diff --git a/.idea/cmake.xml b/.idea/cmake.xml
index 311c3ccb9..97e503033 100644
--- a/.idea/cmake.xml
+++ b/.idea/cmake.xml
@@ -40,7 +40,9 @@
         </ADDITIONAL_GENERATION_ENVIRONMENT>
       </configuration>
       <configuration PROFILE_NAME="metro_m0_express" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=metro_m0_express -DLOG=3 -DLOGGER=RTT -DMAX3421_HOST=1" />
+      <configuration PROFILE_NAME="feather_m0_express" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=feather_m0_express -DLOG=3 -DLOGGER=RTT -DMAX3421_HOST=1" />
       <configuration PROFILE_NAME="metro_m4_express" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=metro_m4_express -DLOG=3 -DLOGGER=RTT -DMAX3421_HOST=1" />
+      <configuration PROFILE_NAME="feather_m4_express" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=feather_m4_express -DLOG=3 -DLOGGER=RTT -DMAX3421_HOST=1" />
       <configuration PROFILE_NAME="feather_nrf52840_express" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=feather_nrf52840_express -DLOG=3 -DLOGGER=RTT -DMAX3421_HOST=1" />
       <configuration PROFILE_NAME="pca10056" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=pca10056 -DLOG=3 -DLOGGER=RTT -DTRACE_ETM=1" />
       <configuration PROFILE_NAME="pca10095" ENABLED="false" CONFIG_NAME="Debug" GENERATION_OPTIONS="-DBOARD=pca10095 -DLOG=3 -DLOGGER=RTT -DTRACE_ETM=1" />
diff --git a/examples/host/cdc_msc_hid/src/main.c b/examples/host/cdc_msc_hid/src/main.c
index 405bf8c06..a3b80e030 100644
--- a/examples/host/cdc_msc_hid/src/main.c
+++ b/examples/host/cdc_msc_hid/src/main.c
@@ -34,13 +34,17 @@
 // MACRO CONSTANT TYPEDEF PROTYPES
 //--------------------------------------------------------------------+
 void led_blinking_task(void);
-
 extern void cdc_app_task(void);
 extern void hid_app_task(void);
 
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
+// API to read/rite MAX3421's register. Implemented by TinyUSB
+extern uint8_t tuh_max3421_reg_read(uint8_t rhport, uint8_t reg, bool in_isr);
+extern bool tuh_max3421_reg_write(uint8_t rhport, uint8_t reg, uint8_t data, bool in_isr);
+#endif
+
 /*------------- MAIN -------------*/
-int main(void)
-{
+int main(void) {
   board_init();
 
   printf("TinyUSB Host CDC MSC HID Example\r\n");
@@ -52,8 +56,13 @@ int main(void)
     board_init_after_tusb();
   }
 
-  while (1)
-  {
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
+  // FeatherWing MAX3421E use MAX3421E's GPIO0 for VBUS enable
+  enum { IOPINS1_ADDR  = 20u << 3, /* 0xA0 */ };
+  tuh_max3421_reg_write(BOARD_TUH_RHPORT, IOPINS1_ADDR, 0x01, false);
+#endif
+
+  while (1) {
     // tinyusb host task
     tuh_task();
 
@@ -67,14 +76,12 @@ int main(void)
 // TinyUSB Callbacks
 //--------------------------------------------------------------------+
 
-void tuh_mount_cb(uint8_t dev_addr)
-{
+void tuh_mount_cb(uint8_t dev_addr) {
   // application set-up
   printf("A device with address %d is mounted\r\n", dev_addr);
 }
 
-void tuh_umount_cb(uint8_t dev_addr)
-{
+void tuh_umount_cb(uint8_t dev_addr) {
   // application tear-down
   printf("A device with address %d is unmounted \r\n", dev_addr);
 }
@@ -83,15 +90,14 @@ void tuh_umount_cb(uint8_t dev_addr)
 //--------------------------------------------------------------------+
 // Blinking Task
 //--------------------------------------------------------------------+
-void led_blinking_task(void)
-{
+void led_blinking_task(void) {
   const uint32_t interval_ms = 1000;
   static uint32_t start_ms = 0;
 
   static bool led_state = false;
 
   // Blink every interval ms
-  if ( board_millis() - start_ms < interval_ms) return; // not enough time
+  if (board_millis() - start_ms < interval_ms) return; // not enough time
   start_ms += interval_ms;
 
   board_led_write(led_state);
diff --git a/examples/host/cdc_msc_hid_freertos/src/main.c b/examples/host/cdc_msc_hid_freertos/src/main.c
index 691ff3e29..069cbdc90 100644
--- a/examples/host/cdc_msc_hid_freertos/src/main.c
+++ b/examples/host/cdc_msc_hid_freertos/src/main.c
@@ -83,6 +83,12 @@ extern void cdc_app_init(void);
 extern void hid_app_init(void);
 extern void msc_app_init(void);
 
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
+// API to read/rite MAX3421's register. Implemented by TinyUSB
+extern uint8_t tuh_max3421_reg_read(uint8_t rhport, uint8_t reg, bool in_isr);
+extern bool tuh_max3421_reg_write(uint8_t rhport, uint8_t reg, uint8_t data, bool in_isr);
+#endif
+
 /*------------- MAIN -------------*/
 int main(void) {
   board_init();
@@ -126,6 +132,12 @@ static void usb_host_task(void *param) {
     board_init_after_tusb();
   }
 
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
+  // FeatherWing MAX3421E use MAX3421E's GPIO0 for VBUS enable
+  enum { IOPINS1_ADDR  = 20u << 3, /* 0xA0 */ };
+  tuh_max3421_reg_write(BOARD_TUH_RHPORT, IOPINS1_ADDR, 0x01, false);
+#endif
+
   cdc_app_init();
   hid_app_init();
   msc_app_init();
diff --git a/hw/bsp/nrf/boards/feather_nrf52840_express/board.h b/hw/bsp/nrf/boards/feather_nrf52840_express/board.h
index 3d59516d8..22946422b 100644
--- a/hw/bsp/nrf/boards/feather_nrf52840_express/board.h
+++ b/hw/bsp/nrf/boards/feather_nrf52840_express/board.h
@@ -49,8 +49,8 @@
 #define MAX3421_SCK_PIN  14
 #define MAX3421_MOSI_PIN 13
 #define MAX3421_MISO_PIN 15
-#define MAX3421_CS_PIN   27 // D10
-#define MAX3421_INTR_PIN 26 // D9
+#define MAX3421_CS_PIN   6  // D11
+#define MAX3421_INTR_PIN 27 // D10
 
 #ifdef __cplusplus
  }
diff --git a/hw/bsp/nrf/family.c b/hw/bsp/nrf/family.c
index c431389f3..6e0cd85c3 100644
--- a/hw/bsp/nrf/family.c
+++ b/hw/bsp/nrf/family.c
@@ -95,9 +95,7 @@ TU_ATTR_UNUSED static void power_event_handler(nrfx_power_usb_evt_t event) {
 
 //------------- Host using MAX2341E -------------//
 #if CFG_TUH_ENABLED && defined(CFG_TUH_MAX3421) && CFG_TUH_MAX3421
-
 static void max3421_init(void);
-
 static nrfx_spim_t _spi = NRFX_SPIM_INSTANCE(1);
 #endif
 
diff --git a/hw/bsp/samd21/boards/feather_m0_express/board.h b/hw/bsp/samd21/boards/feather_m0_express/board.h
index 8e0caa6bd..fd3d16aaa 100644
--- a/hw/bsp/samd21/boards/feather_m0_express/board.h
+++ b/hw/bsp/samd21/boards/feather_m0_express/board.h
@@ -43,6 +43,21 @@
 #define UART_RX_PIN           4
 #define UART_TX_PIN           5
 
+// SPI for USB host shield
+#define MAX3421_SERCOM_ID       4       // SERCOM4
+#define MAX3421_SERCOM_FUNCTION 3       // function D (Sercom Alt)
+
+#define MAX3421_SCK_PIN         (32+11)
+#define MAX3421_MOSI_PIN        (32+10)
+#define MAX3421_MISO_PIN        12
+#define MAX3421_TX_PAD          1 // MOSI = PAD_2, SCK = PAD_3
+#define MAX3421_RX_PAD          0 // MISO = PAD_2
+
+#define MAX3421_CS_PIN          16      // D11
+
+#define MAX3421_INTR_PIN        18      // D10
+#define MAX3421_INTR_EIC_ID     2       // EIC2
+
 #ifdef __cplusplus
  }
 #endif
diff --git a/hw/bsp/samd51/boards/feather_m4_express/board.h b/hw/bsp/samd51/boards/feather_m4_express/board.h
index 4629643fd..474163c06 100644
--- a/hw/bsp/samd51/boards/feather_m4_express/board.h
+++ b/hw/bsp/samd51/boards/feather_m4_express/board.h
@@ -31,6 +31,8 @@
  extern "C" {
 #endif
 
+#define _PINNUM(port, pin)    ((port)*32 + (pin))
+
 // LED
 #define LED_PIN               23
 #define LED_STATE_ON          1
@@ -43,6 +45,21 @@
 #define UART_TX_PIN           (32 + 17)
 #define UART_RX_PIN           (32 + 16)
 
+// SPI for USB host shield
+#define MAX3421_SERCOM_ID       1  // SERCOM2
+#define MAX3421_SERCOM_FUNCTION 2  // function C
+
+#define MAX3421_SCK_PIN         _PINNUM(0, 17)
+#define MAX3421_MOSI_PIN        _PINNUM(1, 23)
+#define MAX3421_MISO_PIN        _PINNUM(1, 22)
+#define MAX3421_TX_PAD          2 // MOSI = PAD_3, SCK = PAD_1
+#define MAX3421_RX_PAD          2 // MISO = PAD_2
+
+#define MAX3421_CS_PIN          21 // D11
+
+#define MAX3421_INTR_PIN        20 // D10
+#define MAX3421_INTR_EIC_ID     4  // EIC4
+
 #ifdef __cplusplus
  }
 #endif
diff --git a/hw/bsp/samd51/family.c b/hw/bsp/samd51/family.c
index bca18e1a2..009a0d290 100644
--- a/hw/bsp/samd51/family.c
+++ b/hw/bsp/samd51/family.c
@@ -76,12 +76,12 @@ void USB_3_Handler(void) {
 // Implementation
 //--------------------------------------------------------------------+
 
-#if CFG_TUH_ENABLED && defined(CFG_TUH_MAX3421) && CFG_TUH_MAX3421
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
+
 #define MAX3421_SERCOM TU_XSTRCAT(SERCOM, MAX3421_SERCOM_ID)
 #define MAX3421_EIC_Handler TU_XSTRCAT3(EIC_, MAX3421_INTR_EIC_ID, _Handler)
 
 static void max3421_init(void);
-
 #endif
 
 void board_init(void) {
@@ -136,11 +136,14 @@ void board_init(void) {
   gpio_set_pin_function(PIN_PA24, PINMUX_PA24H_USB_DM);
   gpio_set_pin_function(PIN_PA25, PINMUX_PA25H_USB_DP);
 
-#if CFG_TUH_ENABLED && defined(CFG_TUH_MAX3421) && CFG_TUH_MAX3421
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
   max3421_init();
 #endif
 }
 
+void board_init_after_tusb(void) {
+}
+
 //--------------------------------------------------------------------+
 // Board porting API
 //--------------------------------------------------------------------+
@@ -182,7 +185,7 @@ uint32_t board_millis(void) {
 //--------------------------------------------------------------------+
 // API: SPI transfer with MAX3421E, must be implemented by application
 //--------------------------------------------------------------------+
-#if CFG_TUH_ENABLED && defined(CFG_TUH_MAX3421) && CFG_TUH_MAX3421
+#if CFG_TUH_ENABLED && CFG_TUH_MAX3421
 
 static void max3421_init(void) {
   //------------- SPI Init -------------//
@@ -262,7 +265,7 @@ static void max3421_init(void) {
 
   // Enable the SPI module
   sercom->SPI.CTRLA.bit.ENABLE = 1;
-  while (sercom->SPI.SYNCBUSY.bit.ENABLE);
+  while (sercom->SPI.SYNCBUSY.bit.ENABLE) {}
 
   //------------- External Interrupt -------------//
 
diff --git a/src/portable/analog/max3421/hcd_max3421.c b/src/portable/analog/max3421/hcd_max3421.c
index 65f87f7c6..2abd74d51 100644
--- a/src/portable/analog/max3421/hcd_max3421.c
+++ b/src/portable/analog/max3421/hcd_max3421.c
@@ -54,6 +54,12 @@ enum {
   CPUCTL_ADDR   = 16u << 3, // 0x80
   PINCTL_ADDR   = 17u << 3, // 0x88
   REVISION_ADDR = 18u << 3, // 0x90
+  // 19 is not used
+  IOPINS1_ADDR  = 20u << 3, // 0xA0
+  IOPINS2_ADDR  = 21u << 3, // 0xA8
+  GPINIRQ_ADDR  = 22u << 3, // 0xB0
+  GPINIEN_ADDR  = 23u << 3, // 0xB8
+  GPINPOL_ADDR  = 24u << 3, // 0xC0
   HIRQ_ADDR     = 25u << 3, // 0xC8
   HIEN_ADDR     = 26u << 3, // 0xD0
   MODE_ADDR     = 27u << 3, // 0xD8
@@ -207,7 +213,9 @@ typedef struct {
 static max3421_data_t _hcd_data;
 
 //--------------------------------------------------------------------+
-// API: SPI transfer with MAX3421E, must be implemented by application
+// API: SPI transfer with MAX3421E
+// - spi_cs_api(), spi_xfer_api(), int_api(): must be implemented by application
+// - reg_read(), reg_write(): is implemented by this driver, can be used by application
 //--------------------------------------------------------------------+
 
 // API to control MAX3421 SPI CS
@@ -220,11 +228,18 @@ extern bool tuh_max3421_spi_xfer_api(uint8_t rhport, uint8_t const* tx_buf, uint
 // API to enable/disable MAX3421 INTR pin interrupt
 extern void tuh_max3421_int_api(uint8_t rhport, bool enabled);
 
+// API to read MAX3421's register. Implemented by TinyUSB
+uint8_t tuh_max3421_reg_read(uint8_t rhport, uint8_t reg, bool in_isr);
+
+// API to write MAX3421's register. Implemented by TinyUSB
+bool tuh_max3421_reg_write(uint8_t rhport, uint8_t reg, uint8_t data, bool in_isr);
+
 //--------------------------------------------------------------------+
-// SPI Helper
+// SPI Commands and Helper
 //--------------------------------------------------------------------+
-static void handle_connect_irq(uint8_t rhport, bool in_isr);
-static inline void hirq_write(uint8_t rhport, uint8_t data, bool in_isr);
+
+#define reg_read  tuh_max3421_reg_read
+#define reg_write tuh_max3421_reg_write
 
 static void max3421_spi_lock(uint8_t rhport, bool in_isr) {
   // disable interrupt and mutex lock (for pre-emptive RTOS) if not in_isr
@@ -248,6 +263,32 @@ static void max3421_spi_unlock(uint8_t rhport, bool in_isr) {
   }
 }
 
+uint8_t tuh_max3421_reg_read(uint8_t rhport, uint8_t reg, bool in_isr) {
+  uint8_t tx_buf[2] = {reg, 0};
+  uint8_t rx_buf[2] = {0, 0};
+
+  max3421_spi_lock(rhport, in_isr);
+  bool ret = tuh_max3421_spi_xfer_api(rhport, tx_buf, rx_buf, 2);
+  max3421_spi_unlock(rhport, in_isr);
+
+  _hcd_data.hirq = rx_buf[0];
+  return ret ? rx_buf[1] : 0;
+}
+
+bool tuh_max3421_reg_write(uint8_t rhport, uint8_t reg, uint8_t data, bool in_isr) {
+  uint8_t tx_buf[2] = {reg | CMDBYTE_WRITE, data};
+  uint8_t rx_buf[2] = {0, 0};
+
+  max3421_spi_lock(rhport, in_isr);
+  bool ret = tuh_max3421_spi_xfer_api(rhport, tx_buf, rx_buf, 2);
+  max3421_spi_unlock(rhport, in_isr);
+
+  // HIRQ register since we are in full-duplex mode
+  _hcd_data.hirq = rx_buf[0];
+
+  return ret;
+}
+
 static void fifo_write(uint8_t rhport, uint8_t reg, uint8_t const * buffer, uint16_t len, bool in_isr) {
   uint8_t hirq;
   reg |= CMDBYTE_WRITE;
@@ -275,34 +316,7 @@ static void fifo_read(uint8_t rhport, uint8_t * buffer, uint16_t len, bool in_is
   max3421_spi_unlock(rhport, in_isr);
 }
 
-static void reg_write(uint8_t rhport, uint8_t reg, uint8_t data, bool in_isr) {
-  uint8_t tx_buf[2] = {reg | CMDBYTE_WRITE, data};
-  uint8_t rx_buf[2] = {0, 0};
-
-  max3421_spi_lock(rhport, in_isr);
-
-  tuh_max3421_spi_xfer_api(rhport, tx_buf, rx_buf, 2);
-
-  max3421_spi_unlock(rhport, in_isr);
-
-  // HIRQ register since we are in full-duplex mode
-  _hcd_data.hirq = rx_buf[0];
-}
-
-static uint8_t reg_read(uint8_t rhport, uint8_t reg, bool in_isr) {
-  uint8_t tx_buf[2] = {reg, 0};
-  uint8_t rx_buf[2] = {0, 0};
-
-  max3421_spi_lock(rhport, in_isr);
-
-  bool ret = tuh_max3421_spi_xfer_api(rhport, tx_buf, rx_buf, 2);
-
-  max3421_spi_unlock(rhport, in_isr);
-
-  _hcd_data.hirq = rx_buf[0];
-  return ret ? rx_buf[1] : 0;
-}
-
+//------------- register write helper -------------//
 static inline void hirq_write(uint8_t rhport, uint8_t data, bool in_isr) {
   reg_write(rhport, HIRQ_ADDR, data, in_isr);
   // HIRQ write 1 is clear