From d3b7b5d81b28601e833264f9f5e76b776d4b3b4f Mon Sep 17 00:00:00 2001
From: "Earle F. Philhower, III" <earlephilhower@yahoo.com>
Date: Mon, 4 Jan 2021 17:18:48 -0800
Subject: [PATCH] Add stub for analogReference

Fixes #6410

We actually provide a function prototype for `analogReference()` in
`Arduino.h`, but no implementation.  Add a dummy one that only supports
DEFAULT (like other Arduino boards).
---
 cores/esp8266/core_esp8266_wiring_analog.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/cores/esp8266/core_esp8266_wiring_analog.cpp b/cores/esp8266/core_esp8266_wiring_analog.cpp
index 27c98ff3f0..fe8d67e66e 100644
--- a/cores/esp8266/core_esp8266_wiring_analog.cpp
+++ b/cores/esp8266/core_esp8266_wiring_analog.cpp
@@ -39,4 +39,16 @@ extern int __analogRead(uint8_t pin)
 
 extern int analogRead(uint8_t pin) __attribute__ ((weak, alias("__analogRead")));
 
+
+void __analogReference(uint8_t mode)
+{
+    // Only DEFAULT is supported on the ESP8266
+    if (mode != DEFAULT) {
+        DEBUGV("analogReference called with illegal mode");
+    }
+}
+
+
+extern void analogReference(uint8_t mode) __attribute__ ((weak, alias("__analogReference")));
+
 };