From f812394c33b0484f4bd24ef101c3c9250a74ab24 Mon Sep 17 00:00:00 2001 From: Nicko van Someren Date: Thu, 9 May 2019 13:57:45 -0600 Subject: [PATCH] docs/esp32: Correct quickref for ESP32 hardware SPI with non-default IO. --- docs/esp32/quickref.rst | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/docs/esp32/quickref.rst b/docs/esp32/quickref.rst index 5ac8aa3b2f..76fe0d9f9e 100644 --- a/docs/esp32/quickref.rst +++ b/docs/esp32/quickref.rst @@ -128,6 +128,8 @@ with timer ID of -1:: The period is in milliseconds. +.. _Pins_and_GPIO: + Pins and GPIO ------------- @@ -274,8 +276,13 @@ class:: Hardware SPI bus ---------------- -There are two hardware SPI channels that allow faster (up to 80Mhz) -transmission rates, but are only supported on a subset of pins. +There are two hardware SPI channels that allow faster transmission +rates (up to 80Mhz). These may be used on any IO pins that support the +required direction and are otherwise unused (see :ref:`Pins_and_GPIO`) +but if they are not configured to their default pins then they need to +pass through an extra layer of GPIO multiplexing, which can impact +their reliability at high speeds. Hardware SPI channels are limited +to 40MHz when used on pins other than the default ones listed below. ===== =========== ============ \ HSPI (id=1) VSPI (id=2)