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fwt_software/docs/lattepanda-iota.md

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LattePanda IOTA — Hardware Notes

Collected 2026-09-11 from vendor documentation and independent reviews (sources at the bottom). Companion to COMPONENTS.md §1 (LattePanda 3 Delta, the board currently deployed on the tower).

Status: desk research. Nothing here has been measured on a physical IOTA. Items marked [VERIFY] must be confirmed against the board or its schematic before anyone cuts a harness.

1. Why this board is different

The IOTA is not a drop-in successor to the 3 Delta. Two changes break existing assumptions:

  1. The co-processor changed from ATmega32U4 (8-bit AVR, 5 V) to RP2040 (32-bit Cortex-M0+, 3.3 V). The gimbal firmware is an AVR/Leonardo PlatformIO project; it must be ported, and the RP2040 I/O pins are not 5 V tolerant.
  2. The expansion layout changed. No M.2 B-key (the 5G modem's slot), no M.2 M-key (NVMe moves to a 16-pin FPC PCIe adapter board), and the header exposes only one PCH-side UART — no PCH I2C.

2. Core specifications

Item LattePanda IOTA LattePanda 3 Delta (current tower board)
CPU Intel Processor N150 "Twin Lake", 4C/4T, up to 3.60 GHz, 6 MB cache Intel Celeron N5105 "Jasper Lake", 4C/4T, 2.0–2.9 GHz
GPU Intel Graphics, 24 EU, up to 1.0 GHz Intel UHD, 450–800 MHz
TDP Configurable 6 W – 15 W ~12 W typical
RAM 8 GB / 16 GB LPDDR5 4800 MT/s, in-band ECC 8 GB LPDDR4 2933 MT/s
Storage 64 GB / 128 GB eMMC 5.1 + microSD 64 GB eMMC 5.1 + microSD
TPM TPM 2.0 (in CPU) —
RTC Yes, 2-pin 1.25 mm, CR2032 included (V1 lacked one; Delta has one)
Dimensions 88 × 70 × 19 mm (vendor page; CNX lists 88 × 77 × 19) 125 × 78 mm
Power in USB-C PD 15 V (power input only), or PH2.0 4-pin 10–15 V DC 12 V DC (7.4–15 V)
OS support Windows 10/11, Ubuntu 22.04 / 24.04 Windows 10/11, Ubuntu, Android
Price ~$129 board only; kits from ~$166 —

Relevance to the fire-watch tower: the N150 is a straight upgrade over the N5105 — newer Gracemont cores, ~1.24× the clock ceiling, LPDDR5 vs LPDDR4. The 10–15 V DC input covers the tower's 12 V rail.

3. Co-processor: RP2040

Item RP2040 (IOTA) ATmega32U4 (Delta)
Core Dual-core Arm Cortex-M0+ @ 133 MHz Single-core 8-bit AVR @ 16 MHz
SRAM 264 KB 2.5 KB
Flash 8 MB 32 KB
I/O logic level 3.3 V — NOT 5 V tolerant 5 V
Host link USB 2.0 CDC (appears as a serial device) USB 2.0 CDC (native USB)
Toolchains Arduino C++, MicroPython, Firmata Arduino C++
Flashing UF2 bootloader: hold BOOTSEL, tap RST, release → mounts as mass storage RPI-RP2, drag the .uf2 avrdude over the CDC port (Leonardo 1200-baud touch)

Internal RP2040 connections (not on the header): GPIO20 = SW button, GPIO21 = RST, GPIO25 = blue LED.

Host-side enumeration

The Delta's Leonardo enumerates as USB 2341:8036 → /dev/serial/by-id/usb-Arduino_LLC_Arduino_Leonardo-if00. An RP2040 running the Arduino-Pico core enumerates as 2e8a:000a (CDC) and 2e8a:0003 in BOOTSEL mode. [VERIFY] the exact VID:PID and by-id string on the real board — the [Serial] device config value and any udev rule key off it.

4. The 36-pin GPIO header (2×18, 2.54 mm)

Pin Signal Dir Level Notes
1 SPK+ Out — Speaker, up to 2 W RMS / 4 Ω
2 SPK− Out —
3 TXD Out 3.3 V PCH serial, COM1 / ttyS0
4 RXD In 3.3 V PCH serial, COM1 / ttyS0
5 GND — —
6 5V Pwr 5 V Power Output 1, 0.5 A max
7–13 GP0 … GP6 I/O 3.3 V RP2040 GPIO
14–16 GP26 … GP28 I/O 3.3 V ADC-capable, 100 nF to GND — unusable for I2C/SPI
17 3.3V Pwr 3.3 V RP2040 rail, 1.2 A max
18 RST In (pull-up) 3.3 V System reset, pull low
19 5V Pwr 5 V Power Output 2, 1.2 A max
20 D− I/O — USB 2.0, native PCH
21 D+ I/O — USB 2.0, native PCH
22 GND — —
23 S0 Out 3.3 V OS-running indicator (200 Ω series, drives an LED)
24 S3 Out 3.3 V OS-sleeping indicator (200 Ω series)
25–31 GP7 … GP13 I/O 3.3 V RP2040 GPIO
32 RUN In 3.3 V RP2040 reset, active low
33 SCLK I/O 3.3 V RP2040 SWCLK (SWD debug)
34 SDIO I/O 3.3 V RP2040 SWDIO (SWD debug)
35 GND — —
36 SW In (pull-up) 3.3 V System power button, pull low

Warnings from the vendor docs

  • Do not draw from 5 V Power Output 1 and Output 2 simultaneously.
  • GP26–GP28 carry 100 nF to ground for ADC stability; avoid them for I2C or any fast edge.
  • Do not apply >3.3 V to any RP2040 pin.

Usable RP2040 GPIO budget

GP0–GP13 (14 clean pins) plus GP26–GP28 (analog-only in practice). GP14–GP25 are not broken out.

RP2040 peripheral options within GP0–GP13:

Peripheral Available pins in GP0–GP13
SPI0 SCK GP2/GP6, TX(MOSI) GP3/GP7, RX(MISO) GP0/GP4, CSn GP1/GP5
SPI1 SCK GP10, TX(MOSI) GP11, RX(MISO) GP8/GP12, CSn GP9/GP13
I2C0 SDA GP0/GP4/GP8/GP12, SCL GP1/GP5/GP9/GP13
I2C1 SDA GP2/GP6/GP10, SCL GP3/GP7/GP11
UART0 TX GP0/GP12, RX GP1/GP13
UART1 TX GP4/GP8, RX GP5/GP9

Any RP2040 pin can also be PWM or PIO. [VERIFY] against the published pinout — the peripheral map above is from the RP2040 datasheet, not from LattePanda.

5. I/O and expansion

Interface IOTA Delta (for comparison)
USB Type-A 3 × USB 3.2 Gen 2 (10 Gbps) 1 × 3.2 Gen2 + 2 × 3.2 Gen1
USB header USB 2.0 pin header (pins 20/21) —
USB-C Power input only (PD 15 V) — no data, no DP-alt USB 2.0 Type-C + DP 1.4 alt
Ethernet 1 × GbE RJ45, WoL (Realtek, r8169) Intel I225-V GbE
Video HDMI 2.1 (4K@60), eDP 1.4b 2-lane (1080p60) HDMI 2.0b, DP via USB-C, eDP 30-pin
M.2 E-key 2230 PCIe 3.0 ×1 / USB 2.0 / CNVio2 — Wi-Fi/BT present
M.2 B-key ABSENT present (2242/2252/2280, SATA/USB2/USB3/SIM)
M.2 M-key ABSENT — use the FPC PCIe adapter present (2280, PCIe 3.0 ×2)
PCIe FPC 16-pin, 0.5 mm, PCIe 3.0 ×1, 2.2 A shared across two 5 V pins —
microSD TF slot Micro-SD + Micro-SIM combo
Audio 3.5 mm jack, speaker via header, HDMI digital 3.5 mm combo
Fan 4-pin 1.25 mm, PWM, 5 V —
UPS 10-pin 1.25 mm USB 2.0 connector —

Known expansion boards

  • DFR1250 — M.2 M-key expansion: converts the 16-pin FPC to an M.2 M-key slot, PCIe 3.0 ×1 (8 GT/s), 2230 and 2280, bus-powered, no drivers. NVMe only — SATA M.2 SSDs are not supported. Measured ~810 MB/s in an independent review.
  • PoE expansion board — works as a standalone gigabit interface.
  • UPS board — reported working only on Windows 10/11; Linux NUT did not see a USB device.

6. Linux behaviour (independent report, Nov 2025)

  • Fedora Server 43 / kernel 6.17.7 installed cleanly, "no quirks or oddities". Ubuntu 22.04/24.04 are the vendor-supported targets.
  • Ethernet is Realtek via r8169.
  • eMMC: ~316 MB/s sequential read, ~175 MB/s write, ~0.15 ms read latency.
  • NVMe over the FPC adapter: ~810 MB/s.
  • Power: ~4.0 W idle; 24.4 W under disk stress; 36.3 W peak under combined CPU+disk, dropping as the CPU throttles.
  • Thermals with the active cooler: ~80 °C initially under sustained all-core load, settling ~70 °C at 2.2–2.3 GHz; ~2.9 GHz on brief single-core bursts. The stock active cooler is loud ("very strong high-pitched whine") — relevant only if anyone has to sit next to it.
  • 24 h stress with the thermal-pad film accidentally left on produced no throttling.
  • 3 USB storage devices ran ~24 h / 72 TB of reads with no kernel instability.
  • RTC present, so the systemd timer problems seen on the V1 are gone.

7. Migration notes (vendor "V1 → IOTA" guide)

  • Voltage: 5 V peripherals now need level shifting. Explicit warning against >3.3 V on any pin.
  • Sketches: existing Arduino code "needs porting" — library support differs, port-manipulation code differs, timing and interrupt handling diverge from 8-bit AVR.
  • Display: MIPI-DSI → eDP 1.4b; the 7-inch MIPI display (FIT0477) is incompatible (replacement FIT1030).
  • Power: micro-USB 5 V → USB-C PD 15 V; internal connector now 10–15 V DC.
  • The guide does not cover bootloader details, Arduino IDE board selection, upload-method changes, or a library compatibility matrix.

8. Open questions — confirm on real hardware

# Question Why it matters
1 Is there any PCH-side I2C/SMBus reachable on the IOTA? The published header shows only COM1. The SHT41 ambient sensor lives on the Delta's /dev/i2c-2 (Synopsys DesignWare LPSS). With no PCH I2C it must move to the RP2040 or to a USB-I2C bridge.
2 Is header COM1 (pins 3/4) 3.3 V TTL or true RS-232 levels? Docs say 3.3 V. The Xsens MTi is on the Delta's RS-232 header at /dev/ttyS0. A level mismatch needs a transceiver or a USB-serial adapter.
3 Exact RP2040 VID:PID and /dev/serial/by-id/ string. [Serial] device and the udev rule.
4 Does the header COM1 enumerate as ttyS0 under Linux, and is it enabled in BIOS? IMU device path.
5 Can the Quectel RM520N-GL (M.2 B-key) be rehomed? No B-key slot on the IOTA.
6 USB3 LPM and usbfs_memory_mb behaviour on the N150 xHCI. Known issue #19 — the Alvium stalls without these.
7 Sustained JPEG XL encode throughput at the production frame size. Sets the achievable capture rate. Measured 2026-09-30 on tower 121: a full-resolution (5328×3040) colour frame at distance 0.8, effort 4 takes 0.67 s with 3 threads (0.73 s while the camera streams), 0.50 s with 4; on a sharp, detailed frame 0.74 s with 4 threads, and one save worker keeps up with about one frame per 0.8 s. The 3 Delta (tower 111) is about 55% slower per pixel (camera-capture-measurements.md).

Sources