From 31059a615c20bfb1814685ea0e9b9f09383c8fe3 Mon Sep 17 00:00:00 2001
From: Harald Barth <haba@kth.se>
Date: Wed, 27 Oct 2021 23:03:37 +0200
Subject: [PATCH] use ESP-IDF ADC functions instead of analogRead() which
 breaks waveform

---
 MotorDriver.cpp  | 12 ++++++++++++
 config.example.h | 15 ++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/MotorDriver.cpp b/MotorDriver.cpp
index 8bcb03c..8959f42 100644
--- a/MotorDriver.cpp
+++ b/MotorDriver.cpp
@@ -20,6 +20,10 @@
 #include "MotorDriver.h"
 #include "DCCTimer.h"
 #include "DIAG.h"
+#if defined(ARDUINO_ARCH_ESP32)
+#include <driver/adc.h>
+#define pinToADC1Channel(X) (adc1_channel_t)(((X) > 35) ? (X)-36 : (X)-28)
+#endif
 
 bool MotorDriver::usePWM=false;
 bool MotorDriver::commonFaultPin=false;
@@ -55,7 +59,13 @@ MotorDriver::MotorDriver(byte power_pin, byte signal_pin, byte signal_pin2, int8
   currentPin=current_pin;
   if (currentPin!=UNUSED_PIN) {
     pinMode(currentPin, INPUT);
+#if defined(ARDUINO_ARCH_ESP32)
+    adc1_config_width(ADC_WIDTH_BIT_12);
+    adc1_config_channel_atten(pinToADC1Channel(currentPin),ADC_ATTEN_DB_11);
+    senseOffset = adc1_get_raw(pinToADC1Channel(currentPin));
+#else
     senseOffset=analogRead(currentPin); // value of sensor at zero current
+#endif
   }
 
   faultPin=fault_pin;
@@ -150,6 +160,8 @@ int MotorDriver::getCurrentRaw() {
   current = analogRead(currentPin)-senseOffset;
   overflow_count = 0;
   SREG = sreg_backup;    /* restore interrupt state */
+#elif defined(ARDUINO_ARCH_ESP32)
+  current = adc1_get_raw(pinToADC1Channel(currentPin))-senseOffset;
 #else
   current = analogRead(currentPin)-senseOffset;
 #endif
diff --git a/config.example.h b/config.example.h
index 7338051..2d345e2 100644
--- a/config.example.h
+++ b/config.example.h
@@ -43,19 +43,24 @@ The configuration file for DCC-EX Command Station
 //
 //#define MOTOR_SHIELD_TYPE STANDARD_MOTOR_SHIELD
 
+// https://randomnerdtutorials.com/esp8266-pinout-reference-gpios/
+// 4 high at boot
 #define ESP8266_MOTOR_SHIELD F("ESP8266"),					\
  new MotorDriver(D3, D5, UNUSED_PIN, UNUSED_PIN, UNUSED_PIN, 2.99, 2000, UNUSED_PIN),\
  new MotorDriver(D2, D6, UNUSED_PIN, UNUSED_PIN, A0        , 2.99, 2000, UNUSED_PIN)
 
-// ADC1 CH4 = GPIO32
-// ADC1 CH5 = GPIO33
+// ESP32 ADC1 only supported GPIO pins 32 to 39, for example
+// ADC1 CH4 = GPIO32, ADC1 CH5 = GPIO33, ADC1 CH0 = GPIO36
+//
 // Adjust pin usage according to info in
 // https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/
 // https://randomnerdtutorials.com/esp32-pinout-reference-gpios/
-// Adjust conversion factor according to your voltage divider
+//
+// Adjust conversion factor according to your voltage divider.
+//
 #define ESP32_MOTOR_SHIELD F("ESP32"), \
- new MotorDriver(16, 17, UNUSED_PIN, UNUSED_PIN, 32, 2.99, 2000, UNUSED_PIN),\
- new MotorDriver(18, 19, UNUSED_PIN, UNUSED_PIN, 33, 2.99, 2000, UNUSED_PIN)
+ new MotorDriver(16, 17, UNUSED_PIN, UNUSED_PIN, 32, 2.00, 2000, UNUSED_PIN),\
+ new MotorDriver(18, 19, UNUSED_PIN, UNUSED_PIN, 33, 2.00, 2000, UNUSED_PIN)
 
 #define MOTOR_SHIELD_TYPE ESP32_MOTOR_SHIELD