NX40 PCB Integration
This page provides a practical checklist for integrating the NX40 module into a custom host PCB.
It focuses on board-level integration. Detailed pad/pin grouping is covered in NX40 Pad / Pin Layout, and assembly handling is covered in NX40 Handling & Soldering.
PCB Integration Flow
| Step | Action |
|---|---|
| 1 | Select the NX40 model |
| 2 | Place the module on the host PCB |
| 3 | Connect power and ground |
| 4 | Add required decoupling capacitors |
| 5 | Route SWD programming/debug pins |
| 6 | Route reset and required GPIO |
| 7 | Check external Flash option and firmware configuration |
| 8 | Check chip antenna area or external RF path |
| 9 | Add test points for bring-up |
| 10 | Validate the first prototype |
Module Placement
Place the module so that power, debug, GPIO, and antenna constraints can be satisfied.
| Area | Recommendation |
|---|---|
| Antenna side | Keep clear from metal, battery, shield, and dense copper |
| Debug access | Keep SWD pins accessible |
| Test points | Add test points for power, ground, reset, and debug |
| Mechanical clearance | Avoid locations exposed to cable stress or enclosure pressure |
| RF validation | Test placement with the final enclosure |
Power and Ground
| Signal / Area | Recommendation |
|---|---|
| Power rail | Follow the final NX40 schematic and datasheet |
| GND | Connect all required ground pads to a solid ground reference |
| Decoupling | Place capacitors close to power pins |
| Return path | Keep ground return short and low impedance |
| Power test point | Add a test point for measurement |
| Current limit | Use a current-limited supply during first power-on |
Do not assume NX15 power values for NX40. Confirm the final NX40 power requirement from the NX40 schematic or datasheet.
Programming and Debug Access
Keep SWD access available during development and production.
| Signal | Purpose | Recommendation |
|---|---|---|
| SWDIO | Programming/debug data | Route to header or test pad |
| SWDCLK | Programming/debug clock | Route to header or test pad |
| RESET / NRESET | Reset and recovery | Route to header, button, or test pad |
| GND | Debug reference | Place close to SWD signals |
| Target voltage | Debugger reference | Add if required by the debugger |
Even if the final product does not expose a debug connector, test pads are strongly recommended for flashing, recovery, and production programming.
External Flash Consideration
NX40 models may be built with or without external SPI Flash.
| Model Type | Integration Check |
|---|---|
| 32 models | Confirm Flash part, routing, and firmware configuration |
| 00 models | Confirm firmware does not require external Flash |
| Prototype | Check Flash read/write or storage behavior early |
| Production | Verify correct model and firmware pairing |
A mismatch between hardware Flash option and firmware configuration can cause boot failure, storage errors, or unexpected runtime behavior.
GPIO and Peripheral Routing
NX40 GPIO and peripheral signals should be routed according to the firmware board configuration.
| Interface | Routing Note |
|---|---|
| UART | Confirm TX/RX direction and voltage level |
| SPI | Keep clock and data routing clean |
| I2C | Add pull-up resistors as required |
| PWM | Check output load and drive requirement |
| ADC | Keep analog traces away from noisy signals |
| GPIO | Confirm active level, pull-up/down, and wake-up behavior |
| SWD | Keep accessible and avoid unnecessary stubs |
Antenna Integration Reminder
This page does not repeat full antenna rules, but antenna constraints must be checked before PCB release.
| Variant | Required Check |
|---|---|
| NX40i | Chip antenna keep-out and placement |
| NX40E | External antenna connector, RF trace, and ground reference |
For full details, see the NX40 antenna design page in the NX40 Series BLE Module section.
Bring-up Test Points
Add test points for early validation.
| Test Point | Purpose |
|---|---|
| Power rail | Verify supply voltage |
| GND | Measurement reference |
| SWDIO | Programming/debug |
| SWDCLK | Programming/debug |
| RESET / NRESET | Reset and recovery |
| UART TX/RX | Optional log or host communication |
| Key GPIO | Application-specific validation |
First Prototype Checklist
Before firmware testing:
| Check | Status |
|---|---|
| Correct NX40 model mounted | ☐ |
| Power rail verified | ☐ |
| Ground continuity checked | ☐ |
| No VDD-to-GND short | ☐ |
| Decoupling capacitors installed | ☐ |
| SWDIO / SWDCLK accessible | ☐ |
| Reset path accessible | ☐ |
| Flash option matches firmware | ☐ |
| Antenna layout reviewed | ☐ |
| No visible soldering defect | ☐ |
| Current limit set for first power-on | ☐ |