From e5cdda9ee5c993efd5b39f5c82b81458e98534cd Mon Sep 17 00:00:00 2001
From: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Date: Wed, 12 Aug 2026 00:22:52 +1200
Subject: [PATCH] [adc] Fix RP2350B internal temperature reading wrong ADC
 channel (#18270)

---
 esphome/components/adc/adc_sensor_rp2.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/esphome/components/adc/adc_sensor_rp2.cpp b/esphome/components/adc/adc_sensor_rp2.cpp
index 6cb9ef113f..2732f5328b 100644
--- a/esphome/components/adc/adc_sensor_rp2.cpp
+++ b/esphome/components/adc/adc_sensor_rp2.cpp
@@ -52,7 +52,11 @@ float ADCSensor::sample() {
   if (this->is_temperature_) {
     adc_set_temp_sensor_enabled(true);
     delay(1);
-    adc_select_input(4);
+    // The on-die temperature sensor sits on the last ADC channel, and which one
+    // that is depends on the chip: input 4 on RP2040 and RP2350A, but input 8 on
+    // RP2350B, which has eight external channels instead of four. The SDK
+    // resolves it for the target being built, so do not hardcode it.
+    adc_select_input(ADC_TEMPERATURE_CHANNEL_NUM);
 
     for (uint8_t sample = 0; sample < this->sample_count_; sample++) {
       raw = adc_read();