From 72d02d0474f97105187895cde4f627d18fb7b6ce Mon Sep 17 00:00:00 2001
From: Scott Lahteine <thinkyhead@users.noreply.github.com>
Date: Mon, 30 Aug 2021 22:14:26 -0500
Subject: [PATCH] Revert #22618 until solved

---
 Marlin/src/libs/MAX31865.cpp | 31 ++++++++++++++++++++-----------
 Marlin/src/libs/MAX31865.h   |  1 -
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/Marlin/src/libs/MAX31865.cpp b/Marlin/src/libs/MAX31865.cpp
index 8a96e661a79cd..1264c6fbe88ec 100644
--- a/Marlin/src/libs/MAX31865.cpp
+++ b/Marlin/src/libs/MAX31865.cpp
@@ -48,7 +48,7 @@
 
 #if HAS_MAX31865 && !USE_ADAFRUIT_MAX31865
 
-#include <SoftwareSPI.h>
+//#include <SoftwareSPI.h> // TODO: switch to SPIclass/SoftSPI
 #include "MAX31865.h"
 
 // The maximum speed the MAX31865 can do is 5 MHz
@@ -61,7 +61,7 @@ SPISettings MAX31865::spiConfig = SPISettings(
     500000
   #endif
   , MSBFIRST
-  , SPI_MODE1 // CPOL0 CPHA1
+  , SPI_MODE_1 // CPOL0 CPHA1
 );
 
 #ifndef LARGE_PINMAP
@@ -152,15 +152,17 @@ void MAX31865::begin(max31865_numwires_t wires, float zero, float ref) {
   OUT_WRITE(_cs, HIGH);
 
   if (_sclk != TERN(LARGE_PINMAP, -1UL, -1)) {
-    // define pin modes for Software SPI
+    // Define pin modes for Software SPI
     #ifdef MAX31865_DEBUG
       SERIAL_ECHOLN("Initializing MAX31865 Software SPI");
     #endif
 
-    swSpiBegin(_sclk, _miso, _mosi);
-
-  } else {
-    // start and configure hardware SPI
+    OUT_WRITE(_sclk, LOW);
+    SET_OUTPUT(_mosi);
+    SET_INPUT(_miso);
+  }
+  else {
+    // Start and configure hardware SPI
     #ifdef MAX31865_DEBUG
       SERIAL_ECHOLN("Initializing MAX31865 Hardware SPI");
     #endif
@@ -168,9 +170,6 @@ void MAX31865::begin(max31865_numwires_t wires, float zero, float ref) {
     SPI.begin();
   }
 
-  // SPI Begin must be called first, then init
-  _spi_speed = swSpiInit(SPI_QUARTER_SPEED, _sclk, _mosi);
-
   setWires(wires);
   enableBias(false);
   autoConvert(false);
@@ -485,7 +484,17 @@ uint8_t MAX31865::spixfer(uint8_t x) {
   if (_sclk == TERN(LARGE_PINMAP, -1UL, -1))
     return SPI.transfer(x);
 
-  return swSpiTransfer(x, _spi_speed, _sclk, _miso, _mosi);
+  uint8_t reply = 0;
+  for (int i = 7; i >= 0; i--) {
+    reply <<= 1;
+    WRITE(_sclk, HIGH);
+    WRITE(_mosi, x & (1 << i));
+    WRITE(_sclk, LOW);
+    if (READ(_miso))
+      reply |= 1;
+  }
+
+  return reply;
 }
 
 #endif // HAS_MAX31865 && !USE_ADAFRUIT_MAX31865
diff --git a/Marlin/src/libs/MAX31865.h b/Marlin/src/libs/MAX31865.h
index 13a117447dcab..5d50e870ecd2a 100644
--- a/Marlin/src/libs/MAX31865.h
+++ b/Marlin/src/libs/MAX31865.h
@@ -90,7 +90,6 @@ class MAX31865 {
   static SPISettings spiConfig;
 
   TERN(LARGE_PINMAP, uint32_t, uint8_t) _sclk, _miso, _mosi, _cs;
-  uint8_t _spi_speed;
   float Rzero, Rref;
 
   void setConfig(uint8_t config, bool enable);