This page is generated from my GitHub project README. Check out the source code here: NRF54L15_BLE_DEV

!! Work in progress: The current design is untested. This page will be updated after assembly and testing

Overview

This repository contains design files, libraries, and documentation for the NRF BLE transceiver project. It is not an official NRF development board; it is a project I designed as an exercise while learning Altium Designer.

(Renderd with Blender using pcb2blender plugin for KiCAD)

Things to play around with

• 6-axis IMU (BMI270)
• WS2812 Addressable RGB LED
• Coin cell operation
• Antenna switch for External antenna

Folder Structure

3D/				  # Contains STEP and Blender files
Altium/           # Altium project files and libraries
Datasheet/        # Datasheets and reference documents
Gerbers/          # Gerbers with PCB constraints optimized for JLCPCB
Pictures/         # Contains Render and Readme pictures
Reference/        # Additional reference layouts and guides

Getting Started

1. Clone the repository:

   git clone https://github.com/Nandish-KK/NRF54L15_BLE_DEV

2. Open the Altium project file in Altium/Nordic_BLE/Nordic_BLE.PrjPcb.
3. Optionally you can import the Altium project in latest Kicad releases.
4. Review the schematic and PCB files.

Stackup

JLC04101H-7628

This is a 4-layer stackup with both of the Inner layers being solid ground planes.

Project Preview

Schematic

Top 3D View

Top Layer

Bottom Layer

Bottom 3D View

Development bugs and fixes

The nrf54 controller comes with AP_PROTECT enabled by default. The debuggeres are unable to access the cpu and user flash memory for flashing. In order to unlock the AP_PROTECT and get access to the device, the nrf documentation recommends “mass erase”. This process will clear the protection registers and allow for flashing.

If your using pyocd inside the nrf-connect terminal with west. During flash it will automatically detect the protection state and will try to erase before flashing. If that doesn’t work, try external resets.

#from the project directory
$ west flash -d build_1/ -r pyocd

# --- OUTPUT ---
-- west flash: rebuilding
[0/5] Performing build step for 'hello_world'
ninja: no work to do.
[4/5] cd /home/user/path/to/project/dir/hello_world/build_1/_sysbuild && /home/user/ncs/toolchains/b2ecd2435d/usr/local/bin/cmake -E true
-- west flash: using runner pyocd
-- runners.pyocd: Flashing file: /media/renri/Hard_disk_Part1/NRF_playground/hello_world/build_1/merged.hex
0000496 W NRF54L15 APPROTECT enabled: will try to unlock via mass erase [target_nRF54L]
0001425 I Loading /home/user/path/to/project/dir/hello_world/build_1/merged.hex [load_cmd]
[==================================================] 100%
0005148 I Erased 36864 bytes (9 sectors), programmed 36864 bytes (9 pages), skipped 0 bytes (0 pages) at 9.75 kB/s [loader]

If the protection is enabled, the openenocd ‘targets’ command will report the main cpu status as unknown as shown below.

					 --- Locked State ---
> targets
    TargetName         Type       Endian TapName            State       
--  ------------------ ---------- ------ ------------------ ------------
 0* nrf54l.cpu         cortex_m   little nrf54l.cpu         unknown
 1  nrf54l.aux         mem_ap     little nrf54l.cpu         running


					--- Unlocked State ---
 > targets
    TargetName         Type       Endian TapName            State       
--  ------------------ ---------- ------ ------------------ ------------
 0* nrf54l.cpu         cortex_m   little nrf54l.cpu         running
 1  nrf54l.aux         mem_ap     little nrf54l.cpu         running

You can use the following pyocd commands to erase the chip. Although you can connect via openocd, there doesn’t seem to be a relibale way to erase the chip with AP_PROTECT enabled. Use the pyocd provided along with the nrf connect or install the latest version of pyocd if you prefere to use it externally.

$ pyocd erase --mass --target nrf54l

# --- OUTPUT ---
0000395 W NRF54L15 is not in a secure state [target_nRF54L]
0000608 I Mass erasing device... [eraser]
0001324 I Mass erase complete [eraser]

If pyocd command fails to erase/flash with cmsis debugger, try power cycling.

Design Notes

• Hold the Boot button for uploading the CMSIS-DAP firmware for CH552 (first time only)
• Use the toggle switch to select the USB or Coin-cell operation
• The Antenna switch is powered with the GPIO _P1.09 and is controlled by GPIO P1.10; configure GPIOs for proper RF operation.
• Every GPIO used onboard has a bridger solder link. If any project requires these GPIOs externally, simply cut the closed solder bridge trace.

On-Board Debugger

The Board design utilizes a CH552P microcontroller with a CMSIS-DAP firmware as a built-in debugger for NRF microcontroller. The CH552P is opted mainly due to its low cost and smaller footprint. If you are designing your own board and would like to have a micro that is available at sites like digikey, mouser etc, then consider the SAMD11 series from microchip. These are fairly optimized for cost and size.

This project uses the Debugger implementation from wagiminator's CH552-DAPLink project.
Check out his project at: 

> github.com/wagiminator/CH552-DAPLink
> oshwlab.com/wagiminator/ch552g-daplink

License

This work is licensed under CC BY-SA 4.0. (https://creativecommons.org/licenses/by-sa/4.0/)

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