Arduino UWB Positioning

UWB real-time location system (RTLS) firmware for 4 anchors x 12 tags using multicast Two-Way Ranging (TWR) sessions.

Hardware

Device	Board	UWB Module	Role
Anchor	Arduino Portenta C33 + UWB Shield	Truesense DCU150 (SR150)	Controller (one-to-many)
Tag	Arduino Stella	Truesense DCU040 (nRF52840)	Responder (controlee)

Sketches

File	Description
UWB_MulticastAnchor.ino	Anchor firmware — runs 2 multicast sessions (6 tags each), prints range measurements to Serial
UWB_MulticastTag.ino	Tag firmware — joins 4 sessions (one per anchor), broadcasts raw distances via BLE

Addressing Scheme

• Anchor MAC: {0xA0, ANCHOR_ID} where ANCHOR_ID is 0-3
• Tag MAC: {0x00, TAG_ID} where TAG_ID is 1-12
• Session ID: ANCHOR_ID * 100 + GROUP_INDEX + 1

Tags are split into two groups:

• Group 0: Tags 1-6
• Group 1: Tags 7-12

BLE Distance Advertising

Each tag broadcasts raw UWB distance measurements over BLE advertising (no pairing required). Position computation is deferred to the receiver so the tag firmware stays independent of anchor geometry.

• Local name: UWB-T<id> (e.g., UWB-T1)
• Manufacturer data (11 bytes):

Byte	Content
0-1	Company ID 0xFFFF (BLE SIG test/dev, little-endian)
2	TAG_ID
3-4	Distance to A0 in cm (uint16, little-endian, 0xFFFF = invalid)
5-6	Distance to A1 in cm (uint16, little-endian, 0xFFFF = invalid)
7-8	Distance to A2 in cm (uint16, little-endian, 0xFFFF = invalid)
9-10	Distance to A3 in cm (uint16, little-endian, 0xFFFF = invalid)

The advertisement is only updated when any distance value changes to minimize BLE churn. Distances that are stale (no update for 2.5 s) are reported as 0xFFFF.

Configuration

Anchor

Set ANCHOR_ID (0-3) in UWB_MulticastAnchor.ino:

#define ANCHOR_ID  0   // 0, 1, 2, or 3

Tag

Set TAG_ID (1-12) in UWB_MulticastTag.ino:

#define TAG_ID  1   // 1 through 12

Flashing

1. Flash each Portenta C33 with UWB_MulticastAnchor.ino, changing ANCHOR_ID for each (0-3)
2. Flash each Stella with UWB_MulticastTag.ino, changing TAG_ID for each (1-12)
3. Power on anchors first, then tags — anchors drive the ranging schedule

Session Budget

• 2 sessions per anchor (limit: 5 on SR150)
• 4 sessions per tag (limit: 5 on DCU040)

License

Apache 2.0 — see LICENSE.