From cbcefa7d3fe912d6d64634d57fb364e39a55c638 Mon Sep 17 00:00:00 2001 From: SarenT Date: Tue, 14 Aug 2018 03:53:39 +0200 Subject: [PATCH] Analog input voltage can be 3.3V (#5020) * Analog input voltage can be 3.3V According to this tutorial and my personal test with my Amica, 1.0V delivers 320 and 3.3V delivers 1024 at 10-bit resolution. I guess 3.3V is possible. * Update reference.rst Added warnings. * Update reference.rst * Update reference.rst requested changes --- doc/reference.rst | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/doc/reference.rst b/doc/reference.rst index fbff990f9..62c1d04ae 100644 --- a/doc/reference.rst +++ b/doc/reference.rst @@ -42,7 +42,12 @@ either to read voltage at ADC pin, or to read module supply voltage (VCC). To read external voltage applied to ADC pin, use ``analogRead(A0)``. -Input voltage range is 0 — 1.0V. +Input voltage range of bare ESP8266 is 0 — 1.0V, however some many +boards may implement voltage dividers. To be on the safe side, <1.0V +can be tested. If e.g. 0.5V delivers values around ~512, then maximum +voltage is very likely to be 1.0V and 3.3V may harm the ESP8266. +However values around ~150 indicates that the maximum voltage is +likely to be 3.3V. To read VCC voltage, use ``ESP.getVcc()`` and ADC pin must be kept unconnected. Additionally, the following line has to be added to the