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This DIY mmWave Presence Sensor Changed Everything - LD1125H How To Guide

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After searching through many mmWave sensors, some bad, some great, some expensive, I've landed on the LD1125G. An inexpensive sensor and stupid quick! In the video below I cover the testing process, building and installing open source ESPHome software on the ESP32. No cloud, no additional apps, and 100% local.

The use of a PIR has plagued my bathrooms from time to time with lights going out too early based on various activities in the bathroom. One cheat I did was to use the humidity sensor that drives the fan to force the light to be on when the humidity is high. This has worked well for the most part but I've been looking to fix the pain point in the smart home world for quite some time. I've finally found a sensor that works quick, easy to install and use. This has unlocked various new automations for the bathroom such as; turn on the vent if someone is in the bathroom for more than a minute or two, turn off the light once the person leaves and still allow the vent to run to pull down the humidity. Fully automating the light and fan in the bathroom may sound silly to some individuals but it is the thing that makes the home a true Smart Home and not use a remote controlled one.

Full Video

Wiring Diagram

alt text

Thanks Caleb for the awesome diagram! For a power source, I'm currently using a 5VDC power supply in my attic that powers many ESP based projects around the house in the walls, ceiling, etc.

What do you need?

*Affiliate Links

  1. mmWave LD1125G - Make sure to choose HLK-LD1125H-24G! or Aliexpress #2
  2. ESP32 NodeMCU Dev Board or ESP32 NodeMCU Dev Board
  3. 2.0mm to 2.54mm Pitch Female to Female Jumpers
  4. Optional BME280
  5. Optional USB Screw Terminals
  6. 5VDC Power Source

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ESPHome Code

Thanks to patrick3399 for his awesome YAML repo of Hi-Link mmWave sensors on Github

I've changed up a few things such as debug sensors, debug logs and added the BME280 sensors.

substitutions:
devicename: "esp32-mastbath"
upper_devicename: "esp32-mastbath"
update_time: 30s
esphome:
name: $devicename
on_boot: #LD1125H Initial Setting
priority: -200
then:
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th1st = "mth1=" + str_sprintf("%.0f",id(LD1125H_mth1).state) +"\r\n";
return std::vector<uint8_t>(th1st.begin(), th1st.end());
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th2st = "mth2=" + str_sprintf("%.0f",id(LD1125H_mth2).state) +"\r\n";
return std::vector<uint8_t>(th2st.begin(), th2st.end());
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th3st = "mth3=" + str_sprintf("%.0f",id(LD1125H_mth3).state) +"\r\n";
return std::vector<uint8_t>(th3st.begin(), th3st.end());
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string rmaxst = "rmax=" + str_sprintf("%.1f",id(LD1125H_rmax).state) +"\r\n";
return std::vector<uint8_t>(rmaxst.begin(), rmaxst.end());

i2c:
sda: GPIO19
scl: GPIO21
scan: True

esp32:
board: nodemcu-32s
framework:
type: esp-idf #Suggest Use ESP-IDF Framework, or Plug Out the UART Cable Might Cause ESP32 Hang.
external_components:
- source:
type: git
url: https://github.com/ssieb/custom_components #Thanks for @ssieb components.
components: [ serial ]
logger:
level: INFO #You Can Use "INFO" Level
baud_rate: 0
api:
ota:
platform: esphome
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
power_save_mode: LIGHT
# manual_ip:
# static_ip: !secret ip_esp32mastbath
# gateway: !secret ip_gateway
# subnet: !secret ip_subnet
# dns1: !secret ip_dns1
uart:
id: LD1125H_UART_BUS
rx_pin: GPIO16 #For ESP32, you can use any pin, Recommend Use UART_2, Don't use UART_0, It might Cause Boot Fail or System Hang
tx_pin: GPIO17 #For ESP32, you can use any pin, Recommend Use UART_2, Don't use UART_0, It might Cause Boot Fail or System Hang
# rx_pin: GPIO1 #For ESP32, you can use any pin, Recommend Use UART_2, Don't use UART_0, It might Cause Boot Fail or System Hang
# tx_pin: GPIO0 #For ESP32, you can use any pin, Recommend Use UART_2, Don't use UART_0, It might Cause Boot Fail or System Hang
baud_rate: 115200
data_bits: 8
stop_bits: 1
parity: NONE
# debug:
# direction: BOTH
# dummy_receiver: false
# after:
# delimiter: "\n"
# sequence:
# - lambda: UARTDebug::log_string(direction, bytes);
globals:
- id: LD1125H_Last_Time
type: time_t
restore_value: no
initial_value: time(NULL)
- id: LD1125H_Last_Mov_Time
type: time_t
restore_value: no
initial_value: time(NULL)
- id: LD1125H_Clearence_Status
type: bool
restore_value: no
initial_value: "false"
status_led:
pin:
number: GPIO2 #ESP32 OnBroad LED
inverted: false
#web_server: #Avoid Using Web Server To Prevent Hang
# port: 80
interval:
- interval: 1s #Clearance Scan Time
setup_priority: -200
then:
lambda: |-
if ((time(NULL)-id(LD1125H_Last_Time))>id(LD1125H_Clear_Time).state) {
if ((id(LD1125H_Clearence_Status) == false) || (id(LD1125H_Occupancy).state != "Clearance")) {
id(LD1125H_Occupancy).publish_state("Clearance");
id(LD1125H_Clearence_Status) = true;
}
if (id(LD1125H_MovOcc_Binary).state == true) {
id(LD1125H_MovOcc_Binary).publish_state(false);
}
if (id(LD1125H_Mov_Binary).state == true) {
id(LD1125H_Mov_Binary).publish_state(false);
}
}
number:
- platform: template
name: ${upper_devicename} LD1125H mth1 #mth1 is 0~2.8m Sensitivity.
id: LD1125H_mth1
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "60.0" #Default mth1 Setting
min_value: 10.0
max_value: 600.0
step: 5.0
set_action:
then:
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th1st = "mth1=" + str_sprintf("%.0f",x) +"\r\n";
return std::vector<uint8_t>(th1st.begin(), th1st.end());
- platform: template
name: ${upper_devicename} LD1125H mth2 #mth2 is 2.8~8m Sensitivity.
id: LD1125H_mth2
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "30" #Default mth2 Setting
min_value: 5
max_value: 300
step: 5
set_action:
then:
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th2st = "mth2=" + str_sprintf("%.0f",x) +"\r\n";
return std::vector<uint8_t>(th2st.begin(), th2st.end());
- platform: template
name: ${upper_devicename} LD1125H mth3 #mth3 is above 8m Sensitivity.
id: LD1125H_mth3
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "20" #Default mth3 Setting
min_value: 5
max_value: 200
step: 5
set_action:
then:
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string th3st = "mth3=" + str_sprintf("%.0f",x) +"\r\n";
return std::vector<uint8_t>(th3st.begin(), th3st.end());
- platform: template
name: ${upper_devicename} LD1125H rmax #rmax is max detection distance.
id: LD1125H_rmax
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "8" #Default rmax Setting
min_value: 0.4
max_value: 12
step: 0.1
set_action:
then:
- uart.write:
id: LD1125H_UART_BUS
data: !lambda |-
std::string rmaxst = "rmax=" + str_sprintf("%.1f",x) +"\r\n";
return std::vector<uint8_t>(rmaxst.begin(), rmaxst.end());
- platform: template
name: ${upper_devicename} LD1125H Clearence Time
id: LD1125H_Clear_Time
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "5" #LD1125H Mov/Occ > Clearence Time Here
min_value: 0.5
max_value: 20
step: 0.5
- platform: template
name: ${upper_devicename} LD1125H Movement Time
id: LD1125H_Mov_Time
icon: "mdi:cogs"
optimistic: true
restore_value: true #If you don't want to store the setting at ESP, set it to false.
initial_value: "1" #LD1125H Mov > Occ Time Here
min_value: 0.5
max_value: 10
step: 0.5
sensor:
- platform: bme280_i2c
temperature:
name: ${upper_devicename} BME280 Temp
accuracy_decimals: 1
oversampling: 2x
pressure:
name: ${upper_devicename} BME280 Pressure
oversampling: 2x
humidity:
name: ${upper_devicename} BME280 Humidity
accuracy_decimals: 1
oversampling: 2x
address: 0x76
update_interval: ${update_time}
# - platform: aht10
# temperature:
# accuracy_decimals: 2
# name: ${upper_devicename} AHT21 Temp
# humidity:
# accuracy_decimals: 2
# name: ${upper_devicename} AHT21 Humidity
# update_interval: ${update_time}
# - platform: wifi_signal
# name: ${upper_devicename} WiFi Signal
# update_interval: 60s
- platform: uptime
name: ${upper_devicename} Uptime
- platform: template
name: ${upper_devicename} LD1125H Distance
id: LD1125H_Distance
icon: "mdi:signal-distance-variant"
unit_of_measurement: "m"
accuracy_decimals: 2
filters: # Use Fliter To Debounce
- sliding_window_moving_average:
window_size: 8
send_every: 2
- heartbeat: 0.2s
text_sensor:
- platform: serial
uart_id: LD1125H_UART_BUS
name: ${upper_devicename} LD1125H UART Text
id: LD1125H_UART_Text
icon: "mdi:format-text"
internal: True #If Don't Want to See UART Receive Data, Set To True
on_value:
lambda: |-
if (id(LD1125H_UART_Text).state.substr(0,3) == "occ") {
id(LD1125H_Distance).publish_state(atof(id(LD1125H_UART_Text).state.substr(9).c_str()));
if ((time(NULL)-id(LD1125H_Last_Mov_Time))>id(LD1125H_Mov_Time).state) {
id(LD1125H_Occupancy).publish_state("Occupancy");
if (id(LD1125H_MovOcc_Binary).state == false) {
id(LD1125H_MovOcc_Binary).publish_state(true);
}
if (id(LD1125H_Mov_Binary).state == true) {
id(LD1125H_Mov_Binary).publish_state(false);
}
}
if (id(LD1125H_MovOcc_Binary).state == false) {
id(LD1125H_MovOcc_Binary).publish_state(true);
}
id(LD1125H_Last_Time) = time(NULL);
if (id(LD1125H_Clearence_Status) == true) {
id(LD1125H_Clearence_Status) = false;
}
}
else if (id(LD1125H_UART_Text).state.substr(0,3) == "mov") {
id(LD1125H_Distance).publish_state(atof(id(LD1125H_UART_Text).state.substr(9).c_str()));
id(LD1125H_Occupancy).publish_state("Movement");
if (id(LD1125H_MovOcc_Binary).state == false) {
id(LD1125H_MovOcc_Binary).publish_state(true);
}
if (id(LD1125H_Mov_Binary).state == false) {
id(LD1125H_Mov_Binary).publish_state(true);
}
id(LD1125H_Last_Mov_Time) = time(NULL);
id(LD1125H_Last_Time) = time(NULL);
if (id(LD1125H_Clearence_Status) == true) {
id(LD1125H_Clearence_Status) = false;
}
}
- platform: template
name: ${upper_devicename} LD1125H Occupancy Status
id: LD1125H_Occupancy
icon: "mdi:motion-sensor"
binary_sensor:
- platform: status
name: ${upper_devicename} Status
- platform: template
name: ${upper_devicename} LD1125H Occupancy or Movement
id: LD1125H_MovOcc_Binary
device_class: occupancy
- platform: template
name: ${upper_devicename} LD1125H Movement
id: LD1125H_Mov_Binary
device_class: motion