Walter
Overview
Walter is a compact IoT development board that combines an Espressif ESP32-S3 SoC with a Sequans Monarch 2 GM02SP LTE-M/NB-IoT/GNSS modem. More information about Walter can be found on the QuickSpot Website [1] and on the QuickSpot GitHub page [2].
Hardware
ESP32-S3-WROOM-1-N16R2 microcontroller:
Xtensa dual-core 32-bit LX7 CPU
16 MiB quad SPI flash memory
2 MiB quad SPI PSRAM
150 Mbps 802.11 b/g/n Wi-Fi 4 with on-board PCB antenna
2 Mbps Bluetooth 5 Low Energy with on-board PCB antenna
Sequans Monarch 2 GM02SP modem:
Dual-mode LTE-M / NB-IoT (NB1, NB2)
3GPP LTE release 14 (Upgradable up to release 17)
Ultra-low, deep-sleep mode in eDRX and PSM
Adaptive +23 dBm, +20 dBm and +14 dBm output power
Integrated LNA and SAW filter for GNSS reception
Assisted and non-assisted GNSS with GPS and Galileo constellations
Integrated SIM card
Nano-SIM card slot
u.FL RF connectors for GNSS and 5G antennas
Inputs & outputs:
24 GPIO pins for application use
UART, SPI, I²C, CAN, I²S, and SD available on any of the GPIO pins
ADC, DAC, and PWM integrated in ESP32-S3
3.3 V software-controllable output
USB Type-C connector for flashing and debugging
22 test points for production programming and testing
On-board reset button
Power supply
5.0 V via USB Type-C
3.0 - 5.5 V via Vin pin
Not allowed to use both power inputs simultaneously
Designed for extremely low quiescent current
Form factor
Easy to integrate via 2.54 mm headers
55 mm x 24.8 mm board dimensions
Pin and footprint compatible with EOL Pycom GPy
Breadboard friendly
Supported Features
Current Zephyr’s Walter board supports the following features:
Interface |
Controller |
Driver/Component |
|---|---|---|
UART |
on-chip |
serial port |
GPIO |
on-chip |
gpio |
PINMUX |
on-chip |
pinmux |
USB-JTAG |
on-chip |
hardware interface |
SPI Master |
on-chip |
spi |
TWAI/CAN |
on-chip |
can |
ADC |
on-chip |
adc |
Timers |
on-chip |
counter |
Watchdog |
on-chip |
watchdog |
TRNG |
on-chip |
entropy |
LEDC |
on-chip |
pwm |
MCPWM |
on-chip |
pwm |
PCNT |
on-chip |
qdec |
GDMA |
on-chip |
dma |
USB-CDC |
on-chip |
serial |
Wi-Fi |
on-chip |
|
Bluetooth |
on-chip |
|
Cellular |
on-board |
modem_cellular |
Prerequisites
Espressif HAL requires WiFi and Bluetooth binary blobs in order work. Run the command below to retrieve those files.
west blobs fetch hal_espressif
Note
It is recommended running the command above after west update.
Building & Flashing
Simple boot
The board could be loaded using the single binary image, without 2nd stage bootloader. It is the default option when building the application without additional configuration.
Note
Simple boot does not provide any security features nor OTA updates.
MCUboot bootloader
User may choose to use MCUboot bootloader instead. In that case the bootloader must be build (and flash) at least once.
There are two options to be used when building an application:
Sysbuild
Manual build
Note
User can select the MCUboot bootloader by adding the following line to the board default configuration file.
CONFIG_BOOTLOADER_MCUBOOT=y
Sysbuild
The sysbuild makes possible to build and flash all necessary images needed to bootstrap the board with the ESP32-S3 SoC.
To build the sample application using sysbuild use the command:
west build -b walter/esp32s3/procpu --sysbuild samples/hello_world
By default, the ESP32 sysbuild creates bootloader (MCUboot) and application images. But it can be configured to create other kind of images.
Build directory structure created by sysbuild is different from traditional Zephyr build. Output is structured by the domain subdirectories:
build/
├── hello_world
│ └── zephyr
│ ├── zephyr.elf
│ └── zephyr.bin
├── mcuboot
│ └── zephyr
│ ├── zephyr.elf
│ └── zephyr.bin
└── domains.yaml
Note
With --sysbuild option the bootloader will be re-build and re-flash
every time the pristine build is used.
For more information about the system build please read the Sysbuild (System build) documentation.
Manual build
During the development cycle, it is intended to build & flash as quickly possible. For that reason, images can be build one at a time using traditional build.
The instructions following are relevant for both manual build and sysbuild. The only difference is the structure of the build directory.
Note
Remember that bootloader (MCUboot) needs to be flash at least once.
Build and flash applications as usual (see Building an Application and Run an Application for more details).
# From the root of the zephyr repository
west build -b walter/esp32s3/procpu samples/hello_world
The usual flash target will work with the walter board
configuration. Here is an example for the Hello World
application.
# From the root of the zephyr repository
west build -b walter/esp32s3/procpu samples/hello_world
west flash
Open the serial monitor using the following command:
west espressif monitor
After the board has automatically reset and booted, you should see the following message in the monitor:
***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
Hello World! walter/esp32s3/procpu
Debugging
ESP32-S3 support on OpenOCD is available at OpenOCD ESP32 [4].
ESP32-S3 has a built-in JTAG circuitry and can be debugged without any additional chip. Only an USB cable connected to the D+/D- pins is necessary.
Further documentation can be obtained from the SoC vendor in JTAG debugging for ESP32-S3 [3].
Here is an example for building the Hello World application.
# From the root of the zephyr repository
west build -b walter/esp32s3/procpu samples/hello_world
west flash
You can debug an application in the usual way. Here is an example for the Hello World application.
# From the root of the zephyr repository
west build -b walter/esp32s3/procpu samples/hello_world
west debug