As I said, I am using a SiPy board with:

(sysname='SiPy', nodename='SiPy', release='1.6.13.b1', version='v1.8.6-607-g9c8a0e9e on 2017-05-01', machine='SiPy with ESP32', sigfox='1.0.1')

The boot.py file sets up the WiFi connection:

from machine import UART
import os
uart = UART(0, 115200)
os.dupterm(uart)

import machine
from network import WLAN

wlan = WLAN(mode=WLAN.STA)
nets = wlan.scan()
for net in nets:
    if net.ssid == 'NetName':
        wlan.connect(net.ssid, auth=(net.sec, 'Password'), timeout=5000)
        while not wlan.isconnected():
            machine.idle()
        break

The main.py program is based in the examples in the documentation shown here, here and this forum topic.

from network import Bluetooth
import binascii
import time
import urequests
import gc

def digit_to_char(digit):
    if digit < 10: return chr(ord('0') + digit)
    else: return chr(ord('a') + digit - 10)

def str_base(number,base):
    if number < 0:
        return '-' + str_base(-number,base)
    else:
        (d,m) = divmod(number,base)
        if d:
            return str_base(d,base) + digit_to_char(m)
        else:
            return digit_to_char(m)

def password_generate(deviceID):
    a=devID[0]^0x50
    b=devID[1]^0x50
    c=devID[2]^0x50
    d=devID[3]^0x50
    e=devID[4]^0x50
    f=devID[5]^0x50
    g=devID[6]^0x50
    h=devID[7]^0x50

    password=a
    password=(password<<8)+b
    password=(password<<8)+c
    password=(password<<8)+d
    password=(password<<8)+e
    password=(password<<8)+f
    password=(password<<8)+g
    password=(password<<8)+h

    PASSb16=str_base(password, 16)

    return PASSb16

while True:
    bluetooth = Bluetooth()
    devID=0
    bluetooth.start_scan(-1)
    adv = None

    while True:
        adv = bluetooth.get_adv()
        if adv and bluetooth.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'DeviceName': 
            try:
                conn=bluetooth.connect(adv.mac)
                services = conn.services()
                
                for service in services:
                    time.sleep(0.050)
                    service.uuid()
                    chars = service.characteristics()
                    for char in chars:
                        if (char.properties() & Bluetooth.PROP_READ):
                            char.uuid()
                            if (char.uuid() == 10787):
                                devID=char.read()
                                print('DeviceID = {}'.format(binascii.hexlify(devID)))
                                pword=password_generate(devID)
                            if devID:
                                if (char.uuid() == 65521):
                                    char.write(binascii.unhexlify(pword))
                                    char1= binascii.hexlify(char.read())
                                    print('MagRead = '+str(char1))
                                    urequests.request("POST","http://requestb.in/1csszaw1",'{"DeviceID":'+str(binascii.hexlify(devID))+',"MagRead":'+str(char1)+'}').text
                break
            except:
                bluetooth.start_scan(-1)
                continue
            break
    bluetooth.stop_scan()
    conn.disconnect()
    gc.collect()

Running the program I got constant Guru Meditation Errors or freezes, so I decided to change the program so that it could connect to any device; going from:

 while True:
        adv = bluetooth.get_adv()
        if adv and bluetooth.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'DeviceName': 
            try:

to:

 while True:
        adv = bluetooth.get_adv()
        if adv: 
            try:

This worked better but I still got the same problems as before.

I then reduced the program to it basic functionality to find where exactly it was failing.

from network import Bluetooth
import time
import gc

bluetooth = Bluetooth()
while True:
    bluetooth.start_scan(-1)
    adv = None
    while True:
        time.sleep(0.3)
        print('1')
        adv = bluetooth.get_adv()
        if adv and bluetooth.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'DeviceName':
            print('22')
            try:
                print('333')
                conn=bluetooth.connect(adv.mac)
                print('4444')
                services = conn.services()
                print('55555')
            except:
                print('AAAAAA')
                bluetooth.start_scan(-1)
                continue
            break
    conn.disconnect()
    bluetooth.stop_scan()
    gc.collect()

I found that most of the time the program would fail when trying to connect to the device or read the services. It also got stuck several times in the if statement not finding a device even when there was one advertising. It would also connect to the device and freeze, and after a soft reboot it would stay connected to the device.

Am I doing something incorrectly? Should I try to optimize it further? Or is it a firmware/hardware issue?

if adv and bluetooth.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'DeviceName':
            print('22')
            try:
                bluetooth.stop_scan()
                print('333')

Any chance you could share a snippet of working code?

Thanks

The full program works like this:

Running main.py
BTDM CONTROLLER VERSION: 010101
BTDM ROM VERSION 0101
BD_ADDR: 24:0A:C4:00:FA:CA
NVDS MAGIC FAILED
RF Init OK with coex
Enable Classic BT
Enable Low Energy
DeviceID = b'28dbafedff3ace00'
MagRead = b'2e'

After the first successful connection it gets stuck and doesn't connect to anything.

The simplified version of the program:

Running main.py
BTDM CONTROLLER VERSION: 010101
BTDM ROM VERSION 0101
BD_ADDR: 24:0A:C4:00:FA:CA
NVDS MAGIC FAILED
RF Init OK with coex
Enable Classic BT
Enable Low Energy
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
22
333
4444
AAAAAA
1
1
1
1
1
1
1
22
333
4444
AAAAAA
1
22
333
4444
AAAAAA
1
1
1
22
333
4444
55555
1
1
1
1
1
1
1
1
1
1
1
1
1
ASSERT_PARAM(10 0), in lld_pdu.c at line 1260