Thank you friend. 
Your code is working. Data is sent to Home Assistant
1 Like
This is cool. I wasn’t aware of this approach. I think a lot of people get stuck with UART once you need a custom component.
I am not aware of this approach used anywhere else but that was my goal, find a way to help people read UART data without a custom component. It seems to be well suited for implementing simple UART devices where the code in the lambda would be 90% of the custom component code.
Key points are:
-
dummy_receiver: trueto make sure the debug logging gets triggered - the rx data is returned in
std::vector<uint8_t> bytes - delimiter and timeout tweaked so rx data is presented in consistent format
-
direction: RXif uart.write is used to tx data
3 Likes
Are you aware of any key differences in the two approaches such as performance or reliability?
The uart-logging-hack:
- doesn’t have a
setup()if you need to perform some initialization (esphome.on_boot could be work around) - is constrained to cases where the rx data packets can be handled by the uart debug after mapping
- only gets called when data arrives
I think reliability and performance should be similar between both approaches. The uart-logging-hack is only called when there is data to process but the framework is still checking and buffering the data in the background.
1 Like
I have problems with a very similar set-up which is a modified version of your suggestion to capture a Rx into the uart
[22:38:04][D][uart_debug:158]: <<< "1:4.12\n"
[22:38:08][D][uart_debug:158]: <<< "1:4.12\n"
[22:38:10][D][uart_debug:158]: <<< "1:4.12\n"
For some reason I think it is not being ‘captured’ by the if statement and the ‘batVol’ sensors don’t update when a message is received (I have adjusted names of variables from your example)
esphome:
name: "esp-now-hub-v1"
esp32:
board: esp32dev
framework:
type: arduino
# Enable logging
logger:
level: verbose
uart:
id: uart_bus
rx_pin: 16
tx_pin: 17
baud_rate: 115200
debug:
direction: BOTH
dummy_receiver: true
after:
delimiter: "\n"
sequence:
- lambda: UARTDebug::log_string(direction, bytes);
int sensorID=0;
float sensorBatVol=0;
std::string str(bytes.begin(), bytes.end());
//there are x sensors
//where<<< id:batteryvoltage
//"1:4.00\n"
if (sscanf(str.c_str(), "%d:%f", &sensorID, &sensorBatVol) == 2 ) {
if(sensorID==1) {
id(batvol1).publish_state(sensorBatVol);
}
if(sensorID==2) {
id(batvol2).publish_state(sensorBatVol);
}
if(sensorID==3) {
id(batvol3).publish_state(sensorBatVol);
}
if(sensorID==4) {
id(batvol4).publish_state(sensorBatVol);
}
}
# Enable Home Assistant API
api:
ota:
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
# Enable fallback hotspot (captive portal) in case wifi connection fails
ap:
ssid: "Esphome-Web-6Bdf8C"
password: "hnLdPNIUXUZq"
captive_portal:
sensor:
- platform: wifi_signal # Reports the WiFi signal strength/RSSI in dB
name: "WiFi Signal dB"
id: wifi_signal_db
update_interval: 60s
entity_category: "diagnostic"
- platform: copy # Reports the WiFi signal strength in %
source_id: wifi_signal_db
name: "WiFi Signal Percent"
filters:
- lambda: return min(max(2 * (x + 100.0), 0.0), 100.0);
unit_of_measurement: "Signal %"
entity_category: "diagnostic"
- platform: template
name: "Battery Voltage 1"
id: "batvol1"
update_interval: 5s
- platform: template
name: "Battery Voltage 2"
id: "batvol2"
- platform: template
name: "Battery Voltage 3"
id: "batvol3"
- platform: template
name: "Battery Voltage 4"
id: "batvol4"
button:
- platform: template
name: "Test Button 1"
on_press:
- uart.write: "1:4.1\n"
- platform: template
name: "Test Button 2"
on_press:
- uart.write: "1:2.2\n"
I also incorporated the test buttons and loop back wire. The test button creates the response at the Rx but again the sensorBatVol never updates.
Things to note:
There are only 2 arguments. the Sensor number and the Battery voltage
I only seen to have a /n in my message (even though I added a /r as well on the Tx of the message sending ESP32.
Also - have I amended this line correctly?
if (sscanf(str.c_str(), "%d:%f", &sensorID, &sensorBatVol) == 2 ) {
btw just to add a bit more information. This is the write statement to the sending ESP 32 Tx port
Serial2.write("1:4.12", 6); // write data to serial port for onward transmission to Home Assistant
Serial2.write('\r\n');
I should be able to work this out but it’s got me beat! 
ah ha found the error. It was formatting
I changed this:
- lambda: UARTDebug::log_string(direction, bytes);
int sensorID=0;
to this:
- lambda: |-
UARTDebug::log_string(direction, bytes);
int sensorID=0;
Clearly it makes a difference!
1 Like
Hi.
I’m trying to use your code to extract specific values from the string received by UART.
I receive this string:
57,67,251,0,1,0,31,249
I would like to get the first two values from this string and add them to the HA entity.
Will you help?
Take a look at this post for some more general examples. Assuming you want the first two values in HA as numeric sensors, modify the section with sscanf to extract the first two values. Example was changed to use comma as delimiter between the values. The ==2 make sure sscanf reads two values.
//Sample uart text protocol
if (sscanf(str.c_str(), "%d,%d", &val1, &val2) == 2 ) {
id(sensor1).publish_state(val1);
id(sensor2).publish_state(val2);
}
2 Likes
The code probably works but not entirely correctly.
Code:
sequence:
- lambda: |-
UARTDebug::log_int(direction, bytes,',');
int val1=0;
int val2=0;
std::string str(bytes.begin(), bytes.end());
if (sscanf(str.c_str(), "%d,%d", &val1, &val2) == 2 ) {
id(sensor1).publish_state(val1);
id(sensor2).publish_state(val2);
}
sensor:
- platform: template
name: "KOCIOŁ"
unit_of_measurement: "°C"
id: "sensor1"
- platform: template
name: "ZASOBNIK C.W.U."
unit_of_measurement: "°C"
id: "sensor2"
And these two entities in HA still have the “unknown” status
How do the ESPHOME logs look?
Is this from UARTDebug::log_string or UARTDebug::log_int? If it is log_int then you would just need this in the debug lambda:
UARTDebug::log_int(direction, bytes,',');
id(sensor1).publish_state( bytes[0] );
id(sensor2).publish_state( bytes[1]);
The log_string debug output treats the received byte vales as the ASCII index for each character. For the log_int, it prints the byte values received formatted as integers.
Amazing, it works perfectly.
Thank you very much.
1 Like
Hi Gents,
@mulcmu this is a very old post with a very smart solution, that’s awesome!
You saved my day!
Best,
Luca
1 Like
hi all
can someone tell me what is wrong with my code ?
esp dont put values in templates , rawstring is ok
my code:
uart:
baud_rate: 9600
tx_pin: GPIO17
rx_pin: GPIO16
debug:
direction: RX
dummy_receiver: true
after:
delimiter: "\n\r"
sequence:
- lambda: |-
UARTDebug::log_string(direction, bytes);
std::string str(bytes.begin(), bytes.end());
id(rawString).publish_state(str.c_str());
float sensors_values0 =0;
float sensors_values1 =0;
float sensors_values2 =0;
if (sscanf(str.c_str(), "%f;%f;%f", &sensors_values0, &sensors_values1, &sensors_values2) == 3 ) {
id(tempA1).publish_state(sensors_values0);
id(tempA2).publish_state(sensors_values1);
id(tempA3).publish_state(sensors_values2);
}
sensor:
- platform: template
name: "A1"
id: "tempA1"
- platform: template
name: "A2"
id: "tempA2"
- platform: template
name: "A3"
id: "tempA3"
thanks
The sscanf format string %f is for base10 numeric floating point values. The first value in your input “AA” can’t be converted. If it is a hexadecimal value then you can use %x.
thank you , it works fine .
does it change a lot if first value in input is “SR”
second problem : how in lambda check if first input is “AA” or “SR”
%s will read in a string. If you only have the two options “AA” or “SR” you could do two sscanf() statements with “AA;%f;%f” and “SR;%f;%f”
I’m trying to send and receive data from an ESP32 to an Arduino Mega via UART.
Sending goes from the ESP to the Mega in the direction of Mega.
I can see that in the Mega log and in the ESP log.
When data is sent from the Mega, I can still see it in the serial monitor in the Mega but nothing arrives in the ESP, at least that’s what it looks like.
Can someone please help me?
her is the Arduino-Mega Serial-Output.
first lines is from ESP-restart.
12:34:08.518 -> Empfangen vom ESP : [878781][D][Updater.cpp:133] begin(): OTA Partition: app0
12:34:20.850 -> Empfangen vom ESP : [891108][V][WiFiGeneric.cpp:360] _arduino_event_cb(): STA Disconnected: SSID: ASUS, BSSID: 40:b0:76:9a:4d:70, Reason: 8
12:34:20.881 -> Empfangen vom ESP : [891108][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino EvenCONNECTED
12:34:20.881 -> Empfangen vom ESP : [891115][W][WiFiGeneric.cpp:950] _eventCallback(): Reason: 8 - 3][V][WiFiGeneric.cpp:341] _arduino_event_cb(): STA Stopped
12:34:21.213 -> Empfangen vom ESP : [891128][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino Even[ 753][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino Event: 0 - WIFI_READY
12:34:21.213 -> Empfangen vom ESP : [ 786][V][WiFiGeneric.cpp:338] _arduino_event_cb(): STA Started
12:34:21.248 -> Empfangen vom ESP : [ 787][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino Event: 2 - STA_START
12:34:27.149 -> Empfangen vom ESP : [ 6710][V][WiFiGeneric.cpp:381] _arduino_event_cb(): SCAN Done: ID: 128, Status: 0, Results: 9
12:34:27.149 -> Empfangen vom ESP : [ 6710][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino Event: 1 - SCAN_DONE
12:34:28.017 -> Empfangen vom ESP : [ 7558][V][WiFiGeneric.cpp:353] _arduino_event_cb(): STA Connected: SSID: ASUS, BSSID: 40:b0:76:9a:4d:70, Channel: 10, Auth: WPA2_PSK
12:34:28.017 -> Empfangen vom ESP : [ 7559][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino Even][V][WiFiGeneric.cpp:367] _arduino_event_cb(): STA Got New IP:192.168.2.119
12:34:28.061 -> Empfangen vom ESP : [ 7574][D][WiFiGeneric.cpp:929] _eventCallback(): Arduino EvenFiGeneric.cpp:991] _eventCallback(): STA IP: 192.168.2.119, MASK: 255.255.255.0, GW: 192.168.2.1
12:36:47.411 -> Empfangen vom ESP :
12:38:17.789 -> Empfangen vom ESP : DataToSend from button esp
12:38:44.242 -> Nachricht Serial.print von Mega To Esp: dd
The last lines 12:38:17.789 , was i pressed the button on the ESP
The last line shows a manual input from me on the Arduino Mega’s serial monitor
The Logfile from ESP32 (ESP32-S2-DevKit-M-1)
[12:34:30][I][app:100]: ESPHome version 2024.10.3 compiled on Nov 19 2024, 12:32:50
[12:34:30][C][wifi:600]: WiFi:
[12:34:30][C][wifi:428]: Local MAC: 70:04:1D:FB:D9:DA
[12:34:30][C][wifi:433]: SSID: [redacted]
[12:34:30][C][wifi:436]: IP Address: 192.168.2.119
[12:34:30][C][wifi:440]: BSSID: [redacted]
[12:34:30][C][wifi:441]: Hostname: 'watercontroltest'
[12:34:30][C][wifi:443]: Signal strength: -46 dB ▂▄▆█
[12:34:30][V][wifi:445]: Priority: 0.0
[12:34:30][C][wifi:447]: Channel: 10
[12:34:30][C][wifi:448]: Subnet: 255.255.255.0
[12:34:30][C][wifi:449]: Gateway: 192.168.2.1
[12:34:30][C][wifi:450]: DNS1: 192.168.2.1
[12:34:30][C][wifi:451]: DNS2: 0.0.0.0
[12:34:30][C][logger:185]: Logger:
[12:34:30][C][logger:186]: Level: VERBOSE
[12:34:30][C][logger:188]: Log Baud Rate: 115200
[12:34:30][C][logger:189]: Hardware UART: USB_CDC
[12:34:30][C][uart.arduino_esp32:151]: UART Bus 0:
[12:34:30][C][uart.arduino_esp32:152]: TX Pin: GPIO44
[12:34:30][C][uart.arduino_esp32:153]: RX Pin: GPIO45
[12:34:30][C][uart.arduino_esp32:155]: RX Buffer Size: 256
[12:34:30][C][uart.arduino_esp32:157]: Baud Rate: 115200 baud
[12:34:30][C][uart.arduino_esp32:158]: Data Bits: 8
[12:34:30][C][uart.arduino_esp32:159]: Parity: NONE
[12:34:30][C][uart.arduino_esp32:160]: Stop bits: 1
[12:34:30][C][uart.button:014]: UART Button 'UART String Output'
[12:34:30][C][captive_portal:089]: Captive Portal:
[12:34:30][C][web_server:153]: Web Server:
[12:34:30][C][web_server:154]: Address: 192.168.2.119:80
[12:34:30][C][mdns:116]: mDNS:
[12:34:30][C][mdns:117]: Hostname: watercontroltest
[12:34:30][V][mdns:118]: Services:
[12:34:30][V][mdns:120]: - _esphomelib, _tcp, 6053
[12:34:30][V][mdns:122]: TXT: friendly_name = WaterControler_test
[12:34:30][V][mdns:122]: TXT: version = 2024.10.3
[12:34:30][V][mdns:122]: TXT: mac = 70041dfbd9da
[12:34:30][V][mdns:122]: TXT: platform = ESP32
[12:34:30][V][mdns:122]: TXT: board = esp32-s2-saola-1
[12:34:30][V][mdns:122]: TXT: network = wifi
[12:34:30][V][mdns:122]: TXT: api_encryption = Noise_NNpsk0_25519_ChaChaPoly_SHA256
[12:34:30][V][mdns:120]: - _http, _tcp, 80
[12:34:30][C][esphome.ota:073]: Over-The-Air updates:
[12:34:30][C][esphome.ota:074]: Address: 192.168.2.119:3232
[12:34:30][C][esphome.ota:075]: Version: 2
[12:34:30][C][esphome.ota:078]: Password configured
[12:34:30][C][safe_mode:018]: Safe Mode:
[12:34:30][C][safe_mode:020]: Boot considered successful after 60 seconds
[12:34:30][C][safe_mode:021]: Invoke after 10 boot attempts
[12:34:30][C][safe_mode:023]: Remain in safe mode for 300 seconds
[12:34:30][C][api:140]: API Server:
[12:34:30][C][api:141]: Address: 192.168.2.119:6053
The ESPhome-Code
uart:
tx_pin: GPIO44
rx_pin: GPIO45
id: uart_bus
baud_rate: 115200
debug:
direction: BOTH
dummy_receiver: true
#after:
# delimiter: "\n"
sequence:
- lambda: UARTDebug::log_string(direction, bytes);
button:
- platform: uart
name: "UART String Output"
data: 'DataToSend from button esp'
#custom_component:
#- lambda: |-
# auto my_custom = new MyCustomComponent(id(uart_bus));
# return {my_custom};
captive_portal:
sorry all, now works fine… i used the wrong RX/TX Pins…