M0213 VOXL 2 Wifi Addon
Table of contents
Overview
The M0213 VOXL 2 Wifi Addon is a Wi-Fi/Bluetooth expansion board for VOXL 2 and VOXL 2 Mini built around the Bots Unlimited SP-01-100 “Sparrow” LGA module. It mounts to the VOXL 2 legacy expansion (B2B) connector and provides:
- Dual-band 802.11ac Wi-Fi (2.4 GHz / 5 GHz), 2x2 MIMO
- Bluetooth 5.3 (Not supported in current SDK)
- Voltage level shifting between the VOXL 2’s 1.8 V GPIO domain and the board’s 3.3 V legacy peripheral domain
- A 12-pin legacy connector exposing SPI, I2C, UART, and two spare GPIOs at 3.3 V
- Three U.FL antenna connectors (Wi-Fi Path A, Wi-Fi Path B, Bluetooth)
- A fast-boot switch for forcing VOXL 2 into fastboot/USB boot mode
Key Specifications
| Parameter | Value |
|---|---|
| Wi-Fi module | Bots Unlimited SP-01-100 “Sparrow”, 22 x 22 mm LGA. Sparrow Product Page |
| Wi-Fi standard | Dual-band 802.11ac, 2x2 MIMO, up to 866 Mbps |
| Bluetooth | Bluetooth 5.3 |
| RF output power | Up to 30 dBm (2.4 GHz), up to 26.6 dBm (5 GHz) |
| RF kill switch | Hardware RF kill, FAA-compliant |
| Host interfaces (module) | PCIe, USB 2.0/3.0, SDIO (CONFIG_HOST-selectable) |
| Operating temperature (module) | -40 °C to +85 °C |
| Compliance | NDAA-compliant; FCC and Wi-Fi CERTIFIED® pending |
| Board input power | VDC_5V_LOCAL (fused 5 A) and VREG_3P3V_LOCAL |
| Sparrow module max draw, 5 V rail | ~1.7 A |
| Sparrow module max draw, 3.3 V rail | ~1 A |
| Host connector | J1, QTH-030-01-X-D-A, 60-pin legacy B2B |
| Legacy peripheral connector | J3, SM12B-GHS-TB, 12-pin |
| Antenna connectors | J2 (Bluetooth), J4 (Wi-Fi Path A), J5 (Wi-Fi Path B) — all U.FL (U.FL-R-SMT-1(10)) |
| I2C level translator | TI TCA9517DGKR |
| GPIO/UART/SPI level shifters | 5x TI SN74LVC2T45YZPR (dual-bit, auto-direction) |
| ESD protection | 10x PTVS3V3D1BALYL TVS diode array (D1-D10) on level-shifted lines |
Board Architecture
The board is organized into three functional sections (matching the three schematic sheets):
- VOXL Interface — the 60-pin legacy B2B connector (J1) to VOXL 2 / VOXL 2 Mini, 5 V and 1.8 V/3.3 V rail inputs, and the fastboot switch.
- Level Shifting & GPIO — five SN74LVC2T45 auto-direction-sensing translators moving SPI, UART, and spare GPIO signals between the VOXL 2’s 1.8 V domain and the board’s 3.3 V legacy domain, plus a TCA9517 I2C level translator, TVS protection, and the 12-pin legacy peripheral connector (J3).
- Sparrow Module — the SP-01-100 Wi-Fi/BT module (U2A/U2B footprint), its power decoupling, CONFIG_HOST interface-select straps, and the three U.FL antenna connectors.
1. VOXL Interface (J1, Legacy B2B Connector)
J1 is a 60-pin QTH-030-01-X-D-A board-to-board connector. Key nets carried across it:
| Net | Direction (VOXL 2 → board unless noted) | Notes |
|---|---|---|
VDC_5V_LOCAL | Power in | Fused at 5 A on this board; Sparrow module max draw is ~10 W at 5 V |
VREG_S4A_1P8 | Power in | 1.8 V rail, VOXL 2 GPIO domain reference |
VREG_3P3V_LOCAL | Power in | 3.3 V rail, legacy peripheral domain |
GPIO_54_SPI17_SCLK, GPIO_55_SPI17_CS, GPIO_52_SPI17_MISO, GPIO_53_SPI17_MOSI | Bidirectional | SPI17 bus, level-shifted to legacy 3.3 V SPI on J3 |
GPIO_125_I2C9_SDA, GPIO_126_I2C9_SCL | Bidirectional | I2C9 bus, level-translated to legacy 3.3 V I2C on J3 |
GPIO_22_UART7_TXD, GPIO_23_UART7_RXD | Bidirectional | UART7, level-shifted to legacy 3.3 V UART on J3 |
V2_GPIO_32, V2_GPIO_33 | Bidirectional | Spare GPIOs, level-shifted and exposed as GPIO_A / GPIO_B on J3 |
GPIO_131_USB_RESET | VOXL 2 → board | Drives PMIC_DISABLE_N on the Sparrow module directly (1.8 V VIO, no level shift needed) — used to reset/power down the Wi-Fi module |
GPIO_35_DBG_UART12_RX, GPIO_34_DBG_UART12_TX | — | Present on connector, not populated/routed further on this board (marked unused on sheet 1) |
SDM_FORCE_USB_BOOT | — | Present on connector, not populated/routed further on this board |
USB1 SS TX+/TX-, RX+/RX-, HS D+/D-, USB1_SS_TX_N/P, etc. | Bidirectional | Routed to the Sparrow module’s muxed USB3/PCIe SerDes lanes (see CONFIG_HOST section below) |
USB_HS_ID | — | Present on connector, not populated/routed further on this board |
PM_RESIN_N | Bidirectional | Also routed to the fastboot switch, S1 |
Fastboot switch (S1): a momentary switch (EVP-BB2A9B000) pulls PM_RESIN_N low through R13 (100 Ω) to force VOXL 2 into its reset/fastboot sequence.
2. Level Shifting & GPIO
Five SN74LVC2T45YZPR dual-channel, auto-direction-sensing level translators (IC1-IC5) bridge the VOXL 2’s 1.8 V GPIO rail (VREG_S4A_1P8, VCCA side) to the board’s 3.3 V legacy rail (VREG_3P3V_LOCAL, VCCB side):
| Device | 1.8 V side (VCCA) | 3.3 V side (VCCB) |
|---|---|---|
| IC1 | V2_GPIO_32, V2_GPIO_33 | GPIO_A, GPIO_B |
| IC2 | V2_GPIO_32, V2_GPIO_33 | GPIO_A, GPIO_B |
| IC3 | GPIO_23_UART7_RXD, GPIO_52_SPI17_MISO | LEG_UART_RX_3P3V, LEG_SPI_CONN_MISO_3P3V |
| IC4 | GPIO_22_UART7_TXD, GPIO_53_SPI17_MOSI | LEG_UART_TX_3P3V, LEG_SPI_CONN_MOSI_3P3V |
| IC5 | GPIO_54_SPI17_SCLK, GPIO_55_SPI17_CS | LEG_SPI_CONN_SCLK_3P3V, LEG_SPI_CONN_CS_3P3V |
Each level-shifted line is protected by a PTVS3V3D1BALYL TVS diode (D1-D10, one per line) referenced to ground.
I2C level translation: U1 (TCA9517DGKR) translates GPIO_125_I2C9_SDA / GPIO_126_I2C9_SCL (1.8 V side, VCCA) to LEG_I2C_SDA_3P3V / LEG_I2C_SCL_3P3V (3.3 V side, VCCB). Pull-ups: R1/R6 (2.2 kΩ) on the 1.8 V side, R11/R12 (2.2 kΩ) on the 3.3 V side.
The TCA9517 is a fixed-direction (VCCA → VCCB step-up) I2C bus voltage-level translator, not a general bidirectional buffer — if this board is used with multiple downstream I2C devices sharing the translated bus, standard I2C address-sequencing/addressing rules still apply on the 3.3 V side.
Legacy peripheral connector (J3, SM12B-GHS-TB, 12-pin):
| Pin | Signal |
|---|---|
| 1 | LEG_SPI_CONN_MISO_3P3V |
| 2 | LEG_SPI_CONN_MOSI_3P3V |
| 3 | LEG_SPI_CONN_SCLK_3P3V |
| 4 | LEG_SPI_CONN_CS_3P3V |
| 5 | GPIO_A |
| 6 | GPIO_B |
| 7 | LEG_I2C_SDA_3P3V |
| 8 | LEG_I2C_SCL_3P3V |
| 9 | LEG_UART_TX_3P3V |
| 10 | LEG_UART_RX_3P3V |
| 11 | (shield/mechanical, tied GND) |
| 12 | (shield/mechanical, tied GND) |
3. Sparrow Module (U2A/U2B, SP-01-100)
The Sparrow module footprint is split across two schematic symbols, U2A and U2B, both SP-01-100 (Bots Unlimited).
Power:
VREG_3P3V_LOCAL→ module 3.3 V pins, decoupled with C17-C20 (2x 47 µF, 2x 0.1 µF); max draw ~1 AVDC_5V_LOCAL→ module 5 V pins, decoupled with C21-C24 (2x 47 µF, 2x 0.1 µF); max draw ~1.7 A- The module’s internal boost converter option is not used:
V_BOOST_INis left connected to a test point only, and5V_BOOST_DISABLE_Nis tied low to disable it.
Reset/power control: GPIO_131_USB_RESET from the VOXL 2 connects directly to PMIC_DISABLE_N on the module — no level shifting is required since the module’s VIO is 1.8 V, matching the VOXL 2 GPIO. This line is used to reset and power down the Sparrow module.
Host interface mux (CONFIG_HOST[2:0]): The module’s USB3.0 TX/RX SerDes lanes are muxed with PCIe, and the WLAN/Bluetooth host interfaces are jointly selected by three strapping pins, CONFIG_HOST_0/1/2, each with an optional 51 kΩ pull-down (R25/R26/R27, all marked DNP in this design) to an internal pull-up:
| CONFIG_HOST[2:0] | WLAN interface | Bluetooth interface |
|---|---|---|
| 000 | SDIO | UART |
| 001 | SDIO | SDIO |
| 010 | PCIe | USB 2.0 |
| 011 | PCIe | UART |
| 100 | USB 3.0/2.0 | UART |
| 101 | USB 3.0/2.0 | USB 2.0 |
| 110 | USB 3.0/2.0 | USB 3.0/2.0 |
| 111 | USB 3.0 | USB 3.0 |
RF paths and antenna connectors:
| Connector | Path | Series component | Notes |
|---|---|---|---|
| J2 | Bluetooth (RF_BT) | R16 (0 Ω) | U.FL (U.FL-R-SMT-1(10)) |
| J4 | Wi-Fi Path A (RF_A) | R17 (0 Ω) | U.FL |
| J5 | Wi-Fi Path B (RF_B) | R18 (0 Ω) | U.FL |
Each path also has DNP component footprints (e.g., C26/C28/C30, R25-style pads) provided for optional matching/filtering — not populated in this revision.
Mechanical
- Two mounting holes, H1 and H2 (plated, tied to GND).
- Board outline/keep-outs: TODO — not present in the ECAD schematic export; needs the mechanical/fab drawing.
References
- Sparrow LGA Long Range Wi-Fi Module (SP-01-100) product page — Bots Unlimited