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esp32_sensor_module - Build Notes

Overview

Dual ESP32-WROOM-32 bare module PCB (130×80mm) for engine ECU sensor interface (example: Toyota 5S-FE) interface (J5) + body controller with ULN2003A relays (J6).

Circuits

  • 6× voltage dividers (5.6K+10K THT axial) for: PIM, THW, VTA, SPD, IGf, T/VF
  • 2× 120Ω pullups for fuel level & oil pressure senders
  • 4× 10K series resistors for door/hood/trunk GND-switch inputs
  • 2× 2N2222 + 1K base R for TE1/TE2 DTC reading
  • 1× 10K pulldown on GPIO39 (VN) for ADC crosstalk prevention
  • DC-DC converter from 12V → 3.3V
  • 2× ULN2003A DIP-16 relay drivers (10 channels)
  • Flyback diodes (9× 1N4007) for relay coil suppression

J5 Sensor WROOM-32 Signal Map (J5)

Signal GPIO Module Pin
DRV 13 20
PASS 14 29
TVF 19 8
HOOD 21 6
TE1 22 3
TE2 23 2
SPD 25 26
IGF 26 27
TRUNK 27 28
PIM 32 30
THW 33 31
VTA 34 34
FUEL 35 33
OIL 36 36
VN_PD 39 35

J6 Body WROOM-32 Signal Map (J6)

Signal GPIO Module Pin
HVAC 2 15
AC 4 13
REMOTE 5 10
FAN2 12 24
FAN1 18 9
BTN_SEL 22 3
BTN_EXIT 23 2
DOOR_LOCK 25 26
WINDOW_UP 26 27
WINDOW_DOWN 27 28
EXTRA1 32 30
EXTRA2 33 31
JOY_Y 36 36
JOY_X 39 35

ESP32-WROOM-32 Module Pinout (38-pin castellated)

Pin Function
1 GND
2 GPIO23
3 GPIO22
4 GPIO1(TXD)
5 GPIO3(RXD)
6 GPIO21
7 GND
8 GPIO19
9 GPIO18
10 GPIO5
11 GPIO17
12 GPIO16
13 GPIO4
14 GPIO0
15 GPIO2
16 GPIO15
17 GPIO8
18 GPIO7
19 GPIO6
20 GPIO13
21 GPIO9(SD2)
22 GPIO10(SD3)
23 GPIO11(CMD)
24 GPIO12
25 VDD
26 GPIO25
27 GPIO26
28 GPIO27
29 GPIO14
30 GPIO32
31 GPIO33
32 GND
33 GPIO35
34 GPIO34
35 GPIO39(VN)
36 GPIO36(VP)
37 EN
38 NC

Pins 1-15 = left column (closer to USB, with USB up). Pins 16-30 = right column (away from USB). GPIOs not on headers: 6,7,8,9,10,11 (internal flash). Strapping: GPIO0,2,5,12,15 — boot-sensitive. Input-only: GPIO34,35,36(VP),39(VN).

Power

  • Input: 12V from ECU +B (fused F1 1A) via J4
  • DC-DC: 12V→3.3V (U1), feeds all pullups and circuits
  • DevKit V1 power: Via USB, or jumper from PCB 3.3V rail to DevKit's 3V3 pin
  • Filtering: C1/C3 (0.1µF) + C2/C4 (10µF) per module region
  • Ground: Common ground, bottom layer pour recommended

Board Details

  • Size: 130×80mm
  • Layers: 2 (signal + GND pour on bottom)
  • Thickness: 1.6mm FR-4
  • Mounting: 4× M3 holes at corners
  • Cu weight: 1oz (2oz recommended for high-current)
  • Tracks: 0.25mm clearance, 0.6mm via dia, 0.3mm via drill

Notes

  • GPIOs 34/35/36/39 are input-only (no pullups internally).
  • ULN2003A COM pin (9) → +12V for internal flyback diodes.
  • Strapping pins on body module: GPIO2(HVAC), GPIO5(REMOTE), GPIO12(FAN2) — ensure peripherals don't interfere with boot.