Hardware notes

Schematics

The original schematics, BOM and Gerber files can be found at https://oshwhub.com/sunnygold/esp32s3-si4732-shou-yin-ji. A copy of the files is available at https://github.com/esp32-si4732/esp32-si4732-oshwhub

No schematics available for other PCB versions currently sold, but you can find a brief overview here.

Datasheets

  • ESP32-S3-WROOM-1 1, 2 - MCU SoC

  • SI4732-A10 1, 2, 3, 4, 5 - broadcast radio receiver

  • ST7789 - LCD controller (also see the GC9307-XL caveat)

  • GC9307 - LCD controller

  • NS4160 - audio amplifier

  • AD4150B - audio amplifier

  • ME6217 - LDO regulator

  • TP4056 - battery charge controller

Pinout

The pinout table is shown below.

The relevant columns are ESP32-S3-WROOM-1 “Pin Name” and “ATS-Mini Sketch Pin Definitions”

ESP32-S3-WROOM-1
Pin #

ESP32-S3-WROOM-1
Pin Name

ATS-MINI Sketch
Pin Definitions

TFT_eSPI
Pin Definition

xtronic.org
Schematic

Comments
Info

1

GND

GND

2

3V3

VCC_33

3

EN

EN

RST Button

4

IO4

VBAT_MON

BAT_ADC

Battery monitor

5

IO5

TFT_RST

LCD_RES

6

IO6

TFT_CS

LCD_CS

7

IO7

TFT_DC

LCD_DC

8

IO15

PIN_POWER_ON

RADIO_EN

1= Radio LDO Enable

9

IO16

RESET_PIN

RST

SI4732 Reset

10

IO17

ESP32_I2C_SCL

I2C_SCL

SI4732 Clock

11

IO18

ESP32_I2C_SDA

I2C_SDA

SI4732 Data

12

IO8

TFT_WR

LCD_WR

13

IO19

USB_DM

USB_D- (CDC Port)

14

IO20

USB_DP

USB_D+ (CDC Port)

15

IO3

AUDIO_MUTE

MUTE

1 = Mute L/R audio

16

IO46

TFT_D5

LCD_DS

17

IO9

TFT_RD

LCD_RD

18

IO10

PIN_AMP_EN

AMP_EN

1 = Audio Amp Enable

19

IO11

NC

Spare

20

IO12

NC

Spare

21

IO13

NC

Spare

22

IO14

NC

Spare

23

IO21

ENCODER_PUSH_BUTTON

SW

Rotary encoder SW signal

24

IO47

TFT_D6

LCD_D6

25

IO48

TFT_D7

LCD_D7

26

IO45

TFT_D4

LCD_D4

27

IO0

GPIO0

BOOT button

28

IO35

NC

Used for OSPI PSRAM

29

IO36

NC

Used for OSPI PSRAM

30

IO37

NC

Used for OSPI PSRAM

31

IO38

PIN_LCD_BL

TFT_BL

LCD_BL

Backlight control

32

IO39

TFT_D0

LCD_D0

33

IO40

TFT_D1

LCD_D1

34

IO41

TFT_D2

LCD_D2

35

IO42

TFT_D3

LCD_D2

36

RXD0

NC

GPIO44

37

TXD0

NC

GPIO43

38

IO2

ENCODER_PIN_A

A

Rotary encoder A signal

39

IO1

ENCODER_PIN_B

B

Rotary encoder B signal

40

GND

GND

41

EPAD

GND

BOOT and RESET buttons

Some of the ESP32-SI4732 receivers do not have the BOOT and RESET buttons soldered in. You will need these buttons if you want to recover a receiver that was bricked because of a failed flashing process. Here is how to add the BOOT & RESET buttons.

LILYGO T-Embed SI4732

Impressions so far:

  • Due to the lack of a power switch, the stock firmware uses deep sleep, triggered by a long press, but it still drains the battery. The ATS Mini firmware already uses the long-press gesture for other purposes, so there is no way to turn the receiver off.

  • The reset button is external, and the boot button is combined with the encoder button. This makes triggering bootloader mode much easier, but it also means that to reset the receiver settings, you have to press and hold the encoder button right after powering the receiver on, not before.

  • The display is connected via SPI, but the MISO pin is used for different purposes. This means the display controller registers are write-only.

  • The display color palette is a bit off, so the themes look different.

  • There are separate FM and AM antenna connectors on the SI4732 board.

  • The encoder is nice, but the push-and-rotate gesture is harder to use.

  • There is no headphone jack.

  • The speaker is on the top.

  • The antenna connector on the back cover can be used as a stand to tilt the receiver back.

It is highly recommended to do a little hardware mod and install a physical power switch (without it you won’t be able to switch the receiver off after you flash the ATS Mini firmware):

Links: