Sparkfun ESP32 Thing¶

The Esp32 Thing device is one of the development board created by Sparkfun to evaluate the ESP-WROOM-32 module. It is based on the ESP32 microcontroller that boasts Wifi, Bluetooth, Ethernet and Low Power support all in a single chip.

Pin Mapping¶

Official reference for Sparkfun ESP32 Thing can be found here.

Flash Layout¶

The internal flash of the ESP32 module is organized in a single flash area with pages of 4096 bytes each. The flash starts at address 0x00000, but many areas are reserved for Esp32 IDF SDK and Zerynth VM. There exist two different layouts based on the presence of BLE support.

In particular, for non-BLE VMs:

Start address	Size	Content
0x00009000	16Kb	Esp32 NVS area
0x0000D000	8Kb	Esp32 OTA data
0x0000F000	4Kb	Esp32 PHY data
0x00010000	1Mb	Zerynth VM
0x00110000	1Mb	Zerynth VM (FOTA)
0x00210000	512Kb	Zerynth Bytecode
0x00290000	512Kb	Zerynth Bytecode (FOTA)
0x00310000	512Kb	Free for user storage
0x00390000	448Kb	Reserved

For BLE VMs:

Start address	Size	Content
0x00009000	16Kb	Esp32 NVS area
0x0000D000	8Kb	Esp32 OTA data
0x0000F000	4Kb	Esp32 PHY data
0x00010000	1216Kb	Zerynth VM
0x00140000	1216Kb	Zerynth VM (FOTA)
0x00270000	320Kb	Zerynth Bytecode
0x002C0000	320Kb	Zerynth Bytecode (FOTA)
0x00310000	512Kb	Free for user storage
0x00390000	448Kb	Reserved

Device Summary¶

Microcontroller: Tensilica 32-bit Single-/Dual-core CPU Xtensa LX6
Operating Voltage: 3.3V
Input Voltage: 3.7-6V
Digital I/O Pins (DIO): 28
Analog Input Pins (ADC): 4
UARTs: 3
SPIs: 1
I2Cs: 1
Flash Memory: 4 MB
SRAM: 520 KB
Clock Speed: 240 Mhz
Wi-Fi: IEEE 802.11 b/g/n/e/i:
- Integrated TR switch, balun, LNA, power amplifier and matching network
- WEP or WPA/WPA2 authentication, or open networks

Power¶

Power to the Sparkfun ESP32 Thing is supplied via the on-board USB Micro B connector or directly throught the connector for a 3.7/4.2 V battery. The power source is selected automatically.

If both USB and the LiPo are plugged into the board, the onboard charge controller will charge the LiPo battery at a rate of up to 500mA.

Warning

The ESP32’s operating voltage range is 2.2 to 3.6V. Under normal operation the ESP32 Thing will power the chip at 3.3V. The I/O pins are not 5V-tolerant!

In addition to USB and battery connectors, the VBAT, and VUSB pins are all broken out to both sides of the board. These pins can be used as an alternative supply input to the Thing.

The maximum, allowable voltage input to VUSB is 6V, and VBAT should not be connected to anything other than a LiPo battery. Alternatively, if you have a regulated voltage source between 2.2V and 3.6V, the “3V3” lines can be used to directly supply the ESP32 and its peripherals.

Connect, Register, Virtualize and Program¶

The Sparkfun ESP32 Thing comes with a serial-to-usb chip on board that allows programming and opening the UART of the ESP32 module. The FTDI FT231x is also connected to the boot pins of the module, allowing for a seamless virtualization of the device.

Note

Drivers for the FT231x Module can be downloaded here and are needed for Windows and Mac platforms. In Linux systems, the Sparkfun ESP32 Thing should work out of the box.

Note

For Linux Platform: to allow the access to serial ports the user needs read/write access to the serial device file. Adding the user to the group, that owns this file, gives the required read/write access: Ubuntu distribution –> dialout group; Arch Linux distribution –> uucp group.

Once connected on a USB port, if drivers have been correctly installed, the Sparkfun ESP32 Thing device is recognized by Zerynth Studio. The next steps are:

Select the Sparkfun ESP32 Thing on the Device Management Toolbar (disambiguate if necessary);
Register the device by clicking the “Z” button from the Zerynth Studio;
Create a Virtual Machine for the device by clicking the “Z” button for the second time;
Virtualize the device by clicking the “Z” button for the third time.

Note

No user intervention on the device is required for registration and virtualization process.

After virtualization, the Sparkfun ESP32 Thing is ready to be programmed and the Zerynth scripts uploaded. Just Select the virtualized device from the “Device Management Toolbar” and click the dedicated “upload” button of Zerynth Studio.

Note

No user intervention on the device is required for the uplink process.

Firmware Over the Air update (FOTA)¶

The Firmware Over the Air feature allows to update the device firmware at runtime. Zerynth FOTA in the Sparkfun ESP32 Thing device is available for bytecode and VM.

Flash Layout is shown in table below:

Start address	Size	Content
0x00010000	1Mb	Zerynth VM (slot 0)
0x00110000	1Mb	Zerynth VM (slot 1)
0x00210000	512Kb	Zerynth Bytecode (slot 0)
0x00290000	512Kb	Zerynth Bytecode (slot 1)

For BLE VMs:

Start address	Size	Content
0x00010000	1216Kb	Zerynth VM (slot 0)
0x00140000	1216Kb	Zerynth VM (slot 1)
0x00270000	320Kb	Zerynth Bytecode (slot 0)
0x002C0000	320Kb	Zerynth Bytecode (slot 1)

For Esp32 based devices, the FOTA process is implemented mostly by using the provided system calls in the IDF framework. The selection of the next VM to be run is therefore a duty of the Espressif bootloader; the bootloader however, does not provide a failsafe mechanism to revert to the previous VM in case the currently selected one fails to start. At the moment this lack of a safety feature can not be circumvented, unless by changing the bootloader. As soon as Espressif relases a new IDF with such feature, we will release updated VMs.

Secure Firmware¶

Secure Firmware feature allows to detect and recover from malfunctions and, when supported, to protect the running firmware (e.g. disabling the external access to flash or assigning protected RAM memory to critical parts of the system).

This feature is strongly platform dependent; more information at Secure Firmware - ESP32 section.

Missing features¶

Not all IDF features have been included in the Esp32 based VMs. In particular the following are missing but will be added in the near future:

Touch detection support