ESP32 CYD ST7796 3.5 inches display: Pins

This page talks about the pins on the CYD. Back to the device overview

Connector types

Connector	Type	Note
P1	4P 1.25mm JST	Serial
P3	4P 1.25mm JST	GPIO
P4	2P 1.25mm JST	Speaker
CN1	4P 1.25mm JST	GPIO (I2C)
Battery	2P 1.25mm JST	Battery

What pins are available on the CYD?

There are 3 easily accessible GPIO pins

Pin	Location	Note
IO35	P3 JST connector	Input only pin, no internal pull-ups available
IO22	P3 and CN1 JST connector
IO21	CN1 JST connector

If you need more than that, you need to start taking them from something else. An SD Card sniffer like mentioned in the Add-ons is probably the next easiest.

After that you’re probably de-soldering something!

Broken Out Pins

There are three 4P 1.25mm JST connectors on the board

P3

|Pin|Use|Note| |—|—|—-| |GND||| |IO35||Input only pin, no internal pull-ups available | |IO22||Also on the CN1 connector | |IO21|| Also on the CN1 connector |

CN1

This is a great candidate for I2C devices

Pin	Use	Note
GND
IO22		Also on P3 connector
IO21		Also on P3 connector
3.3V

P1

|Pin|Use|Note| |—|—|—-| |VIN| 5V || |TX| IO1(?) | Maybe possible to use as a GPIO? | |RX | IO3(?)| Maybe possible to use as a GPIO? | |GND|||

Buttons

The CYD has three buttons, reset, boot and switch 1.

Pin	Use	Note
IO0	BOOT	Can be used as an input in sketches

The behavior of switch 1 is unknown.

Speaker

The speaker connector is a 2P 1.25mm JST connector that is connected to the amplifier, so not usable as GPIO at the speaker connector

Pin	Use	Note
IO26	Connected to amp	`i2s_set_dac_mode(I2S_DAC_CHANNEL_LEFT_EN);`

Battery

The battery connector is a 2P 1.25mm JST connector that is connected to the LiIon load control.

RGB LED

If your project requires additional pins to what is available elsewhere, this might be a good candidate to sacrifice.

Note: LEDs are “active low”, meaning HIGH == off, LOW == on

Pin	Use	Note
IO4	Red LED
IO16	Green LED
IO17	Blue LED

Display

Uses the HSPI

Pin	Use	Note
IO2	TFT_RS	AKA: TFT_DC
IO12	TFT_SDO	AKA: TFT_MISO
IO13	TFT_SDI	AKA: TFT_MOSI
IO14	TFT_SCK
IO15	TFT_CS
IO27	TFT_BL

Touch Screen

Pin	Use	Note
IO14	XPT2046_CLK
IO13	XPT2046_MOSI
IO33	XPT2046_CS
IO36	XPT2046_IRQ
IO12	XPT2046_MISO

SD Card

Uses the VSPI Pin names are predefined in SPI.h

Pin	Use	Note
IO5	SS (CS)
IO18	SCK
IO19	MISO
IO23	MOSI

LDR (Light Sensor)

Pin	Use	Note
IO34

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