput	Latency
RAW	11.5 KB/s	~0 ms
ESC	9.6 KB/s	~0.17 ms
COBS	11.3 KB/s	~0.09 ms

CAN @ 1 Mbps

Message	Frames	Time	Throughput
10 bytes	1	108 µs	92.6 KB/s
256 bytes	52	5.6 ms	45.6 KB/s

Error Handling

UART

CRC errors → discard frame, increment counter
Framing errors → resync to next delimiter
Buffer overflow → flush and restart

CAN

Missing frames → timeout and cleanup
Pool overflow → emergency cleanup
Bus-Off → automatic recovery

Code Examples

Initialize Connection (UART)

ULSSerial serial(&rxFifo, &txFifo);
serial.mode(SERIAL_MODE_COBS);
ULSBusInterface interface("UART1", static_did);
interface.open();

Initialize Connection (CAN)

ULSBusConnectionCAN can(&hfdcan1, &device, 
                        &connections, "CAN1", 
                        static_did, cid);
can.setSpeed(1000000);
can.open();

Send Blitz Message

__uls_blitz_msg_rx_raw_measurmet msg;
msg.status = calc_status();
msg.counter = counter++;
msg.aX = (angle_x / 180.0) * 32767;
msg.aY = (angle_y / 180.0) * 32767;
msg.distance = distance_m * 100;

interface->ifSendBLITZ(
    ULS_BLITZ_MSG_ID_RX_RAW_MEASURMENT,
    (uint8_t*)&msg, sizeof(msg)
);

Receive Blitz Message

interface->ifclbkBlitzReceived = &onBlitz;

void onBlitz(ULSBusInterface *iface) {
    uint16_t msg_id = iface->ifRxPacket->blitz.msg_id;
    uint8_t *data = iface->ifRxPacket->blitz.data;
    
    switch(msg_id) {
        case ULS_BLITZ_MSG_ID_RX_RAW_MEASURMENT:
            process_measurement(data);
            break;
    }
}

Read Object

uint8_t route[] = {0x05};  // DID=5
connection->cnSendGetObject(route, 1, 0x0100);

// In callback
connection->cnclbkObjReceived = &onObjReceived;

System Command

uint8_t route[] = {0x05};
uint32_t key = _ULS_OPERATION_KEY;
connection->cnSendSysSetMode(route, 1, 
                            CN_SYS_MODE_LOADER);

Troubleshooting

Issue	Check	Solution
No communication	Baud rate, wiring	Match settings, check connections
CRC errors	Noise, cable quality	Add shielding, lower baud rate
Device timeout	HB interval	Check network connectivity
Pool overflow	Traffic load	Increase pool size, reduce rate
Missing frames	Bus load	Reduce message rate

Key Definitions

// Operation Key
#define _ULS_OPERATION_KEY 0x24041982

// Buffer Sizes
#define IF_PACKET_SIZE 1324
#define CN_CAN_POOL_SIZE 256
#define CN_CAN_DEV_SIZE 64

// Timeouts
#define IF_NM_DVICE_HB_TIMEOUT 3000
#define IF_NM_PING_HB_TIMEOUT 1000
#define IF_NM_REQUESTID_TIMEOUT 100

Document References

Overview: ULS-DeCoNet_Protocol_Overview.md
UART: ULS-DeCoNet_UART_Protocol.md
CAN: ULS-DeCoNet_CAN_Protocol.md
Blitz: ULS-DeCoNet_Blitz_Messages.md