Seeed Studio LoRa-E5 mini

Overview

LoRa-E5 mini is a compacted-sized development board suitable for the rapid testing and building of small-sized LoRa device, exposing all capabilities of Seeed Studio LoRa-E5 STM32WLE5JC module.

Hardware

The boards’ LoRa-E5 Module packages a STM32WLE5JC SOC, a 32MHz TCXO, and a 32.768kHz crystal oscillator in a 28-pin SMD package. This STM32WLEJC SOC is powered by ARM Cortex-M4 core and integrates Semtech SX126X LoRa IP to support (G)FSK, BPSK, (G)MSK, and LoRa modulations.

• LoRa-E5 STM32WLE5JC Module with STM32WLE5JC multiprotocol LPWAN single-core 32-bit microcontroller (Arm® Cortex®-M4 at 48 MHz) in 28-pin SMD package featuring:

  • Ultra-low-power MCU

  • RF transceiver (150 MHz to 960 MHz frequency range) supporting LoRa®, (G)FSK, (G)MSK, and BPSK modulations

  • 256-Kbyte Flash memory and 64-Kbyte SRAM

  • Hardware encryption AES256-bit and a True random number generator

• 1 user LED

• 2 serial communication (RX/TX) LEDs

• 1 boot/user and 1 reset push-button

• 32.768 kHz LSE crystal oscillator

• 32 MHz HSE oscillator

• Board connectors:

  • USB Type-C connector

  • +/- (battery) power input pins (3-5V)

  • SMA-K and IPEX antenna connectors

• Delivered with SMA antenna (per default IPEX connector is disconnected)

• Flexible power-supply options: USB Type C or 3-5V battery soldered to +/- pins

• Suitable for rapid prototyping of end nodes based on LoRaWAN, Sigfox, wM-Bus, and many other proprietary protocols

• All GPIOs led out from the LoRa-E5 STM32WLE5JC module

• 4x M2 mounting holes

More information about the board can be found at the LoRa-E5 mini Wiki.

More information about LoRa-E5 STM32WLE5JC Module can be found here:

• LoRa-E5 STM32WLE5JC Module Wiki

• LoRa-E5 STM32WLE5JC Module datasheet

• STM32WLE5JC datasheet

• STM32WLE5JC reference manual

• STM32WLE5JC on www.st.com

Supported Features

The Zephyr LoRa-E5 mini configuration supports the following hardware features:

Interface	Controller	Driver/Component
ADC	on-chip	adc
AES	on-chip	crypto
COUNTER	on-chip	rtc
CLOCK	on-chip	reset and clock control
FLASH	on-chip	flash
GPIO	on-chip	gpio
I2C	on-chip	i2c
MPU	on-chip	arch/arm
NVIC	on-chip	arch/arm
PINMUX	on-chip	pinmux
RADIO	on-chip	LoRa
SPI	on-chip	spi
UART	on-chip	serial port-polling; serial port-interrupt
WATCHDOG	on-chip	independent watchdog

Other hardware features are not yet supported on this Zephyr port.

The default configuration can be found in the defconfig and dts files:

• boards/arm/lora_e5_mini/lora_e5_mini_defconfig

• boards/arm/lora_e5_mini/lora_e5_mini.dts

Connections and IOs

LoRa-E5 mini has 4 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.

Available pins:

Default Zephyr Peripheral Mapping:

• USART_1 TX : PB6

• USART_1 RX : PB7

• I2C_2_SCL : PB15

• I2C_2_SDA : PA15

• BOOT_PB : PB13

• LED_1 : PB5

System Clock

LoRa-E5 mini board System Clock could be driven by the low-power internal (MSI), High-speed internal (HSI) or High-speed external (HSE) oscillator, as well as main PLL clock. By default System clock is driven by the MSI clock at 48MHz.

Programming and Debugging

Applications for the lora_e5_mini board configuration can be built the usual way (see Building an Application).

In the factory the module is flashed with an DFU bootloader, an AT command firmware, and the read protection level 1 is enabled. So before you can program a Zephyr application to the module for the first time you have to reset the read protection to level 0. In case you use an st-link debugger you can use the STM32CubeProgrammer GUI to set the RDP option byte to AA, or use the STM32_Programmer_CLI passing the --readunprotect command to perform this read protection regression. The RDP level 1 to RDP level 0 regression will erase the factory programmed AT firmware, from which seeed has neither released the source code nor a binary. Also, note that on the module the BOOT0 pin of the SOC is not accessible, so the system bootloader will only be executed if configured in the option bytes.

Flashing

The LoRa-E5 mini does not include a on-board debug probe. But the module can be debugged by connecting an external debug probe to the 2.54mm header. Depending on the external probe used, openocd, the stm32cubeprogrammer, pyocd, blackmagic, or jlink runner can be used to flash the board. Additional notes:

• Pyocd: For STM32WL support Pyocd needs additional target information, which can be installed by adding “pack” support with the following pyocd command:

$ pyocd pack --update
$ pyocd pack --install stm32wl

Flashing an application to LoRa-E5 mini

Connect the LoRa-E5 to your host computer using the external debug probe. Then build and flash an application. Here is an example for the Hello World application.

Run a serial host program to connect with your board: Per default the console on usart1 is available on the USB Type C connector via the built-in USB to UART converter.

$ picocom --baud 115200 /dev/ttyACM0

Then build and flash the application.

# From the root of the zephyr repository
west build -b lora_e5_mini samples/hello_world
west flash

Debugging

You can debug an application in the usual way. Here is an example for the Blinky application.

# From the root of the zephyr repository
west build -b lora_e5_mini samples/basic/blinky
west debug