diff --git a/Grbl_Esp32/config.h b/Grbl_Esp32/config.h
index d6be8eb6..b0057328 100644
--- a/Grbl_Esp32/config.h
+++ b/Grbl_Esp32/config.h
@@ -44,11 +44,11 @@ Some features should not be changed. See notes below.
 // The CPU map is the main definition of the machine/controller you want to use
 // These are typically found in the cpu_map.h file.
 // See Github repo wiki for more details
-#define CPU_MAP_TEST_DRIVE // these are defined in cpu_map.h
+#define CPU_MAP_ESP32 // these are defined in cpu_map.h
 
 // Number of axes defined (steppers, servos, etc) (valid range: 3 to 6)
-// Even if your machine only uses less than the minimum of 3, you should select 3 
-#define N_AXIS 3 
+// Even if your machine only uses less than the minimum of 3, you should select 3
+#define N_AXIS 3
 
 #define VERBOSE_HELP // Currently this doesn't do anything
 #define GRBL_MSG_LEVEL MSG_LEVEL_INFO // what level of [MSG:....] do you want to see 0=all off
@@ -288,7 +288,7 @@ Some features should not be changed. See notes below.
 #define IGNORE_CONTROL_PINS
 
 #define ENABLE_CONTROL_SW_DEBOUNCE // Default disabled. Uncomment to enable.
-#define CONTROL_SW_DEBOUNCE_PERIOD 32 // in milliseconds default 32 microseconds 
+#define CONTROL_SW_DEBOUNCE_PERIOD 32 // in milliseconds default 32 microseconds
 
 
 // Inverts select limit pin states based on the following mask. This effects all limit pin functions,
diff --git a/Grbl_Esp32/cpu_map.h b/Grbl_Esp32/cpu_map.h
index 3a188f60..7cc4fefe 100644
--- a/Grbl_Esp32/cpu_map.h
+++ b/Grbl_Esp32/cpu_map.h
@@ -585,19 +585,20 @@
 	#endif	
 		
 	#define USE_GANGED_AXES // allow two motors on an axis 
+	#define USE_RMT_STEPS
   
 	#define X_STEP_PIN      GPIO_NUM_12
-	#define X_STEP_B_PIN    GPIO_NUM_22	 // ganged motor
+	#define X2_STEP_PIN    GPIO_NUM_22	 // ganged motor
 	#define X_AXIS_SQUARING
 	
 	#define Y_STEP_PIN      GPIO_NUM_14
-	#define Y_STEP_B_PIN    GPIO_NUM_21  // ganged motor
+	#define Y2_STEP_PIN    GPIO_NUM_21  // ganged motor
 	#define Y_AXIS_SQUARING
 	
 	#define Z_STEP_PIN      GPIO_NUM_27
 	
 	#define X_DIRECTION_PIN   GPIO_NUM_26
-	#define Y_DIRECTION_PIN   GPIO_NUM_25  
+	#define Y_DIRECTION_PIN   GPIO_NUM_25
 	#define Z_DIRECTION_PIN   GPIO_NUM_33 
 	
 	// OK to comment out to use pin for other features
@@ -736,14 +737,14 @@
 	#define X_DIRECTION_PIN   GPIO_NUM_33 	// use Z labeled connector
 	
 	#define Y_STEP_PIN      GPIO_NUM_14
-	#define Y_STEP_B_PIN    GPIO_NUM_21  	// ganged motor
+	#define Y2_STEP_PIN    GPIO_NUM_21  	// ganged motor
 	#define Y_DIRECTION_PIN   GPIO_NUM_25 
 	#define Y_AXIS_SQUARING
 	
 	#define Z_STEP_PIN      GPIO_NUM_12  	// use X labeled connector
-	#define Z_STEP_B_PIN    GPIO_NUM_22		// use X labeled connector
+	#define Z2_STEP_PIN    GPIO_NUM_22		// use X labeled connector
 	#define Z_DIRECTION_PIN   GPIO_NUM_26 	// use X labeled connector
-	#define Z_AXIS_SQUARING	
+	#define Z_AXIS_SQUARING
 	
 	// OK to comment out to use pin for other features
 	#define STEPPERS_DISABLE_PIN GPIO_NUM_13
@@ -1082,6 +1083,52 @@
 	
 #endif
 
+#ifdef EXTERNAL_DRIVER_4X
+	#define CPU_MAP_NAME 		"External Driver Board V1.1"
+
+	#ifdef N_AXIS
+		#undef N_AXIS
+	#endif
+	#define N_AXIS 4
+
+	#define USE_RMT_STEPS	
+	#define X_STEP_PIN      	GPIO_NUM_0
+	#define X_DIRECTION_PIN   	GPIO_NUM_2
+	#define Y_STEP_PIN      	GPIO_NUM_26
+	#define Y_DIRECTION_PIN   	GPIO_NUM_15
+	#define Z_STEP_PIN      	GPIO_NUM_27
+	#define Z_DIRECTION_PIN   	GPIO_NUM_33
+	#define A_STEP_PIN      	GPIO_NUM_14
+	#define A_DIRECTION_PIN   	GPIO_NUM_12
+	#define STEPPERS_DISABLE_PIN GPIO_NUM_13
+
+	
+	#define SPINDLE_PWM_PIN    	GPIO_NUM_25
+	#define SPINDLE_PWM_CHANNEL 0
+	#define SPINDLE_PWM_BIT_PRECISION 8
+	#define SPINDLE_ENABLE_PIN	GPIO_NUM_22
+	
+	#define MODBUS_TX	GPIO_NUM_17
+	#define MODBUS_RX	GPIO_NUM_4
+	#define MODBUS_CTRL	GPIO_NUM_16
+	
+	#define X_LIMIT_PIN      	GPIO_NUM_34	
+	#define Y_LIMIT_PIN      	GPIO_NUM_35	
+	#define Z_LIMIT_PIN      	GPIO_NUM_36
+
+	#if (N_AXIS == 3)
+		#define LIMIT_MASK      	B0111
+	#else
+		#define A_LIMIT_PIN      	GPIO_NUM_39
+		#define LIMIT_MASK      	B1111
+	#endif
+
+	#define PROBE_PIN       	GPIO_NUM_32
+	#define COOLANT_MIST_PIN   	GPIO_NUM_21
+
+	
+#endif
+
 #ifdef CPU_MAP_ATARI_1020
 	#include "atari_1020.h"	
 #endif
diff --git a/Grbl_Esp32/grbl.h b/Grbl_Esp32/grbl.h
index 1d23575c..519f469f 100644
--- a/Grbl_Esp32/grbl.h
+++ b/Grbl_Esp32/grbl.h
@@ -20,7 +20,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "1.1f"
-#define GRBL_VERSION_BUILD "20200219"
+#define GRBL_VERSION_BUILD "20200221"
 
 //#include <sdkconfig.h>
 #include <Arduino.h>
diff --git a/Grbl_Esp32/stepper.cpp b/Grbl_Esp32/stepper.cpp
index 9c4ba830..29a1f718 100644
--- a/Grbl_Esp32/stepper.cpp
+++ b/Grbl_Esp32/stepper.cpp
@@ -152,6 +152,21 @@ typedef struct {
 } st_prep_t;
 static st_prep_t prep;
 
+// RMT channel numbers. These are assigned dynamically as needed via the CPU MAP
+// Only 8 are available (0-7) 
+// They are Initialized with an invalid number to prevent unitended consequences
+uint8_t X_rmt_chan_num = 255;
+uint8_t X2_rmt_chan_num = 255; // Ganged axes have the "2"
+uint8_t Y_rmt_chan_num = 255;
+uint8_t Y2_rmt_chan_num = 255;
+uint8_t Z_rmt_chan_num = 255;
+uint8_t Z2_rmt_chan_num = 255;
+uint8_t A_rmt_chan_num = 255;
+uint8_t A2_rmt_chan_num = 255;
+uint8_t B_rmt_chan_num = 255;
+uint8_t B2_rmt_chan_num = 255;
+uint8_t C_rmt_chan_num = 255;
+uint8_t C2_rmt_chan_num = 255;
 
 /* "The Stepper Driver Interrupt" - This timer interrupt is the workhorse of Grbl. Grbl employs
    the venerable Bresenham line algorithm to manage and exactly synchronize multi-axis moves.
@@ -458,22 +473,22 @@ void stepper_init()
 		#ifdef  X_STEP_PIN
 			pinMode(X_STEP_PIN, OUTPUT);
 		#endif
-		#ifdef  X_STEP_B_PIN // ganged motor
-			pinMode(X_STEP_B_PIN, OUTPUT);
+		#ifdef  X2_STEP_PIN // ganged motor
+			pinMode(X2_STEP_PIN, OUTPUT);
 		#endif
 
 		#ifdef Y_STEP_PIN
 			pinMode(Y_STEP_PIN, OUTPUT);
 		#endif
-		#ifdef Y_STEP_B_PIN
-			pinMode(Y_STEP_B_PIN, OUTPUT);
+		#ifdef Y2_STEP_PIN
+			pinMode(Y2_STEP_PIN, OUTPUT);
 		#endif
 
 		#ifdef Z_STEP_PIN
 			pinMode(Z_STEP_PIN, OUTPUT);
 		#endif
-		#ifdef Z_STEP_B_PIN
-			pinMode(Z_STEP_B_PIN, OUTPUT);
+		#ifdef Z2_STEP_PIN
+			pinMode(Z2_STEP_PIN, OUTPUT);
 		#endif
 		
 		#ifdef A_STEP_PIN
@@ -536,8 +551,6 @@ void stepper_init()
 	timer_set_counter_value(STEP_TIMER_GROUP, STEP_TIMER_INDEX, 0x00000000ULL);
 	timer_enable_intr(STEP_TIMER_GROUP, STEP_TIMER_INDEX);
 	timer_isr_register(STEP_TIMER_GROUP, STEP_TIMER_INDEX, onStepperDriverTimer, NULL, 0, NULL);
-
-
 }
 
 #ifdef USE_RMT_STEPS
@@ -567,8 +580,9 @@ void initRMT()
 	rmtItem[1].duration1 = 0;
 
 #ifdef X_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)X_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)X_RMT_CHANNEL;
+	X_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)X_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)X_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, X_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = X_STEP_PIN;
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -577,11 +591,12 @@ void initRMT()
 	rmt_fill_tx_items(rmtConfig.channel, &rmtItem[0], rmtConfig.mem_block_num, 0);
 #endif
 
-#ifdef X_STEP_B_PIN
-	rmt_set_source_clk( (rmt_channel_t)X_B_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)X_B_RMT_CHANNEL;
+#ifdef X2_STEP_PIN
+	X2_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)X2_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)X2_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, X_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
-	rmtConfig.gpio_num = X_STEP_B_PIN;
+	rmtConfig.gpio_num = X2_STEP_PIN;
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
 	rmtItem[0].level1 = !rmtConfig.tx_config.idle_level;
 	rmt_config(&rmtConfig);
@@ -589,8 +604,9 @@ void initRMT()
 #endif
 
 #ifdef Y_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)Y_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)Y_RMT_CHANNEL;
+	Y_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)Y_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)Y_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, Y_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = Y_STEP_PIN;
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -599,11 +615,12 @@ void initRMT()
 	rmt_fill_tx_items(rmtConfig.channel, &rmtItem[0], rmtConfig.mem_block_num, 0);
 #endif
 
-#ifdef Y_STEP_B_PIN
-	rmt_set_source_clk( (rmt_channel_t)Y_B_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)Y_B_RMT_CHANNEL;
+#ifdef Y2_STEP_PIN
+	Y2_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)Y2_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)Y2_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, Y_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
-	rmtConfig.gpio_num = Y_STEP_B_PIN;
+	rmtConfig.gpio_num = Y2_STEP_PIN;
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
 	rmtItem[0].level1 = !rmtConfig.tx_config.idle_level;
 	rmt_config(&rmtConfig);
@@ -611,8 +628,9 @@ void initRMT()
 #endif
 
 #ifdef Z_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)Z_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)Z_RMT_CHANNEL;
+	Z_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)Z_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)Z_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, Z_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = Z_STEP_PIN;
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -622,8 +640,9 @@ void initRMT()
 #endif
 
 #ifdef A_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)A_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)A_RMT_CHANNEL;
+	A_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)A_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)A_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, A_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = A_STEP_PIN;  // TODO
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -633,8 +652,9 @@ void initRMT()
 #endif
 
 #ifdef B_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)B_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)B_RMT_CHANNEL;
+	B_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)B_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)B_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, B_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = B_STEP_PIN;  // TODO
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -644,8 +664,9 @@ void initRMT()
 #endif
 
 #ifdef C_STEP_PIN
-	rmt_set_source_clk( (rmt_channel_t)C_RMT_CHANNEL, RMT_BASECLK_APB);
-	rmtConfig.channel = (rmt_channel_t)C_RMT_CHANNEL;
+	C_rmt_chan_num = sys_get_next_RMT_chan_num();
+	rmt_set_source_clk( (rmt_channel_t)C_rmt_chan_num, RMT_BASECLK_APB);
+	rmtConfig.channel = (rmt_channel_t)C_rmt_chan_num;
 	rmtConfig.tx_config.idle_level = bit_istrue(settings.step_invert_mask, C_AXIS) ? RMT_IDLE_LEVEL_HIGH : RMT_IDLE_LEVEL_LOW;
 	rmtConfig.gpio_num = C_STEP_PIN;  // TODO
 	rmtItem[0].level0 = rmtConfig.tx_config.idle_level;
@@ -725,97 +746,117 @@ void set_direction_pins_on(uint8_t onMask)
 #ifdef X_DIRECTION_PIN
 	digitalWrite(X_DIRECTION_PIN, (onMask & (1<<X_AXIS)));
 #endif
+#ifdef X2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(X2_DIRECTION_PIN, (onMask & (1<<X_AXIS)));
+#endif
+
 #ifdef Y_DIRECTION_PIN
 	digitalWrite(Y_DIRECTION_PIN, (onMask & (1<<Y_AXIS)));
 #endif
+#ifdef Y2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(Y2_DIRECTION_PIN, (onMask & (1<<Y_AXIS)));
+#endif
+
 #ifdef Z_DIRECTION_PIN
 	digitalWrite(Z_DIRECTION_PIN, (onMask & (1<<Z_AXIS)));
 #endif
+#ifdef Z2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(Z2_DIRECTION_PIN, (onMask & (1<<Z_AXIS)));
+#endif
+
 #ifdef A_DIRECTION_PIN
 	digitalWrite(A_DIRECTION_PIN, (onMask & (1<<A_AXIS)));
 #endif
+#ifdef A2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(A2_DIRECTION_PIN, (onMask & (1<<A_AXIS)));
+#endif
+
 #ifdef B_DIRECTION_PIN
 	digitalWrite(B_DIRECTION_PIN, (onMask & (1<<B_AXIS)));
 #endif
+#ifdef B2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(B2_DIRECTION_PIN, (onMask & (1<<B_AXIS)));
+#endif
+
 #ifdef C_DIRECTION_PIN
 	digitalWrite(C_DIRECTION_PIN, (onMask & (1<<C_AXIS)));
 #endif
-
+#ifdef C2_DIRECTION_PIN // optional ganged axis 
+	digitalWrite(C2_DIRECTION_PIN, (onMask & (1<<C_AXIS)));
+#endif
 
 }
 
 #ifndef USE_GANGED_AXES
 // basic one motor per axis
-void set_stepper_pins_on(uint8_t onMask)
-{
-	onMask ^= settings.step_invert_mask; // invert pins as required by invert mask
+	void set_stepper_pins_on(uint8_t onMask)
+	{
+		onMask ^= settings.step_invert_mask; // invert pins as required by invert mask
 
-#ifdef X_STEP_PIN
-	digitalWrite(X_STEP_PIN, (onMask & (1<<X_AXIS)));
-#endif
-
-#ifdef Y_STEP_PIN
-	digitalWrite(Y_STEP_PIN, (onMask & (1<<Y_AXIS)));
-#endif
-
-#ifdef Z_STEP_PIN
-	digitalWrite(Z_STEP_PIN, (onMask & (1<<Z_AXIS)));
-#endif
-
-#ifdef A_STEP_PIN
-	digitalWrite(A_STEP_PIN, (onMask & (1<<A_AXIS)));
-#endif
-}
-#else // we use ganged axes
-void set_stepper_pins_on(uint8_t onMask)
-{
-	onMask ^= settings.step_invert_mask; // invert pins as required by invert mask
-
-#ifdef X_STEP_PIN
-#ifndef X_STEP_B_PIN // if not a ganged axis
-	digitalWrite(X_STEP_PIN, (onMask & (1<<X_AXIS)));
-#else // is a ganged axis
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+	#ifdef X_STEP_PIN
 		digitalWrite(X_STEP_PIN, (onMask & (1<<X_AXIS)));
-	}
+	#endif
 
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
-		digitalWrite(X_STEP_B_PIN, (onMask & (1<<X_AXIS)));
-	}
-#endif
-#endif
-
-#ifdef Y_STEP_PIN
-#ifndef Y_STEP_B_PIN // if not a ganged axis
-	digitalWrite(Y_STEP_PIN, (onMask & (1<<Y_AXIS)));
-#else // is a ganged axis
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+	#ifdef Y_STEP_PIN
 		digitalWrite(Y_STEP_PIN, (onMask & (1<<Y_AXIS)));
-	}
+	#endif
 
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
-		digitalWrite(Y_STEP_B_PIN, (onMask & (1<<Y_AXIS)));
-	}
-#endif
-#endif
-
-#ifdef Z_STEP_PIN
-#ifndef Z_STEP_B_PIN // if not a ganged axis
-	digitalWrite(Z_STEP_PIN, (onMask & (1<<Z_AXIS)));
-#else // is a ganged axis
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+	#ifdef Z_STEP_PIN
 		digitalWrite(Z_STEP_PIN, (onMask & (1<<Z_AXIS)));
+	#endif
+
+	#ifdef A_STEP_PIN
+		digitalWrite(A_STEP_PIN, (onMask & (1<<A_AXIS)));
+	#endif
 	}
+#else // we use ganged axes
+	void set_stepper_pins_on(uint8_t onMask)
+	{
+		onMask ^= settings.step_invert_mask; // invert pins as required by invert mask
 
-	if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
-		digitalWrite(Z_STEP_B_PIN, (onMask & (1<<Z_AXIS)));
+		#ifdef X_STEP_PIN
+			#ifndef X2_STEP_PIN // if not a ganged axis
+				digitalWrite(X_STEP_PIN, (onMask & (1<<X_AXIS)));
+			#else // is a ganged axis
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+					digitalWrite(X_STEP_PIN, (onMask & (1<<X_AXIS)));
+				}
+
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
+					digitalWrite(X2_STEP_PIN, (onMask & (1<<X_AXIS)));
+				}
+			#endif
+		#endif
+
+		#ifdef Y_STEP_PIN
+			#ifndef Y2_STEP_PIN // if not a ganged axis
+				digitalWrite(Y_STEP_PIN, (onMask & (1<<Y_AXIS)));
+			#else // is a ganged axis
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+					digitalWrite(Y_STEP_PIN, (onMask & (1<<Y_AXIS)));
+				}
+
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
+					digitalWrite(Y2_STEP_PIN, (onMask & (1<<Y_AXIS)));
+				}
+			#endif
+		#endif
+
+		#ifdef Z_STEP_PIN
+			#ifndef Z2_STEP_PIN // if not a ganged axis
+				digitalWrite(Z_STEP_PIN, (onMask & (1<<Z_AXIS)));
+			#else // is a ganged axis
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
+					digitalWrite(Z_STEP_PIN, (onMask & (1<<Z_AXIS)));
+				}
+
+				if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
+					digitalWrite(Z2_STEP_PIN, (onMask & (1<<Z_AXIS)));
+				}
+			#endif
+		#endif
 	}
 #endif
-#endif
-
-
-}
-#endif
 
 #ifdef USE_RMT_STEPS
 // Set stepper pulse output pins
@@ -824,17 +865,17 @@ inline IRAM_ATTR static void stepperRMT_Outputs()
 	
 #ifdef  X_STEP_PIN
 	if(st.step_outbits & (1<<X_AXIS)) {
-	#ifndef X_STEP_B_PIN // if not a ganged axis
-			RMT.conf_ch[X_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-			RMT.conf_ch[X_RMT_CHANNEL].conf1.tx_start = 1;
+	#ifndef X2_STEP_PIN // if not a ganged axis
+			RMT.conf_ch[X_rmt_chan_num].conf1.mem_rd_rst = 1;
+			RMT.conf_ch[X_rmt_chan_num].conf1.tx_start = 1;
 	#else // it is a ganged axis
 			if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
-				RMT.conf_ch[X_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-				RMT.conf_ch[X_RMT_CHANNEL].conf1.tx_start = 1;			}
+				RMT.conf_ch[X_rmt_chan_num].conf1.mem_rd_rst = 1;
+				RMT.conf_ch[X_rmt_chan_num].conf1.tx_start = 1;			}
 			
 			if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
-				RMT.conf_ch[X_B_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-				RMT.conf_ch[X_B_RMT_CHANNEL].conf1.tx_start = 1;
+				RMT.conf_ch[X2_rmt_chan_num].conf1.mem_rd_rst = 1;
+				RMT.conf_ch[X2_rmt_chan_num].conf1.tx_start = 1;
 			}			
 	#endif
 	}
@@ -843,17 +884,17 @@ inline IRAM_ATTR static void stepperRMT_Outputs()
 
 #ifdef  Y_STEP_PIN
 	if(st.step_outbits & (1<<Y_AXIS)) {
-#ifndef Y_STEP_B_PIN // if not a ganged axis
-		RMT.conf_ch[Y_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-		RMT.conf_ch[Y_RMT_CHANNEL].conf1.tx_start = 1;
+#ifndef Y2_STEP_PIN // if not a ganged axis
+		RMT.conf_ch[Y_rmt_chan_num].conf1.mem_rd_rst = 1;
+		RMT.conf_ch[Y_rmt_chan_num].conf1.tx_start = 1;
 #else // it is a ganged axis
 		if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_A) ) {
-			RMT.conf_ch[Y_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-			RMT.conf_ch[Y_RMT_CHANNEL].conf1.tx_start = 1;
+			RMT.conf_ch[Y_rmt_chan_num].conf1.mem_rd_rst = 1;
+			RMT.conf_ch[Y_rmt_chan_num].conf1.tx_start = 1;
 		}		
 		if ( (ganged_mode == SQUARING_MODE_DUAL) || (ganged_mode == SQUARING_MODE_B) ) {
-			RMT.conf_ch[Y_B_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-			RMT.conf_ch[Y_B_RMT_CHANNEL].conf1.tx_start = 1;
+			RMT.conf_ch[Y2_rmt_chan_num].conf1.mem_rd_rst = 1;
+			RMT.conf_ch[Y2_rmt_chan_num].conf1.tx_start = 1;
 		}		
 #endif
 	}
@@ -861,32 +902,32 @@ inline IRAM_ATTR static void stepperRMT_Outputs()
 
 #ifdef  Z_STEP_PIN
 	if(st.step_outbits & (1<<Z_AXIS)) {
-		RMT.conf_ch[Z_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-		RMT.conf_ch[Z_RMT_CHANNEL].conf1.tx_start = 1;
+		RMT.conf_ch[Z_rmt_chan_num].conf1.mem_rd_rst = 1;
+		RMT.conf_ch[Z_rmt_chan_num].conf1.tx_start = 1;
 	}
 #endif
 
 #ifdef  A_STEP_PIN
 	if(st.step_outbits & (1<<A_AXIS)) {
 		
-		RMT.conf_ch[A_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-		RMT.conf_ch[A_RMT_CHANNEL].conf1.tx_start = 1;
+		RMT.conf_ch[A_rmt_chan_num].conf1.mem_rd_rst = 1;
+		RMT.conf_ch[A_rmt_chan_num].conf1.tx_start = 1;
 	}
 #endif
 
 #ifdef  B_STEP_PIN
 	if(st.step_outbits & (1<<B_AXIS)) {
 		
-		RMT.conf_ch[B_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-		RMT.conf_ch[B_RMT_CHANNEL].conf1.tx_start = 1;
+		RMT.conf_ch[B_rmt_chan_num].conf1.mem_rd_rst = 1;
+		RMT.conf_ch[B_rmt_chan_num].conf1.tx_start = 1;
 	}
 #endif
 
 #ifdef  C_STEP_PIN
 	if(st.step_outbits & (1<<C_AXIS)) {
 		
-		RMT.conf_ch[C_RMT_CHANNEL].conf1.mem_rd_rst = 1;
-		RMT.conf_ch[C_RMT_CHANNEL].conf1.tx_start = 1;
+		RMT.conf_ch[C_rmt_chan_num].conf1.mem_rd_rst = 1;
+		RMT.conf_ch[C_rmt_chan_num].conf1.tx_start = 1;
 	}
 #endif
 
@@ -1535,7 +1576,4 @@ bool get_stepper_disable()   // returns true if steppers are disabled
 
 	return disabled;
 
-}
-
-
-
+}
\ No newline at end of file
diff --git a/Grbl_Esp32/stepper.h b/Grbl_Esp32/stepper.h
index d99a9d01..d2dd6bbd 100644
--- a/Grbl_Esp32/stepper.h
+++ b/Grbl_Esp32/stepper.h
@@ -47,14 +47,6 @@
 #define PREP_FLAG_PARKING bit(2)
 #define PREP_FLAG_DECEL_OVERRIDE bit(3)
 
-// which RMT channels to use with the axes
-#define X_RMT_CHANNEL		0
-#define Y_RMT_CHANNEL		1
-#define Z_RMT_CHANNEL		2
-#define A_RMT_CHANNEL		3
-#define B_RMT_CHANNEL		4
-#define C_RMT_CHANNEL		5
-
 // Define Adaptive Multi-Axis Step-Smoothing(AMASS) levels and cutoff frequencies. The highest level
 // frequency bin starts at 0Hz and ends at its cutoff frequency. The next lower level frequency bin
 // starts at the next higher cutoff frequency, and so on. The cutoff frequencies for each level must
diff --git a/Grbl_Esp32/system.cpp b/Grbl_Esp32/system.cpp
index d17e5a37..f1605658 100644
--- a/Grbl_Esp32/system.cpp
+++ b/Grbl_Esp32/system.cpp
@@ -623,4 +623,19 @@ void sys_io_control(uint8_t io_num_mask, bool turnOn) {
 			return;
 		}
 	#endif
+}
+
+// Call this function to get an RMT channel number
+// returns -1 for error
+int8_t sys_get_next_RMT_chan_num()
+{
+  static uint8_t next_RMT_chan_num = 0; // channels 0-7 are valid
+
+  if (next_RMT_chan_num< 8) { // 7 is the max PWM channel number
+    return next_RMT_chan_num++;
+  }
+  else {
+    grbl_msg_sendf(CLIENT_SERIAL, MSG_LEVEL_ERROR, "Error: out of RMT channels");
+    return -1;
+  }
 }
\ No newline at end of file
diff --git a/Grbl_Esp32/system.h b/Grbl_Esp32/system.h
index 787a82c8..8a6ae5fd 100644
--- a/Grbl_Esp32/system.h
+++ b/Grbl_Esp32/system.h
@@ -227,5 +227,7 @@ void system_exec_control_pin(uint8_t pin);
 
 void sys_io_control(uint8_t io_num_mask, bool turnOn);
 
+// 
+int8_t sys_get_next_RMT_chan_num();
 
 #endif