CMU TTGO T-Call V1.3 ESP32 SIM800L 2G GPRS WiFi Bluetooth

The CMU TTGO T-Call V1.3 ESP32 + SIM800L is a compact wireless development board combining an ESP32 microcontroller with a SIM800L cellular communication module. It is designed for IoT, remote monitoring, automation, telemetry and other projects requiring both Wi-Fi/Bluetooth connectivity and cellular communication.

Important: The SIM800L cellular modem supports 2G/GPRS networks only. It does not support 3G, 4G or 5G cellular networks. Cellular functionality therefore depends on the availability of compatible 2G network service and an appropriate Nano SIM card.

The ESP32 platform provides a powerful 32-bit Xtensa LX6 processor operating at up to 240MHz, together with 4MB QSPI Flash, 8MB PSRAM and 520KB SRAM. Built-in Wi-Fi and Bluetooth allow the board to communicate with local networks and compatible wireless devices without requiring additional wireless hardware.

The board also includes a USB-C connector and CP2104 USB-to-TTL interface, making it convenient to connect the development board to a computer for programming and serial communication.

A dedicated Nano SIM card slot provides cellular connectivity through the SIM800L module, while the included GPRS antenna helps provide the RF connection required for cellular communication.

The compact board also provides a JST 2-pin battery connector, allowing it to be used with a suitable 3.7V lithium battery. With its combination of Wi-Fi, Bluetooth, GPRS, cellular communication, GPIO and multiple peripheral interfaces, the TTGO T-Call is well suited to connected embedded projects.

Key Features

• ESP32-Based Development Board: Uses an ESPRESSIF ESP32 32-bit microprocessor.
• SIM800L Cellular Module: Provides 2G/GPRS cellular communication.
• 2G Network Only: The cellular modem does not support 3G, 4G or 5G networks.
• Wi-Fi Connectivity: Supports 2.4GHz 802.11 b/g/n wireless networking.
• Bluetooth: Supports Bluetooth 4.2 BR/EDR and BLE.
• 240MHz Processing: ESP32 processor supports clock speeds up to 240MHz.
• 4MB Flash: Provides onboard QSPI Flash memory.
• 8MB PSRAM: Provides additional memory for compatible applications.
• 520KB SRAM: Provides working memory for ESP32 applications.
• CP2104 USB-to-TTL: Provides USB serial communication for programming and development.
• USB-C: Uses a modern USB Type-C connector.
• Nano SIM Support: Designed for Nano SIM cards.
• GPRS Antenna: Includes an external antenna for the cellular module.
• Battery Support: Compatible with a suitable 3.7V lithium battery through the JST connector.
• 500mA Charging: Supports battery charging at approximately 500mA.
• Multiple Interfaces: Supports UART, SPI, SDIO, I2C, PWM, I2S, IR, GPIO, ADC and DAC functions.
• 40MHz Crystal Oscillator: Provides the onboard clock source.
• Compact Design: Measures approximately 78.83 × 28.92 × 8.06mm.
• Low Sleep Current: Approximately 300 A according to the supplied specifications.
• FreeRTOS: Supports the ESP32 FreeRTOS software environment.
• OTA Firmware Updates: Supports firmware updates over a network.
• MQTT Support: Suitable for IoT messaging applications.
• TCP/UDP/HTTP/FTP: Supports common network communication protocols.
• SSL Support: Suitable for applications requiring encrypted network communication.

Cellular Connectivity

The integrated SIM800L module provides cellular connectivity for compatible 2G/GPRS networks.

This allows the board to be used for applications such as:

• Remote data transmission
• SMS-based projects where supported by the modem/software
• GPRS data communication
• Remote monitoring
• IoT telemetry
• Cellular-controlled automation
• Location-independent sensor reporting

Important Network Compatibility

The SIM800L is a 2G GSM/GPRS modem only.

Before purchasing or deploying the product for cellular applications, verify that the intended SIM card and mobile network provide compatible 2G service in the installation area. A 3G, 4G or 5G-only network will not provide cellular connectivity to the SIM800L.

The board uses a Nano SIM card.

ESP32 Processing

The board is built around the ESP32 platform with a 32-bit Xtensa single-/dual-core LX6 microprocessor capable of operating at up to 240MHz.

Memory resources include:

• 4MB QSPI Flash
• 8MB PSRAM
• 520KB SRAM

This processing and memory combination makes the board suitable for applications involving wireless communication, sensor processing, network connectivity, data handling and embedded control.

Wi-Fi Specifications

The integrated ESP32 provides 2.4GHz Wi-Fi connectivity.

• Wi-Fi Standard: 802.11 b/g/n
• Maximum 802.11n Speed: Up to 150Mbps
• Frequency Range: 2.4-2.5GHz
• Frequency Range: 2400-2483.5MHz
• Transmit Power: Up to 22dBm
• Communication Distance: Up to 300m under suitable conditions
• Wi-Fi Modes: Station, SoftAP, SoftAP + Station and P2P
• Security: WPA, WPA2, WPA2-Enterprise and WPS

Actual wireless range and performance depend on environmental conditions, antenna placement, interference, network configuration and other factors.

Bluetooth Specifications

The ESP32 supports Bluetooth connectivity for compatible devices and applications.

• Bluetooth Standard: Bluetooth 4.2 BR/EDR and BLE
• Receiver Sensitivity: Up to -97dBm according to supplied specifications
• Radio: NZIF receiver
• Bluetooth Classes: Class 1, Class 2 and Class 3
• AFH: Supported
• Audio: CVSD and SBC

Software and Networking

The TTGO T-Call supports a range of software and networking functions suitable for IoT development.

Supported Networking Protocols

• IPv4
• IPv6
• SSL
• TCP
• UDP
• HTTP
• FTP
• MQTT

Software Features

• UART firmware download
• OTA firmware upgrades
• Network-based firmware updates
• Host-based firmware updates
• AT command support
• Cloud server development
• Android/iOS application integration
• User firmware development
• FreeRTOS operating environment

These capabilities allow developers to create connected devices that communicate with local networks, cloud services, mobile applications and compatible external devices.

Hardware Interfaces

The board supports multiple hardware interfaces and peripheral functions, including:

• UART
• SPI
• SDIO
• I2C
• LED PWM
• TV PWM
• I2S
• IR
• GPIO
• Capacitive touch sensing
• ADC
• DAC
• LNA pre-amplifier

This range of interfaces provides flexibility when connecting sensors, displays, actuators, storage devices and other electronic modules.

Power Supply and Battery

The board can be powered through its USB-C interface using a 5V / 1A supply.

It also provides battery support through a 2-pin 1.25mm JST connector.

Power Specifications

• USB Power: 5V / 1A
• USB Connector: USB Type-C
• Battery Type: 3.7V lithium battery
• Charging Current: Approximately 500mA
• Battery Connector: JST 2-pin, 1.25mm
• Working Voltage: 2.7-3.6V
• Typical Working Current: Approximately 70mA
• Sleep Current: Approximately 300 A

A suitable battery and charging arrangement should be used according to the board's electrical requirements.

SIM Card and Antenna

The board includes a Nano SIM card interface for the SIM800L cellular module.

The supplied GPRS antenna is designed to connect to the cellular RF interface and is approximately 17cm long.

For reliable cellular communication, position the antenna appropriately and ensure that the SIM card and mobile network are compatible with the SIM800L's 2G/GPRS capabilities.

Operating Conditions

• Working Voltage: 2.7-3.6V
• Working Temperature: -40 C to +85 C
• Typical Working Current: Approximately 70mA
• Sleep Current: Approximately 300 A

Physical Specifications

• Length: 78.83mm
• Width: 28.92mm
• Height: 8.06mm
• Weight: Approximately 11.77g

Its compact dimensions make the board suitable for embedded projects where available installation space is limited.

Applications

The CMU TTGO T-Call can be used for a wide range of connected electronics and IoT applications, including:

• IoT development
• Remote monitoring
• Cellular telemetry
• Wireless sensor networks
• Environmental monitoring
• Remote sensor data collection
• Smart agriculture projects
• Industrial monitoring
• Automation systems
• Remote equipment monitoring
• GPRS data transmission
• Cellular-connected controllers
• Home automation
• Security and alarm projects
• GPS-related projects when paired with suitable external hardware
• Cloud-connected devices
• MQTT IoT projects
• Wi-Fi-enabled devices
• Bluetooth projects
• Educational electronics
• Maker and DIY projects
• Prototype development

Suitable For

The TTGO T-Call is suitable for developers, engineers, makers, students and IoT enthusiasts who require a compact development platform combining:

• ESP32 processing
• Wi-Fi
• Bluetooth
• 2G/GPRS cellular communication
• USB-C programming
• Battery support
• Multiple hardware interfaces

Specifications Summary

• Board: TTGO T-Call V1.3
• Main Processor: ESPRESSIF ESP32
• Processor: Xtensa single-/dual-core 32-bit LX6
• Maximum Clock: 240MHz
• Flash: 4MB QSPI
• PSRAM: 8MB
• SRAM: 520KB
• Cellular Module: SIM800L
• Cellular Network: 2G/GPRS only
• SIM Type: Nano SIM
• Wi-Fi: 802.11 b/g/n, 2.4GHz
• Bluetooth: Bluetooth 4.2 BR/EDR + BLE
• USB-to-TTL: CP2104
• USB Connector: USB-C
• Operating Voltage: 2.7-3.6V
• USB Supply: 5V / 1A
• Battery: 3.7V lithium
• Charging Current: 500mA
• Operating Temperature: -40 C to +85 C
• Dimensions: 78.83 × 28.92 × 8.06mm
• Weight: Approximately 11.77g

What's in the box
1 x CMU TTGO T-Call V1.3 ESP32 + SIM800L Development Board
1 x GPRS Antenna, approximately 17cm
1 x Power Cord
1 x Power Cable
2 x Pin Headers