NCP-UART-HW Firmware for Lidl Silvercrest Gateway

Network Co-Processor (NCP) firmware for the EFR32MG1B232F256GM48 chip found in the Lidl Silvercrest Smart Home Gateway.

This firmware enables communication with Zigbee coordinators like Zigbee2MQTT and Home Assistant ZHA via EZSP (EmberZNet Serial Protocol).

Features

• EZSP v13 - EmberZNet 7.5.1 serial protocol
• Zigbee PRO R22 - Full Zigbee 3.0 support
• Green Power - Support for battery-free devices
• Source routing - 100-entry route table for large networks
• Up to 32 children - Sleepy end-devices supported
• Hardware flow control - RTS/CTS for reliable TCP operation

Hardware

Component	Specification
Zigbee SoC	EFR32MG1B232F256GM48
Flash	256KB
RAM	32KB
Radio	2.4GHz IEEE 802.15.4
UART	PA0 (TX), PA1 (RX), PA4 (RTS), PA5 (CTS) @ 115200 baud

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Option 1: Flash Pre-built Firmware (Recommended)

Pre-built firmware is available in the firmware/ directory. From the repository root:

./flash_efr32.sh <GATEWAY_IP>
# Select [2] NCP-UART-HW

The script handles everything (serialgateway restart, flash, reboot).

Need other formats (.s37, .hex, .bin)? Build from source (Option 2), they will be in build/debug/.

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Option 2: Build from Source

For users who want to customize network parameters or use a different EmberZNet version.

Prerequisites

Install Silicon Labs tools (see 1-Build-Environment/12-silabs-toolchain/):

cd 1-Build-Environment/12-silabs-toolchain
./install_silabs.sh

Or use Docker (see 1-Build-Environment/ for setup):

docker run --rm -v $(pwd):/workspace lidl-gateway-builder \
    /workspace/2-Zigbee-Radio-Silabs-EFR32/24-NCP-UART-HW/build_ncp.sh

Build

cd 2-Zigbee-Radio-Silabs-EFR32/24-NCP-UART-HW
./build_ncp.sh

Output

firmware/
└── ncp-uart-hw.gbl   # For UART flashing (via universal-silabs-flasher)

Other formats (.s37, .hex, .bin) are available in build/debug/ after compilation. Use these for J-Link/SWD flashing or debugging.

Clean

./build_ncp.sh clean

Flash

Via network (same as Option 1):

./flash_efr32.sh <GATEWAY_IP>
# Select [2] NCP-UART-HW

Via J-Link/SWD (if you have physical access to the SWD pads):

commander flash firmware/ncp-uart-hw.gbl \
    --device EFR32MG1B232F256GM48

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Usage

Architecture

+-------------------+    UART     +-------------------+   Ethernet   +---------------------+
|  EFR32MG1B (NCP)  |   115200    |  RTL8196E         |    TCP/IP    |  Host (x86/ARM)     |
|                   |    baud     |  (Gateway SoC)    |              |                     |
|  EmberZNet Stack  |<----------->|                   |<------------>|  Zigbee2MQTT        |
|  + EZSP Protocol  |   ttyS1     |  serialgateway    |   port 8888  |       or            |
|                   |             |  (serial->TCP)    |              |  Home Assistant ZHA |
|  HW Flow Control  |             |                   |              |                     |
+-------------------+             +-------------------+              +---------------------+

The RTL8196E runs serialgateway to bridge the EFR32's UART to TCP port 8888. See 34-Userdata for gateway setup.

Zigbee2MQTT Configuration

Edit configuration.yaml:

serial:
  port: tcp://192.168.1.88:8888
  adapter: ember

Home Assistant ZHA Configuration

Add integration with: - Serial port path: socket://192.168.1.88:8888

Note: Baudrate and flow control are handled by serialgateway on the gateway side, not by the client application.

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Customization

UART baud rate: Only 115200 (default) and 230400 are reliable on this gateway. 460800+ causes UART overruns due to the 16-byte FIFO and userspace latency. See 25-RCP-UART-HW for details.

The build process applies patches to optimize the firmware for the Lidl Gateway. See patches/README.md for details.

Network Parameters

Edit patches/apply_config.sh to modify. For a complete guide, see the Zigbee Network Sizing Guide.

Parameter	Default	Range	RAM/Entry
EMBER_MAX_END_DEVICE_CHILDREN	32	0-64	~40 bytes
EMBER_PACKET_BUFFER_COUNT	255	20-255	~36 bytes
EMBER_SOURCE_ROUTE_TABLE_SIZE	100	2-255	~12 bytes
EMBER_BINDING_TABLE_SIZE	32	1-127	~20 bytes
EMBER_ADDRESS_TABLE_SIZE	12	1-256	~16 bytes
EMBER_NEIGHBOR_TABLE_SIZE	26	16/26	~32 bytes
EMBER_KEY_TABLE_SIZE	12	1-127	~32 bytes

Network Size Presets

Preset	Devices	Children	Buffers	Routes	Bindings
Small	<20	10	75	20	10
Medium	20-50	20	150	50	20
Large (default)	50-100	32	255	100	32
Very Large	100-150	48	255	150	48

Warning: The EFR32MG1B has only 32KB RAM. Current configuration uses ~27KB. Increasing parameters beyond presets may cause instability.

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Technical Details

Memory Usage

Resource	Used	Available
Flash	~200 KB (78%)	256 KB
RAM	~24 KB (75%)	32 KB
NVM3	36 KB	Network data storage

Optimizations Applied

To fit in 256KB flash, the following were removed:

Component	Savings	Reason
Debug print	~12 KB	No debug output needed
ZLL / touchlink	~4 KB	Not used
Virtual UART	~1 KB	Not needed
PTI (Packet Trace)	~2 KB	No debug probe

Features

• RTL8196E Boot Delay: 1-second delay for host UART initialization
• Hardware Flow Control: RTS/CTS required for reliable TCP operation
• NVM3 Storage: 36KB for network credentials and tokens

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Troubleshooting

No response from NCP

1. Verify TCP connection: nc -zv <gateway-ip> 8888
2. Check baud rate matches (115200) on firmware and serialgateway
3. Verify hardware flow control is enabled on serialgateway

EZSP communication errors

1. Ensure Z2M/ZHA is configured for ember adapter
2. Check for EZSP version mismatch (this firmware is EZSP v13)
3. Restart serialgateway with hardware flow control: serialgateway (not -f)

Device won't pair

1. Enable permit join in Z2M/ZHA
2. Factory reset the device
3. Move device closer to coordinator for initial pairing

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Files

24-NCP-UART-HW/
├── build_ncp.sh                 # Build script
├── README.md                    # This file
├── firmware/                    # Pre-built firmware files
│   ├── ncp-uart-hw-7.5.1.gbl
└── patches/
    ├── README.md                # Patch documentation
    ├── apply_config.sh          # Configuration script
    ├── ncp-uart-hw.slcp         # Project config
    ├── main.c                   # Entry point (1s delay)
    └── sl_*.h                   # Configuration headers

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Related Projects

• 25-RCP-UART-HW/ - RCP firmware (CPC protocol, for cpcd + zigbeed)
• 26-OT-RCP/ - OpenThread RCP (for zigbee-on-host)
• 27-Router/ - Autonomous Zigbee router (no host needed)

References

• EZSP Protocol Reference (UG100)
• EmberZNet NCP Guide (UG115)
• AN1233: Zigbee Stack Configuration

License

Educational and personal use. Silicon Labs SDK components under their respective licenses.