diff --git a/drivers/cyw43/cywbt.c b/drivers/cyw43/cywbt.c
new file mode 100644
index 000000000..111cff158
--- /dev/null
+++ b/drivers/cyw43/cywbt.c
@@ -0,0 +1,222 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "pin_static_af.h"
+#include "uart.h"
+#include "cywbt.h"
+#include "nimble/hci_uart.h"
+
+#if MICROPY_PY_NETWORK_CYW43
+
+extern const char fw_4343WA1_7_45_98_50_start;
+#define CYWBT_FW_ADDR (&fw_4343WA1_7_45_98_50_start + 749 * 512 + 29 * 256)
+
+/******************************************************************************/
+// CYW BT HCI low-level driver
+
+static void cywbt_wait_cts_low(void) {
+    mp_hal_pin_config(pyb_pin_BT_CTS, MP_HAL_PIN_MODE_INPUT, MP_HAL_PIN_PULL_UP, 0);
+    for (int i = 0; i < 200; ++i) {
+        if (mp_hal_pin_read(pyb_pin_BT_CTS) == 0) {
+            break;
+        }
+        mp_hal_delay_ms(1);
+    }
+    mp_hal_pin_config_alt_static(pyb_pin_BT_CTS, MP_HAL_PIN_MODE_ALT, MP_HAL_PIN_PULL_UP, STATIC_AF_USART6_CTS);
+}
+
+static int cywbt_hci_cmd_raw(size_t len, uint8_t *buf) {
+    uart_tx_strn(&bt_hci_uart_obj, (void*)buf, len);
+    for (int i = 0; i < 6; ++i) {
+        while (!uart_rx_any(&bt_hci_uart_obj)) {
+            MICROPY_EVENT_POLL_HOOK
+        }
+        buf[i] = uart_rx_char(&bt_hci_uart_obj);
+    }
+
+    // expect a comand complete event (event 0x0e)
+    if (buf[0] != 0x04 || buf[1] != 0x0e) {
+        printf("unknown response: %02x %02x %02x %02x\n", buf[0], buf[1], buf[2], buf[3]);
+        return -1;
+    }
+
+    /*
+    if buf[3:6] != cmd[:3]:
+        print('response doesn\'t match cmd:', cmd, ev)
+        return b''
+        */
+
+    int sz = buf[2] - 3;
+    for (int i = 0; i < sz; ++i) {
+        while (!uart_rx_any(&bt_hci_uart_obj)) {
+            MICROPY_EVENT_POLL_HOOK
+        }
+        buf[i] = uart_rx_char(&bt_hci_uart_obj);
+    }
+
+    return 0;
+}
+
+static int cywbt_hci_cmd(int ogf, int ocf, size_t param_len, const uint8_t *param_buf) {
+    uint8_t *buf = bt_hci_cmd_buf;
+    buf[0] = 0x01;
+    buf[1] = ocf;
+    buf[2] = ogf << 2 | ocf >> 8;
+    buf[3] = param_len;
+    if (param_len) {
+        memcpy(buf + 4, param_buf, param_len);
+    }
+    return cywbt_hci_cmd_raw(4 + param_len, buf);
+}
+
+static void put_le16(uint8_t *buf, uint16_t val) {
+    buf[0] = val;
+    buf[1] = val >> 8;
+}
+
+static void put_le32(uint8_t *buf, uint32_t val) {
+    buf[0] = val;
+    buf[1] = val >> 8;
+    buf[2] = val >> 16;
+    buf[3] = val >> 24;
+}
+
+static int cywbt_set_baudrate(uint32_t baudrate) {
+    uint8_t buf[6];
+    put_le16(buf, 0);
+    put_le32(buf + 2, baudrate);
+    return cywbt_hci_cmd(0x3f, 0x18, 6, buf);
+}
+
+// download firmware
+static int cywbt_download_firmware(const uint8_t *firmware) {
+    cywbt_hci_cmd(0x3f, 0x2e, 0, NULL);
+
+    bool last_packet = false;
+    while (!last_packet) {
+        uint8_t *buf = bt_hci_cmd_buf;
+        memcpy(buf + 1, firmware, 3);
+        firmware += 3;
+        last_packet = buf[1] == 0x4e;
+        if (buf[2] != 0xfc) {
+            printf("fail1 %02x\n", buf[2]);
+            break;
+        }
+        uint8_t len = buf[3];
+
+        memcpy(buf + 4, firmware, len);
+        firmware += len;
+
+        buf[0] = 1;
+        cywbt_hci_cmd_raw(4 + len, buf);
+        if (buf[0] != 0) {
+            printf("fail3 %02x\n", buf[0]);
+            break;
+        }
+    }
+
+    // RF switch must select high path during BT patch boot
+    mp_hal_pin_config(pyb_pin_WL_GPIO_1, MP_HAL_PIN_MODE_INPUT, MP_HAL_PIN_PULL_UP, 0);
+    mp_hal_delay_ms(10); // give some time for CTS to go high
+    cywbt_wait_cts_low();
+    mp_hal_pin_config(pyb_pin_WL_GPIO_1, MP_HAL_PIN_MODE_INPUT, MP_HAL_PIN_PULL_DOWN, 0); // Select chip antenna (could also select external)
+
+    nimble_hci_uart_set_baudrate(115200);
+    cywbt_set_baudrate(3000000);
+    nimble_hci_uart_set_baudrate(3000000);
+
+    return 0;
+}
+
+int cywbt_init(void) {
+    // This is called from Nimble via hal_uart_config which will have already initialized the UART.
+
+    mp_hal_pin_output(pyb_pin_BT_REG_ON);
+    mp_hal_pin_low(pyb_pin_BT_REG_ON);
+    mp_hal_pin_input(pyb_pin_BT_HOST_WAKE);
+    mp_hal_pin_output(pyb_pin_BT_DEV_WAKE);
+    mp_hal_pin_low(pyb_pin_BT_DEV_WAKE);
+
+    // TODO don't select antenna if wifi is enabled
+    mp_hal_pin_config(pyb_pin_WL_GPIO_4, MP_HAL_PIN_MODE_OUTPUT, MP_HAL_PIN_PULL_NONE, 0); // RF-switch power
+    mp_hal_pin_high(pyb_pin_WL_GPIO_4); // Turn the RF-switch on
+
+    return 0;
+}
+
+int cywbt_activate(void) {
+    uint8_t buf[256];
+
+    mp_hal_pin_low(pyb_pin_BT_REG_ON);
+    nimble_hci_uart_set_baudrate(115200);
+    mp_hal_delay_ms(100);
+    mp_hal_pin_high(pyb_pin_BT_REG_ON);
+    cywbt_wait_cts_low();
+
+    // Reset
+    cywbt_hci_cmd(0x03, 0x0003, 0, NULL);
+
+    // Change baudrate
+    cywbt_set_baudrate(3000000);
+    nimble_hci_uart_set_baudrate(3000000);
+
+    cywbt_download_firmware((const uint8_t*)CYWBT_FW_ADDR);
+
+    // Reset
+    cywbt_hci_cmd(0x03, 0x0003, 0, NULL);
+
+    // Set BD_ADDR (sent as little endian)
+    uint8_t bdaddr[6];
+    mp_hal_get_mac(MP_HAL_MAC_BDADDR, bdaddr);
+    buf[0] = bdaddr[5];
+    buf[1] = bdaddr[4];
+    buf[2] = bdaddr[3];
+    buf[3] = bdaddr[2];
+    buf[4] = bdaddr[1];
+    buf[5] = bdaddr[0];
+    cywbt_hci_cmd(0x3f, 0x0001, 6, buf);
+
+    // Set local name
+    // memset(buf, 0, 248);
+    // memcpy(buf, "PYBD-BLE", 8);
+    // cywbt_hci_cmd(0x03, 0x0013, 248, buf);
+
+    // Configure sleep mode
+    cywbt_hci_cmd(0x3f, 0x27, 12, (const uint8_t*)"\x01\x02\x02\x00\x00\x00\x01\x00\x00\x00\x00\x00");
+
+    // HCI_Write_LE_Host_Support
+    cywbt_hci_cmd(3, 109, 2, (const uint8_t*)"\x01\x00");
+
+    mp_hal_pin_high(pyb_pin_BT_DEV_WAKE); // let sleep
+
+    return 0;
+}
+
+#endif
diff --git a/drivers/cyw43/cywbt.h b/drivers/cyw43/cywbt.h
new file mode 100644
index 000000000..9809d7f41
--- /dev/null
+++ b/drivers/cyw43/cywbt.h
@@ -0,0 +1,35 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_DRIVERS_CYW43_CYWBT_H
+#define MICROPY_INCLUDED_DRIVERS_CYW43_CYWBT_H
+
+extern uint8_t bt_hci_cmd_buf[4 + 256];
+extern pyb_uart_obj_t bt_hci_uart_obj;
+
+int cywbt_init(void);
+int cywbt_activate(void);
+
+#endif // MICROPY_INCLUDED_DRIVERS_CYW43_CYWBT_H