DIP Switch Configuration Guide

Mapping for the 10-position DIP switch on the ESP32-S3 UWB board. All settings are applied live while the board is powered (500 ms debounce, then STM32 reconfiguration).

1. Full mapping

SW	GPIO	Function	ON (HIGH)	OFF (LOW)
SW1	IO11	index bit 0 (LSB)	+1	0
SW2	IO10	index bit 1	+2	0
SW3	IO9	index bit 2	+4	0
SW4	IO46	index bit 3	+8	0
SW5	IO3	index bit 4	+16	0
SW6	IO8	index bit 5 (MSB)	+32	0
SW7	IO7	data rate	850 k	6.8 M (default)
SW8	IO6	LAN (Ethernet)	enabled (DHCP + MQTT)	disabled (default)
SW9	IO5	Gateway mode	enabled	normal mode
SW10	IO4	role	Anchor	Tag

Strapping pins

SW4 (IO46) and SW5 (IO3) are ESP32-S3 strapping pins. Their state at reset can affect boot mode and debug log output — if the board fails to boot, check these switch positions first.

Switches short to 3.3 V (no external pull-down). ESP32 internal pull-downs are enabled. ON = HIGH = 1.

2. Mode behaviour

Normal mode (SW9 OFF)

• On boot, listens to STM32-stored Role/Id/Rate for 2.5 s.
• Match → skip provisioning (fast boot).
• Mismatch → send AT+SETCFG / SETCAP / SETRPT / SAVE / RESTART (~10 s).
• On switch change → 500 ms debounce, then reconfigure (STM32 restarts).
• OLED: A0 6.8M, T15 850k, etc.
• If SW8 ON, ENC28J60 init + MQTT connect runs at end of boot.

Gateway mode (SW9 ON)

• No commands sent to STM32 (provisioning fully skipped).
• Pure passthrough: USB CDC ↔ UART2 + AT+RANGE → JSON.
• SW1–SW6, SW7, SW10 are ignored (effective role/ID is whatever STM32 has saved).
• SW8 (LAN) still works in gateway mode — you can publish over MQTT while acting as a gateway.
• OLED: Gateway.
• Useful as a temporary boot-loop bypass since STM32 is never touched.

3. Index calculation (SW1–SW6)

Binary, SW1 = LSB:

idx = SW1 + (SW2 × 2) + (SW3 × 4) + (SW4 × 8) + (SW5 × 16) + (SW6 × 32)

Desired idx	SW6	SW5	SW4	SW3	SW2	SW1
0	OFF	OFF	OFF	OFF	OFF	OFF
1	OFF	OFF	OFF	OFF	OFF	ON
2	OFF	OFF	OFF	OFF	ON	OFF
3	OFF	OFF	OFF	OFF	ON	ON
5	OFF	OFF	OFF	ON	OFF	ON
10	OFF	OFF	ON	OFF	ON	OFF
16	OFF	ON	OFF	OFF	OFF	OFF
32	ON	OFF	OFF	OFF	OFF	OFF
63	ON	ON	ON	ON	ON	ON

Range: 0 – 63 (matches UWB_TAG_COUNT = 64).

4. Data rate (SW7)

DW3000 UWB data rate. Both the AT+SETCFG freq bit and the AT+SETCAP slot time change together.

SW7	Rate	Slot	Trade-off
OFF	6.8 M	10 ms	Short packets, higher throughput, slightly shorter range
ON	850 k	15 ms	Longer packets (stronger sync), longer range, more noise tolerance

4-1. LAN / MQTT (SW8)

Toggle for the ENC28J60 + MQTT publish stack.

SW8	Behaviour
OFF	LAN disabled. Same as the original behaviour (USB serial + OLED + UART passthrough only).
ON	At boot, init ENC28J60 → DHCP → connect to broker.hivemq.com:1883. JSON built from AT+RANGE is published to topic uwb/range/{A\|T}{idx}.

Pinout (ENC28J60-I/ML)

Signal	GPIO
LAN_SPI_MOSI	IO13
LAN_SPI_MISO	IO14
LAN_SPI_SCLK	IO21
LAN_INT	IO47
LAN_SPI_CE	IO48

MQTT topic / payload

• Topic: uwb/range/A0, uwb/range/T5, etc. (role + idx)
• Client ID: uwb-A0-XXXXXX (last 3 bytes of eFuse MAC)
• Payload (example): {"id":3,"range":[1234,1280,1310,...]} — same JSON as the serial log.

OLED display

With SW8 ON, the line below the version banner shows persistent LAN status:

• LAN ... — DHCP in progress
• L 192.168.1.5 — link OK / MQTT not connected
• M 192.168.1.5 — MQTT connected (publishing)

SW8 is read at boot only. Toggling at runtime does not bring LAN back up — reboot.

5. Common configurations

Anchor 0 @ 6.8 M (typical reference anchor)

• SW10 ON, others OFF
• Display: A0 6.8M

Anchor 5 @ 6.8 M

• SW10 ON
• SW1 ON, SW3 ON (= bit0 + bit2 = 5)
• Display: A5 6.8M

Tag 0 @ 6.8 M

• All OFF (or SW10 OFF + idx 0)
• Display: T0 6.8M

Tag 10 @ 850 k (long range)

• SW10 OFF
• SW2 ON, SW4 ON (= bit1 + bit3 = 10)
• SW7 ON
• Display: T10 850k

PC gateway (receive JSON over USB)

• SW9 ON (other switches don't matter)
• Display: Gateway

6. Serial diagnostics

Every 2 s after boot, the following line is emitted (in addition to the OLED):

[dip] Tag 6.8M idx=0 | SW1..6(idx)=000000  SW7(freq)=0  SW8(LAN)=0  SW9(GW)=0  SW10(role)=0

In gateway mode, prefixed with GW:

[dip] GW Tag 6.8M idx=0 | ...

Right after a switch change, additionally:

dip->A5 6.8M
[provision] A5 6.8M
AT+SETCFG=5,1,1,1
...

7. Caveats

• Boot loop: switch SW9 ON to enter gateway mode — ESP32 stops touching the STM32, so the loop ends. Use the serial log to read the STM32's current state (Role:Anc, Id:0, Rate:6.8M, etc.).
• Strapping pins SW4 (IO46), SW5 (IO3): their state at reset affects ESP32 boot mode. Keep them OFF during flashing.
• STM32 restart on provisioning: changing SW10/SW7 or any index bit triggers an AT+RESTART on the STM32. Ranging data is interrupted for ~5–10 s.
• 3.3 V decoupling: when running multiple boards together, STM32 flash writes and UWB TX spikes can brown out the ESP32 (POWERON reset). Add ≥ 100 µF on the 3.3 V rail.

8. GPIO summary

GPIO	Use
3, 4, 5, 6, 7, 8, 9, 10, 11, 46	DIP SW1–SW10 (reverse order)
13	LAN_SPI_MOSI (ENC28J60)
14	LAN_SPI_MISO (ENC28J60)
16	STM32 RESET (active-low, held HIGH)
17	UART2 TXD → STM32
18	UART2 RXD ← STM32
21	LAN_SPI_SCLK (ENC28J60)
38	I²C SCL (OLED)
39	I²C SDA (OLED)
43, 44	UART0 TX/RX (USB-UART bridge, serial log)
47	LAN_INT (ENC28J60)
48	LAN_SPI_CE (ENC28J60)