TTGO T-Call (LilyGO)

Development Board

Code name: ESP32_DEV

TTGO T-Call (LilyGO) is a development board based on the ESP32 microcontroller using XTENSA architecture.

This board features a maximum CPU frequency of 240 MHz and 4MB flash memory.

About TTGO T-Call (LilyGO)

The TTGO T-Call is a powerful ESP32 development board designed for cellular IoT applications, featuring integrated GSM/GPRS connectivity alongside Wi-Fi 802.11 b/g/n and Bluetooth 4.2 + BLE. 📶📱

Powered by an ESP32 dual-core processor at 240 MHz, with 4MB/8MB flash memory and 8MB PSRAM, it's optimized for demanding IoT projects requiring reliable remote connectivity. ⚡

The board supports multiple cellular modules: SIM800H (2G GSM/GPRS) and A7670E (LTE/4G) for global cellular communication. It includes a nano SIM card slot, GSM antenna connector, and comprehensive cellular interfaces. 🔌

Features USB Type-C for programming, Li-Po battery support with charging circuit, and extensive GPIO pins supporting ADC, DAC, PWM, I2C, SPI, UART, I2S, and CAN interfaces. Operating at 3.3V with robust power management. 🔋

Where to Buy TTGO T-Call (LilyGO)

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📋 Technical Specifications

Complete technical specification details for TTGO T-Call (LilyGO)

🔌 USB

Type Type-C

Serial Chip CH9102

🛰️ Connectivity

WiFi 802.11 b/g/n (2.4 GHz)

Bluetooth 4.2

BLE 4.2

GSM/GPRS Yes

LTE (A7670E model) Yes

🧠 Microcontroller

Model esp32

Clock Speed 240 MHz

Flash Size 4MB

Architecture xtensa

✨ Features & Pins

Digital IO 30

Analog Input 16

PWM 19

Interrupts 16

• Cellular Connectivity
• Li-Po Battery Support
• Nano SIM Slot

TTGO T-Call (LilyGO) Pinout Diagram

Complete pin reference for TTGO T-Call (LilyGO)

The TTGO T-Call pinout provides extensive connectivity options for cellular IoT projects. Power management includes 5V input, 3.3V regulated output, and battery charging circuitry.

Cellular connectivity features dedicated SIM card slot and GSM ANT antenna connector. Communication interfaces include multiple UART channels for cellular module communication, plus standard ESP32 GPIO pins.

GPIO pins support digital I/O, ADC (18 channels), PWM, and multiple protocols. The board includes EN reset button and comprehensive peripheral interfaces for sensor integration and external device connectivity.

✅ Safe Pins to Use

These pins are safe for general GPIO usage without boot or system conflicts

RXD0

TXD0

IO18

IO19

IO21

IO22

IO23

IO25

IO26

IO27

IO32

IO33

💡 Why Are These Pins Safe?

✓ No boot sequence involvement

✓ No flash/PSRAM connections

✓ No USB or JTAG conflicts

✓ Freely assignable without issues

⚠️ Pins to Avoid or Use with Caution

Reserved for critical functions. Misuse may cause boot failures, programming issues, or system conflicts.

🔄 Strapping Pins

Boot behavior & flash voltage

🐛 JTAG Debugging

Low-level debugging interface

🔌 USB Pins

USB Serial/JTAG communication

💾 Flash/SPI Pins

Memory & PSRAM connections

📡 UART Serial

Debugging & firmware uploads

PIN	Label	Why Avoid	Type
IO0	GPIO0	Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.	🛠️ Strapping
IO2	GPIO2	If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.	🛠️ Strapping
IO4	GPIO4	Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).	🛠️ Strapping
IO5	GPIO5	Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.	🛠️ Strapping
IO12	MTDI (GPIO12)	Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used.	🛠️ Strapping
IO13	MTCK (GPIO13)	Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.	🪛 Other
IO14	MTMS (GPIO14)	Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.	🪛 Other
IO15	MTDO (GPIO15)	Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.	🛠️ Strapping
IO16	GPIO16	Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.	⚡ Flash
IO17	GPIO17	Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.	⚡ Flash
IO34	GPIO34	Cannot be used as output (no drive capability); only suitable for analog/digital input.	🪛 Other
IO35	GPIO35	Cannot be used as output; only suitable for input.	🪛 Other

TTGO T-Call (LilyGO) Additional Information

More details about TTGO T-Call (LilyGO)

TTGO T-Call Cellular Modules

📱 Available Models

SIM800H: 2G GSM/GPRS module supporting quad-band GSM (850/900/1800/1900MHz) and GPRS data transmission
A7670E: LTE Cat.1 module with global LTE bands, ideal for IoT applications requiring higher data speeds
SIM800L: Compact 2G module option for basic cellular connectivity

⚠️ Important Notes

The A7670E module has LTE band limitations in some regions (e.g., US LTE bands may not be fully supported). Check cellular band compatibility for your location. SIM800H provides reliable 2G connectivity but limited data speeds.

💡 Perfect For

Ideal for remote monitoring, asset tracking, smart agriculture, and any IoT project requiring cellular connectivity with WiFi/Bluetooth backup options.

Useful Links

Datasheets and resources for TTGO T-Call (LilyGO)

ESP32 Datasheet

Microcontroller reference

TTGO T-Call Store Page

https://lilygo.cc/products/t-call-v1-4?srsltid=AfmBOoooYx6nHqpxmEssebd9GxFJgXYAjM-eqgFyp0uEII_8KKvC4XXS

TTGO T-Call (LilyGO) Custom Pin Mapping

Pin configuration and GPIO mapping for TTGO T-Call (LilyGO)

Digital I/O Pins

Interrupt Pins

Analog Inputs

PWM Pins

Pin	Function	ESP Pin	I/O Type	Description
4	TX	GPIO17	OUTPUT	UART2 TX for Cellular Module
5	RX	GPIO16	INPUT	UART2 RX for Cellular Module
6	IO0	GPIO0	BIDIRECTIONAL	GPIO0, Boot Mode Selection
7	IO2	GPIO2	BIDIRECTIONAL	GPIO2, General Purpose I/O
8	IO4	GPIO4	BIDIRECTIONAL	GPIO4, General Purpose I/O
9	IO5	GPIO5	BIDIRECTIONAL	GPIO5, General Purpose I/O
10	IO12	GPIO12	BIDIRECTIONAL	GPIO12, ADC or GPIO
11	IO13	GPIO13	BIDIRECTIONAL	GPIO13, ADC or GPIO
12	IO14	GPIO14	BIDIRECTIONAL	GPIO14, ADC or GPIO
13	IO15	GPIO15	BIDIRECTIONAL	GPIO15, ADC or GPIO
14	IO16	GPIO16	BIDIRECTIONAL	GPIO16, General Purpose I/O
15	RXD0	GPIO3	INPUT	UART0 Receive
16	TXD0	GPIO1	OUTPUT	UART0 Transmit
17	IO17	GPIO17	BIDIRECTIONAL	GPIO17, General Purpose I/O
18	IO18	GPIO18	BIDIRECTIONAL	GPIO18, General Purpose I/O
19	IO19	GPIO19	BIDIRECTIONAL	GPIO19, General Purpose I/O
20	IO21	GPIO21	BIDIRECTIONAL	GPIO21, I2C SDA
21	IO22	GPIO22	BIDIRECTIONAL	GPIO22, I2C SCL
22	IO23	GPIO23	BIDIRECTIONAL	GPIO23, SPI MOSI
23	IO25	GPIO25	BIDIRECTIONAL	GPIO25, DAC1
24	IO26	GPIO26	BIDIRECTIONAL	GPIO26, DAC2
25	IO27	GPIO27	BIDIRECTIONAL	GPIO27, ADC
26	IO32	GPIO32	BIDIRECTIONAL	GPIO32, ADC
27	IO33	GPIO33	BIDIRECTIONAL	GPIO33, ADC
28	IO34	GPIO34	INPUT	GPIO34, ADC Input Only
29	IO35	GPIO35	INPUT	GPIO35, ADC Input Only

Legend

Function Pin role

GPIO ESP32 pin

I/O Direction

# Pin number

Pin Mappings

Complete pinout and GPIO mapping for TTGO T-Call (LilyGO)

Digital I/O Pins

Interrupt Pins

Analog Inputs

PWM Pins

Pin	Analog	Touch	PWM	Other
0		T1
1			PWM	TX
2	A12	T2	PWM
3			PWM	RX
4	A10	T0	PWM
5			PWM
12	A15	T5	PWM
13	A14	T4	PWM
14	A16	T6	PWM
15	A13	T3	PWM
16			PWM
17			PWM
18			PWM
19			PWM
21			PWM	SDA
22			PWM	SCL
23			PWM	MOSI
25	A18			DAC1
26	A19			DAC2
27	A17	T8	PWM
32	A4	T9	PWM
33	A5	T10	PWM
34	A6			INPUT
35	A7			INPUT

Legend

A0 Analog input

T0 Touch sensor

PWM PWM capable

RX/TX Serial pins

LED Built-in LED

# Pin number

Default Tools & Configuration

Build and upload settings for TTGO T-Call (LilyGO)

Setting	Value
Bootloader tool	esptool_py
Uploader tool	esptool_py
Network uploader tool	esp_ota
Bootloader address	`0x1000`
Flash mode	dio
Boot mode	dio
Maximum upload size	1280 KB (1310720 bytes)
Maximum data size	320 KB (327680 bytes)