Huge thanks again to everyone doing the heavy lifting on the XYE interface. I have a bit of a breakthrough on the concealed-duct unit I described in post #97, and I wanted to put the full result back here instead of just saying “it works.”
For context, this is an ACiQ/Midea 24K concealed-duct AHU on a 6-zone condenser. I have an M5Stack Atom + Tail485 on XYE at 4800 baud, while the KJR-120N wired controller is still attached on its separate controller bus.
What I’ve proved
- The head reports capabilities
0x14, so it does not advertise the EXTERNAL_TEMP capability (0x80).
- The ESPHome component sends the C6 Follow-Me frame successfully, but this particular head ignores it.
- I heated the wired thermostat with a heat gun. Its reported temperature climbed to about 89°F while the independent living-room sensor stayed around 72°F, and the unit continued regulating against the wired thermostat temperature.
- Setpoint writes sent over XYE are accepted, echoed back, and remain authoritative even with the wired controller attached.
So native C6 Follow-Me is a dead end on this head, but XYE setpoint control gives us another path.
The fallback that is working
Every 60 seconds the ESP32 calculates:
head setpoint = desired room target + (wired thermostat temperature - independent room temperature)
Example: if I want the room at 70°F, the wall controller sees 73°F, and the room sensor sees 71°F, the ESP32 sends a 72°F setpoint to the head. As those two measured temperatures converge, the bias disappears.
The loop is on the ESP32, so it does not depend on a Home Assistant automation continuing to run. It exits when the climate is off, skips invalid sensor values, clamps the command to 65–78°F, and has a switch that disables room tracking immediately. A live result looked like this:
target=70.0F wall=22.8C room=22.4C -> setpoint=70.7F
The unit echoed the setpoint and held it. The independent room sensor was also within about 0.4°F of a separate handheld reading.
I am not claiming the underlying offset math is new control theory. What may be useful/novel here is applying a continuously recalculated two-sensor bias on-device as a software Follow-Me fallback for an XYE head that transmits and receives normally but ignores C6. I found the static-offset discussion in #38, the fake Follow-Me idea in #140 and #147, and manual setpoint-offset tuning in #150, but I did not find this exact fallback. If somebody already published it, please point me there.
Important caveats
- This is validated on one ACiQ concealed-duct head, primarily in cooling. Different unit families and controller-bus topologies may behave differently.
- I still want to add a minimum-change threshold and an explicit stale-room-sensor timeout before calling the loop finished.
- The working component is currently a local vendor:
larsonm-personal@62a3047 for the raw-Fahrenheit/C0 behavior, plus the WAIT_DATA recovery from HomeOps PR #136. The raw-Fahrenheit/C0 work is still represented publicly by HomeOps PR #137, so the upstream pieces are split at the moment.
- The YAML below therefore references a local
components/midea_xye directory; it is the complete configuration I am running, but that local component directory is also required to compile it.
If anyone has a head without EXTERNAL_TEMP, or sees valid C6 frames being sent but ignored, I would really like another data point.
Full working ESPHome configuration
substitutions:
name: livingroom-hvac
friendly_name: "Living Room HVAC"
comment: "ESPHome flashed M5Stack Atom with Tail485 attached to livingroom/kitchen AHU in attic"
esphome:
name: ${name}
name_add_mac_suffix: false
friendly_name: ${friendly_name}
comment: ${comment}
esp32:
board: esp32dev
framework:
type: arduino
# Enable logging (but not via UART)
logger:
#baud_rate: 0
#logs:
# component: ERROR
# Enable Home Assistant API
api:
encryption:
key: !secret api_key
# services:
# - service: follow_me
# variables:
# temperature: float
# then:
# midea_ac.follow_me:
# temperature: !lambda "return temperature;"
# beeper: false
# Enable wifi
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
use_address: 192.168.1.236
# url: https://github.com/exciton/esphome
external_components:
# #942 (2026-07-11): switched from the pinned git source to a LOCAL vendored
# copy of the larsonm-personal @62a3047 (ch_concealed) midea_xye component so
# we could patch the WAIT_DATA deadlock. That build has the correct C&H/ACiQ
# raw-Fahrenheit decode (temperature_encoding: RAW + target_temperature_source:
# C0; wire-proven 0x46=70degF) but NO recovery from a missed/short/over-long
# reply — one glitched response permanently strands the poll loop (all bus
# telemetry silently freezes; current_temperature/target go null while the ESP
# stays healthy). This regressed the bring-up ~2 days after it went live.
# The vendored copy under components/midea_xye/ backports HomeOps upstream
# main's recovery path into climate_midea_xye.cpp's no-reply branch (see the
# #942 comment there). Everything else is byte-identical to @62a3047.
#
# History: mdrobnak@delays_updated (original deadlock, dead 100ms timeout) ->
# larsonm-personal @62a3047 (raw-degF decode, deadlock still present) ->
# this local vendored + patched copy (raw-degF decode + deadlock recovery).
#
# UPSTREAM EXIT: when the raw-Fahrenheit decode (temperature_encoding: RAW /
# target_temperature_source: C0) lands in a HomeOps release that ALSO carries
# the recovery path, delete homeassistant/esphome/components/midea_xye/ and
# repoint this block to that release tag.
- source:
type: local
path: components
components: [midea_xye]
#i2c settings for dfrobot MiCS-4514 gas sensor
i2c:
sda: GPIO25
scl: GPIO21
scan: true
id: bus_a
# UART settings for RS485 converter dongle (required)
uart:
tx_pin: GPIO26
rx_pin: GPIO32
baud_rate: 4800
rx_buffer_size: 1024
# #942 diagnostics: log both directions, chunked at the XYE prologue 0x55.
# Capture C0-RX byte 10 (setpoint) + 11 (T1) vs known values to settle the
# raw-Fahrenheit variant (PROTOCOL.md Temperature Encoding; HomeOps#137).
debug:
direction: BOTH
after:
delimiter: [0x55]
# debug: #If you want to help reverse engineer
# direction: BOTH
#dummy_receiver: true
#after:
# delimiter: [0x55]
# Enable esphome OTA updates
ota:
password: !secret ota_password
id: my_ota
platform: esphome
# Main settings
climate:
- platform: midea_xye
name: Living Room HVAC
id: midea_ac
period: 1s # Optional. Defaults to 1s
timeout: 300ms # #942: honored on HomeOps; generous vs ~67ms frame time
beeper: false # Optional. Beep on commands.
#default_target_temperature_low: 18°C
#default_target_temperature_high: 24°C
#custom_auto: true
use_fahrenheit: true
temperature_encoding: RAW # #942: unit sends raw degF bytes (wire-proven)
target_temperature_source: C0 # #942: unit lacks C4 (all-0xFF sentinel)
compressor_aware_action: true # #942 batch: hvac_action reflects real compressor state
sync_fan_mode_from_device: true # #942 batch: head-unit fan changes reflect into HA
# #1021: native XYE follow-me is INERT on this head — the heat-gun test proved
# it regulates to the WALL THERMOSTAT (internal_current_temperature) and
# ignores external follow-me (capability 0x14, no EXTERNAL_TEMP). Room-based
# control is done on-device via the SETPOINT-BIAS loop (see the number:/
# switch:/interval: blocks below), so the follow_me_sensor binding is removed.
visual: # Optional. Example of visual settings override.
min_temperature: 65 °F # min: 17
max_temperature: 78 °F # max: 30
temperature_step: 0.5 °F # min: 0.5
# visual: # Optional. Example of visual settings override.
# min_temperature: 17 °C # min: 17
# max_temperature: 30 °C # max: 30
# temperature_step: 0.5 °C # min: 0.5
supported_modes: # Optional.
- FAN_ONLY
- HEAT_COOL
- COOL
- HEAT
- DRY
supported_presets: # Optional
- BOOST
# outdoor_temperature: DISABLED (#942 cleanup) — this AHU never populates
# the field (C4 response is all-0xFF sentinel; the value rendered as
# -4degF pre-RAW and ~0degF post-RAW, both meaningless). Re-enable only
# if the unit ever gains an ODU on the bus.
temperature_2a: # Optional. Inside coil temperature
name: Inside Coil Inlet Temp
temperature_3:
name: Outside Coil Temperature
timer_start: # Optional. On timer duration
name: Timer Start
timer_stop: # Optional. Off timer duration
name: Timer Stop
error_flags: # Optional.
name: Error Flags
protect_flags: # Optional.
name: Protect Flags
static_pressure:
name: Static Pressure
min_value: 0
# #942 batch (2026-07-09): duty/diagnostic surface
fan_speed:
name: Fan Speed
internal_current_temperature: # = the WALL THERMOSTAT reading the head
name: Internal Current Temperature # regulates to (heat-gun-proven, #1021);
id: head_wall_temp # °C internally (HA shows °F). Bias ref.
internal_target_temperature:
name: Internal Target Temperature
defrost:
name: Defrost
compressor_active: # the duty-cycle signal (A/B-correlation class)
name: Compressor Active
button:
# #942: manual unwedge affordance (and future automation hook if the
# component ever freezes again — restart clears any wedged state).
- platform: restart
name: Living Room HVAC Restart
number:
# #1021 setpoint-bias: the DESIRED ROOM temperature (°F). HA / your schedules
# set this one value; the interval loop below drives the head's setpoint so the
# ROOM converges here. Plain number (no device_class) so HA does not unit-convert
# it — the value is °F as typed and the loop converts to °C.
- platform: template
name: "Living Room Room Target"
id: room_target
unit_of_measurement: "°F"
min_value: 65
max_value: 78
step: 0.5
initial_value: 72
restore_value: true
optimistic: true
mode: box
switch:
# #1021 setpoint-bias: room-tracking on/off. OFF = climate behaves normally
# (setpoint is whatever you/the wall set). ON = the interval loop overrides the
# head's setpoint every 60s to track Room Target. Default OFF until validated.
- platform: template
name: "Living Room Room Tracking"
id: room_tracking
optimistic: true
restore_mode: RESTORE_DEFAULT_OFF
interval:
# #1021 setpoint-bias loop. Every 60s, when Room Tracking is ON and the head is
# not OFF: head_setpoint = Room Target + (wall_thermostat − room_sensor)
# so the head cools/heats until ITS reference (the wall thermostat) hits the
# biased target, at which point the ROOM reads Room Target. wall_thermostat =
# internal_current_temperature (heat-gun-proven; °C in ESPHome). All math in °C;
# set_target_temperature() takes °C. FAIL-SAFE: skip if any input is NaN (e.g.
# the room sensor went stale) — the head just holds its last setpoint. Clamp to
# the head's safe range (65–78 °F).
- interval: 60s
then:
- lambda: |-
if (!id(room_tracking).state) return;
if (id(midea_ac).mode == climate::CLIMATE_MODE_OFF) return;
float wall_c = id(head_wall_temp).state; // wall thermostat (°C)
float room_c = id(room_temp_c).state; // room sensor (°C)
float tgt_c = (id(room_target).state - 32.0f) * (5.0f/9.0f);// desired room °F→°C
if (isnan(wall_c) || isnan(room_c) || isnan(tgt_c)) return; // fail-safe
float sp_c = tgt_c + (wall_c - room_c); // biased setpoint (°C)
const float lo = (65.0f - 32.0f) * (5.0f/9.0f); // 65 °F
const float hi = (78.0f - 32.0f) * (5.0f/9.0f); // 78 °F
if (sp_c < lo) sp_c = lo;
if (sp_c > hi) sp_c = hi;
auto call = id(midea_ac).make_call();
call.set_target_temperature(sp_c);
call.perform();
ESP_LOGI("setpoint_bias", "target=%.1fF wall=%.1fC room=%.1fC -> setpoint=%.1fC (%.1fF)",
id(room_target).state, wall_c, room_c, sp_c, sp_c * 9.0f/5.0f + 32.0f);
sensor:
# #1021 setpoint-bias: the operator-installed room sensor, imported from HA
# (°F) and converted to °C — the "room" term of the on-device bias loop.
# internal:true — it's a loop input, not a new HA entity (the original HA
# sensor sensor.living_room_temperature_temperature stays the display).
- platform: homeassistant
entity_id: sensor.living_room_temperature_temperature
id: room_temp_c
internal: true
filters:
- throttle: 15s
- heartbeat: 60s
- debounce: 2s
- lambda: return (x - 32.0) * (5.0/9.0); # °F → °C (ESPHome climate is °C)
- platform: wifi_signal
name: Living Room HVAC Wi-Fi Signal
update_interval: 60s
- platform: uptime
name: "Uptime"
id: uptime_sec
internal: true
- platform: template
name: Living Room HVAC Uptime Days
lambda: |-
return (id(uptime_sec).state/60)/60/24;
icon: mdi:clock-start
unit_of_measurement: days
update_interval: 60s
- platform: mics_4514
i2c_id: bus_a
address: 0x75
nitrogen_dioxide:
name: Nitrogen Dioxide
carbon_monoxide:
name: Carbon Monoxide
hydrogen:
name: Hydrogen
ethanol:
name: Ethanol
methane:
name: Methane
ammonia:
name: Ammonia
update_interval: 60s
