QUERY · ISSUE

ESP32: Setting Bluetooth TX power when initalizing BLE

openby ctschachopened 2021-12-20updated 2026-01-13

port-esp32

I had trouble connecting to a Bluetooth master running on an ESP32. After about 4m I couldn't get a reliable connection anymore.

After trying out different ESP32's and external antennas, I run across the following forum post:

https://forum.micropython.org/viewtopic.php?t=7733#p62651

He is increasing the Bluetooth power directly in the init function with the following two commands:

    esp_ble_tx_power_set(ESP_BLE_PWR_TYPE_DEFAULT, ESP_PWR_LVL_P9);
    esp_ble_tx_power_set(ESP_BLE_PWR_TYPE_ADV, ESP_PWR_LVL_P9);

And that actually solved the problem. Not sure what the default Bluetooth TX power is, but would there be a chance that you can set the TX power from the bluetooth init-function inside of MicroPython?

CANDIDATE · ISSUE

[ESP32-S3] BLE.init() interrupts serial output

closedby n-eliaopened 2022-06-10updated 2022-07-06

bug

Hi,
I'm running MicroPython v1.18 on a ESP32-S3 based board (Unexpected Maker TinyS3). I'm using the onboard USB to get a remote REPL.

We're successfully running a firmware on older ESP32 boards and, after moving to the new ESP32-S3, the method bluetooth.active() appears to break the serial connection.

To quickly reproduce the issue:

# main.py
import bluetooth

ble = bluetooth.BLE()
print("Activating BLE...")
ble.active(True)
print("Activated BLE.")

Output:

MPY: soft reboot
Activating BLE...

Expected output (from an older ESP32 board):

MPY: soft reboot
Activating BLE...
Activated BLE.
MicroPython v1.18 on 2022-01-17; ESP32 module with ESP32
Type "help()" for more information.
>>>

As you may see, after executing bluetooth.active() the connection hangs. The terminal becomes unresponsive (tried with rshell, picocom, Thonny IDE) and the only way to re-gain the control is to have a sleep statement at the beginning of the script and to hard reset the board.

This was tested at least on the following builds:

Nightly builds
[v1.18-610-gcf7d962cf (2022-06-10) .uf2](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-610-gcf7d962cf.uf2) [[.bin]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-610-gcf7d962cf.bin) [[.elf]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-610-gcf7d962cf.elf) [[.map]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-610-gcf7d962cf.map)
[v1.18-605-gee9feacc0 (2022-06-10) .uf2](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-605-gee9feacc0.uf2) [[.bin]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-605-gee9feacc0.bin) [[.elf]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-605-gee9feacc0.elf) [[.map]](https://micropython.org/resources/firmware/tinys3-20220610-unstable-v1.18-605-gee9feacc0.map)
[v1.18-602-gf63b4f85a (2022-06-09) .uf2](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-602-gf63b4f85a.uf2) [[.bin]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-602-gf63b4f85a.bin) [[.elf]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-602-gf63b4f85a.elf) [[.map]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-602-gf63b4f85a.map)
[v1.18-601-g3452ee58d (2022-06-09) .uf2](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-601-g3452ee58d.uf2) [[.bin]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-601-g3452ee58d.bin) [[.elf]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-601-g3452ee58d.elf) [[.map]](https://micropython.org/resources/firmware/tinys3-20220609-unstable-v1.18-601-g3452ee58d.map)

<details>
<summary>Firmware which caused the problem</summary>

# main.py
import sys
import time
import uasyncio
import bluetooth

from ble_advertising import decode_name

_IRQ_SCAN_RESULT = const(5)
_IRQ_SCAN_DONE = const(6)


async def main_loop():
    ble_coro_handle = uasyncio.create_task(ble_coro())
    await uasyncio.sleep(5)


async def ble_coro():
    ble = bluetooth.BLE()
    print("Activating BLE...")
    ble.active(True)
    print("Activated BLE.")
    ble.irq(irq_handler)
    try:
        ble.gap_scan(0, 30000, 30000)
        while True:
            await uasyncio.sleep(5)

    except uasyncio.CancelledError:
        ble.gap_scan(None)
        print("ble_coro: task cleaned up")
        
  
def irq_handler(self, event, data):
    if event == _IRQ_SCAN_RESULT:
        addr_type, addr, adv_type, rssi, adv_data = data
        device_name = decode_name(adv_data) or 'unknown'
        device_rssi = int(rssi)
        ts = time.time()
        print(f"Found device with name {device_name}, RSSI {device_rssi}, at time {str(ts)}")

    elif event == _IRQ_SCAN_DONE:
        print("Scan cycle terminated.")


if __name__ == "__main__":
    try:
        uasyncio.run(main_loop())
    except KeyboardInterrupt:
        print('Interrupted')
    finally:
        uasyncio.new_event_loop()

# ble_advertising.py
from micropython import const
import struct

_ADV_TYPE_NAME = const(0x09)

def decode_field(payload, adv_type):
    i = 0
    result = []
    while i + 1 < len(payload):
        if payload[i + 1] == adv_type:
            result.append(payload[i + 2 : i + payload[i] + 1])
        i += 1 + payload[i]
    return result

def decode_name(payload):
    n = decode_field(payload, _ADV_TYPE_NAME)
    return str(n[0], "utf-8") if n else ""

</details>

Thanks for your help.