Toit
#BLE Connection to device which does not advertise any services
Thread channel in help
z3ugma 01/08/2023 05:57 AM
I'm trying to communicate with a ring-based pulse oximeter which does not advertise any services. when calling
I know the service UUID, and the UUID of the characteristics I'm interested in. Can I skip straight to exchanging write/notify data from the characteristics?
Service data from LightBlue screenshots are attached
import ble
DEV_NAME ::= "O2Ring"
SCAN_DURATION ::= Duration --s=3
find_by_name central/ble.Central name/string:
central.scan --duration=SCAN_DURATION: | device/ble.RemoteScannedDevice |
if device.data.name and device.data.name.contains name:
return device.address
throw "no ring device found"
main:
adapter := ble.Adapter
central := adapter.central
address := find_by_name central DEV_NAME
remote_device := central.connect address
print remote_device.address
services := remote_device.discover_services
//0x0d BLE_HS_ETIMEOUT Operation timed out.
// EXCEPTION error.
// NimBLE error, Type: host, error code: 0x0d. See https://gist.github.com/mikkeldamsgaard/0857ce6a8b073a52...
// 0: ble_get_error_ <sdk>/ble.toit:980:3
// 1: Resource_.throw_error_ <sdk>/ble.toit:811:5I'm trying to communicate with a ring-based pulse oximeter which does not advertise any services. when calling
discover_servicesI know the service UUID, and the UUID of the characteristics I'm interested in. Can I skip straight to exchanging write/notify data from the characteristics?
Service data from LightBlue screenshots are attached
floitsch 01/08/2023 01:24 PM
I don't have a device to test this on, bit maybe it works if you provide the IDs during discovery.
@MikkelD might know exactly what to do.
MikkelD 01/08/2023 02:32 PM
The BLE protocol requires you to discover the services. They do not need to be advertised to be discovered.
MikkelD 01/08/2023 02:39 PM
One thing we havent done quite yet, is pairing on BLE on esp32. So if the oring requires the device to be paired, then this is something that could easily happen.
MikkelD 01/08/2023 02:39 PM
If you have the possibility to try it on mac, then the mac can pair and you can then see if it works.
z3ugma 01/08/2023 02:57 PM
I do have this currently working on macOS in a Python program, let me post some snippets!
z3ugma 01/08/2023 02:58 PM
https://github.com/z3ugma/o2r
def on_detection(self, device, advertisement_data):
if device.address not in self.devices:
name = device.name or device.address
uuids = device.metadata["uuids"] if "uuids" in device.metadata else None
if self.verbose > 4 and device.address not in self.pipe_down:
print(f"Considering {device.address} {name} {uuids}")
self.pipe_down.append(device.address)
valid = False
if uuids is not None and BLE_MATCH_UUID in uuids and BLE_SERVICE_UUID in uuids:
valid = True
else:
# We might not have the list of UUIDs yet, so also check by name
names = ("Checkme_O2", "CheckO2", "SleepU", "SleepO2", "O2Ring", "WearO2", "KidsO2", "BabyO2", "Oxylink")
for n in names:
if n in name:
if self.verbose > 1:
print(f"Found device by name: {n}")
valid = True
break
if not valid:
return
print(f"Adding device {device.address}")
dev = O2BTDevice(address_or_ble_device=device, timeout=10.0, disconnected_callback=O2BTDevice.on_disconnect)
z3ugma 01/08/2023 02:59 PM
async def _go_get_services(self):
if self.disconnect_pending or not self.is_connected:
return
# services = await self.get_services()
if self.manager.verbose > 1:
print(f"[{self.name}] Resolved services")
for service in self.services:
print(f"[{self.name}]\tService [{service.uuid}]")
for characteristic in service.characteristics:
print(f"[{self.name}]\t\tCharacteristic [{characteristic.uuid}]")
for descriptor in characteristic.descriptors:
value = await self.read_gatt_descriptor(descriptor.handle)
print(f"[{self.name}]\t\t\tDescriptor [{descriptor.uuid}] ({value})")
for s in self.services:
if s.uuid == BLE_SERVICE_UUID:
for c in s.characteristics:
if c.uuid == BLE_READ_UUID:
asyncio.ensure_future(self._go_enable_notifications(c))
elif c.uuid == BLE_WRITE_UUID:
self.write = cz3ugma 01/08/2023 03:03 PM@MikkelD afaik it doesn't require pairing.
With Python using
With Python using
bleakconnectz3ugma 01/08/2023 03:15 PM
selfBleakClientclass BleakClient:
"""The Client interface for connecting to a specific BLE GATT server and communicating with it.
A BleakClient can be used as an asynchronous context manager in which case it automatically
connects and disconnects.z3ugma 01/08/2023 03:19 PM
inside of the macOS
bleak/backends/corebluetooth/PeripheralDelegate.pyperipheral.discoverServices_(None)CoreBluetoothz3ugma 01/08/2023 03:22 PM
But when I call
^^ I get the commented error, of a bluetooth timeout
discover_servicesremote_device := central.connect address
print remote_device.address
services := remote_device.discover_services
//0x0d BLE_HS_ETIMEOUT Operation timed out.
// EXCEPTION error.
// NimBLE error, Type: host, error code: 0x0d. See https://gist.github.com/mikkeldamsgaard/0857ce6a8b073a52...
// 0: ble_get_error_ <sdk>/ble.toit:980:3
// 1: Resource_.throw_error_ <sdk>/ble.toit:811:5^^ I get the commented error, of a bluetooth timeout
z3ugma 01/08/2023 04:02 PM
or @MikkelD did you mean to try to run the Toit code on macOS instead of on the ESP32 itself
OPz3ugmaor @MikkelD did you mean to try to run the Toit code on macOS instead of on the ESP32 itself
floitsch 01/08/2023 04:28 PM
I think that's what he meant, but it's probably helpful to have the python code as well
z3ugma 01/08/2023 04:32 PM@floitsch the tutorials show how to run jag on Mac and then send the code to ESP32. Is there documentation of how to run toit code directly on Mac
floitsch 01/08/2023 04:33 PMSpeed up literal byte array parsing containing chars.
Allow UART interrupt priority to be higher.
Add every and any methods to Map.
Move ESP32 TCP buffers on-heap.
Use string slice for trim, so str... 
I'm not sure if we have a 'brew' for Toit directly, but you can download the binaries from here: https://github.com/toitlang/toit/releases/tag/v2.0.0-alpha.47
Allow UART interrupt priority to be higher.
Add every and any methods to Map.
Move ESP32 TCP buffers on-heap.
Use string slice for trim, so str...
floitsch 01/08/2023 04:33 PM
Then use
toit.runfloitsch 01/08/2023 04:34 PM
Alternatively, you could also use the SDK that Jaguar downloads.
floitsch 01/08/2023 04:34 PM
(It's actually the exactly same archive).
floitsch 01/08/2023 04:35 PM
Jaguar stores its version of the SDK in
~/.cache/jaguar/sdkfloitsch 01/08/2023 04:35 PM
You would have a
toit.run~/.cache/jaguar/sdk/bin/toit.runfloitsch 01/08/2023 04:35 PM
Ooh. And I forgot. You can just ask Jaguar to run code locally with
-d hostjag run -d host foo.toitfloitsch 01/08/2023 04:36 PM
That's clearly the easiest.
z3ugma 01/08/2023 04:42 PM
that works without throwing the timeout exception(edited)
jag run -d host blescan.toit
cm started
B6DF069F-1B4D-A7B1-984A-FAFC71D6760Athat works without throwing the timeout exception(edited)
z3ugma 01/08/2023 04:43 PM
if I add a call to
print servicesjag run -d host blescan.toit
cm started
B6DF069F-1B4D-A7B1-984A-FAFC71D6760A
[an instance with class-id 47, an instance with class-id 47, an instance with class-id 47]floitsch 01/08/2023 04:45 PM
That's good data. Looks like the ESP32 implementation seems to behave differently. Let's hope Mikkel (who wrote the BLE implementation) knows what to do next.
Thanks for all the testing.
Thanks for all the testing.
floitsch 01/08/2023 04:50 PM
Fyi: the
We don't store the class names in the executable, to keep the executables smaller.
If you wanted to get the name of the class, you would need to do the following steps:
1. compile the program to a snapshot:
2. use toitp to print all class-ids:
We already discussed that Jaguar (
an instance with class-id 47stringifyWe don't store the class names in the executable, to keep the executables smaller.
If you wanted to get the name of the class, you would need to do the following steps:
1. compile the program to a snapshot:
~/.cache/jaguar/sdk/bin/toit.compile -w /tmp/out.snapshot your_program.toit2. use toitp to print all class-ids:
~/.cache/jaguar/sdk/tools/toitp -c /tmp/out.snapshotWe already discussed that Jaguar (
jag runan instance with class-id XXz3ugma 01/08/2023 04:54 PM
Thanks for your help too! I guess this is interesting that I can try to get the rest of the program, e.g. the writing and receiving notifications from characteristics, using the mac bluetooth radio, until we get to the bottom of the ESP32 BLE stack
floitsch 01/08/2023 04:54 PM
That should work. And makes development faster.
MikkelD 01/08/2023 06:35 PM
Ok. Thanks for that. I believe the python library does the service discovery for you, there is no way for you to communicate with a peripheral without having discovered the services and set up the shorthands for services and characteristics. It might seem that the NimBLE stack has a timeout that needs to be addressed.
z3ugma 01/08/2023 06:44 PM@MikkelD the timeout for the call on esp32 took about 20-30 sec. Running the toit code on macOS discovers the service right away
MikkelD 01/08/2023 07:00 PM
Yes, NimBLE has a hard timeout of 30 seconds. The timeout occurs because there was no perceived response by the NimBLE stack within that time frame. What causes the response to be lost is a bit more unclear. In our experience the default TX power of the bluetooth stack on ESP32 only allows for 3-4 meters of distance, whereas the mac can reach 30 meters or so. Is your ESP32 close to the peripheral?
z3ugma 01/08/2023 07:03 PM
Yep! 1-2m. It’s a pulse oximeter worn on a finger
z3ugma 01/08/2023 07:04 PM
Any logging or instrumentation that I can do, or increasing verbosity, to give you all better traceability?
MikkelD 01/08/2023 07:28 PM
I have been looking through the code and unfortunately there is not a lot I can do. I hand over the discovery request to NimBLE library that hands it over to the HW and no response comes back. I was wondering if it is an underlying incompatibility between ESP32 (4.2 BLE) and the ORing. What specs does the ORIng has on the BLE?
z3ugma 01/08/2023 08:18 PM
This is interesting to go on. I wonder if I can try making a toy example that works in C++ / Arduino that exhibits the same behavior using NimBLE directly.
z3ugma 01/08/2023 08:19 PM
From what I can find online it’s BLE 4.0 compatible
z3ugma 01/08/2023 08:20 PMSmart Ring Pulse Oximeter Makes You Sleep with Peace of Mind. Tracks Your Oxygen Levels and Heart Rates Overnight. Print or Share Sleep Oximetry Reports. Supports both Android, iOS app and PC Software. 
Embedded on this page https://getwellue.com/pages/o2ring-oxygen-monitor
floitsch 01/08/2023 08:21 PMAnswers checklist. I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there. I have updated my IDF branch (master or release) to the latest version and checked t... 
Could be this? https://github.com/espressif/esp-idf/issues/10109
floitsch 01/08/2023 08:22 PM
or related.
z3ugma 01/08/2023 08:32 PM
1
Maybe related. This issue says that esp-idf is working with the o2ring model. I think my next steps are to try a nimble and an esp-idf example to see if I can list the services without a timeout
1MikkelD 01/08/2023 09:28 PM
Ok, I just oredered a O2ring, so I can debug that properly.
floitsch 01/08/2023 09:29 PM
I hope you have other uses for it as well 
z3ugma 01/08/2023 09:30 PM
MikkelD 01/08/2023 09:34 PM
Not really. But I can find someone who has
z3ugma 01/08/2023 09:38 PM
they're useful for CPAP / sleep apnea patients... that's my use case
z3ugma 01/08/2023 10:12 PMWorking O2Ring NimBLE sample. GitHub Gist: instantly share code, notes, and snippets. 
1
https://gist.github.com/z3ugma/b50fc6f2cd40729302e8a8c863e13729
Made a gist with a working Arduino BLE example that uses NimBLE.
It connects to the O2Ring, discovers the service of interest, and lists the
Made a gist with a working Arduino BLE example that uses NimBLE.
It connects to the O2Ring, discovers the service of interest, and lists the
write1MikkelD 01/09/2023 07:45 AM
Cool, we now know the HW is not at fault. What happens if you comment this out:
#ifdef ESP_PLATFORM
NimBLEDevice::setPower(ESP_PWR_LVL_P9); /** +9db */
#else
NimBLEDevice::setPower(9); /** +9db */
#endifz3ugma 01/09/2023 06:39 PM@MikkelD commented out those lines and flashed to ESP32, same result
z3ugma 01/09/2023 06:39 PM
⸮⸮�⸮�⸮⸮⸮�⸮���⸮�⸮⸮⸮⸮⸮�⸮⸮�������������⸮���⸮��������⸮��������⸮�⸮⸮⸮�⸮⸮�⸮⸮��⸮�⸮⸮��⸮���⸮⸮�⸮�⸮⸮�⸮f%$6⸮0P\⸮'⸮⸮�E (243) esp_core_dump_flash: a⸮ֽ⸮ɕ⸮сsize of core dump image: 0
Starting NimBLE Client
Advertised Device found: Name: , Address: c5:d2:2d:0f:1f:0c, manufacturer data: 4c0012020002
Advertised Device found: Name: O2Ring 0543, Address: c6:d1:08:ef:8a:4d, manufacturer data: 4ef300
Found Our Service
Scan Ended
New client created
Connected
Connected to: c6:d1:08:ef:8a:4d
RSSI: -54
Found our write characteristic
8b00ace7-eb0b-49b0-bbe9-9aee0a26e1a3
Done with this device!
Success! we should now be getting notifications, scanning for more!MikkelD 01/09/2023 06:39 PM
Ok. Thanks.
MikkelD 01/09/2023 07:45 PM
It is a bit weird. I have checked the Arduino implementation against our implementation and they are quite identical. Could you turn on debug logging in the Arduino lib, so we get all the NIMBLE_LOGD's from the implementation?
MikkelD 01/09/2023 07:47 PM
#define CONFIG_NIMBLE_CPP_LOG_LEVEL 4z3ugma 01/09/2023 08:55 PMWorking O2Ring NimBLE sample. GitHub Gist: instantly share code, notes, and snippets.
By turning up the
https://gist.github.com/z3ugma/b50fc6f2cd40729302e8a8c863e13729#file-console_debug-log
CoreDEBUGhttps://gist.github.com/z3ugma/b50fc6f2cd40729302e8a8c863e13729#file-console_debug-log
3.43 KB
MikkelD 01/09/2023 09:37 PM
Thanks. That is really helpful. Now we just have to wait until I get the device.
MikkelD 01/09/2023 09:49 PM
I think I found something
MikkelD 01/09/2023 09:52 PM
1
Unlike the Arduino lib, we were not waiting on the MTU exchange to finish before we declared the device connected. So that would result in the service discovery to possibly fail. You could try adding a
sleep --ms=500discover_services1z3ugma 01/10/2023 12:34 AM
1
!!! that works!
[jaguar] INFO: program 73549571-68fd-594e-80c7-a2904b16810e started
#[0x01, 0xc6, 0xd1, 0x08, 0xef, 0x8a, 0x4d]
[an instance with class-id 48]
[an instance with class-id 45]
[jaguar] INFO: program 73549571-68fd-594e-80c7-a2904b16810e stopped1z3ugma 01/10/2023 12:35 AM
neat. now onto the nitty gritty of BLE, writing and receiving the data from the device. thanks both of you for your help so far
z3ugma 01/10/2023 02:25 AM
what's the difference between
wait_for_notification subscribez3ugma 01/10/2023 03:23 AM
The way this O2Ring works is that you write a command string to '8b00ace7-eb0b-49b0-bbe9-9aee0a26e1a3', such as
This gives the command to the ring to Notify/Indicate to us when the value of the ring next changes.
b'\xaa\x17\xe8\x00\x00\x00\x00\x1b'This gives the command to the ring to Notify/Indicate to us when the value of the ring next changes.
b'aa17e8000000001b'
[O2Ring 0543] Sending aa17e8000000001b
Writing b'\xaa\x17\xe8\x00\x00\x00\x00\x1b' up to 20 b'\xaa\x17\xe8\x00\x00\x00\x00\x1b'
[O2Ring 0543] Characteristic 8b00ace7-eb0b-49b0-bbe9-9aee0a26e1a3 write value performed
[O2Ring 0543] Characteristic 0734594a-a8e7-4b1a-a6b1-cd5243059a57 updated: 5500ff00000d0061320000000000340000120100
o2pkt recv: 5500ff00000d0061320000000000340000120100
want 21 have 20
[O2Ring 0543] Need more data
[O2Ring 0543] Characteristic 0734594a-a8e7-4b1a-a6b1-cd5243059a57 updated: 07
o2pkt recv: 07
[O2Ring 0543] Final recv: 5500ff00000d006132000000000034000012010007
[O2Ring 0543] 61320000000000340000120100
[O2Ring 0543] SpO2 97%, HR 50 bpm, Perfusion Idx 18, motion 0, batt 52%MikkelD 01/10/2023 12:16 PM
It is common to have the while loop in a task to have it run interleaved:
characteristics.subscribe // This will subscribe to notifications on the characteristic. The call returns immediately
while true:
notification := characteristics.wait_for_notification // This call blocks until a notification is received. The notification is a ByteArray
print "I received a notification: $notification"It is common to have the while loop in a task to have it run interleaved:
characteristics.subscribe
task::
while true:
notification := characteristics.wait_for_notificationMikkelD 01/10/2023 12:16 PM
If you no longer wish to received notifications, call
unsubscribez3ugma 01/14/2023 06:37 PM@MikkelD did you receive your ring? XD
z3ugma 01/14/2023 06:38 PM
I’m going to spend some of today getting the write/notify loop working. I send a “command packet” to the write characteristic every second, and receive ~127 bytes back from the notify characteristic subscription
z3ugma 01/15/2023 02:45 PM
Got it working pretty well. Sometimes the ring does not play nicely, especially when you go out of range.
Is there a way to
Is there a way to
wait_for_notificationwhile true:
write_characteristic.write #[0xaa, 0x1b, 0xe4, 0x00, 0x00, 0x01, 0x00, 0x00, 0x5e] // Realtime
first_block := subscribe_characteristic.wait_for_notification //Get first packet
msg_length := first_block[5]
total_length := msg_length + 8
print "$total_length @ $Time.now.utc"
print (hex.encode first_block)
//You'll get 20 bytes at a time
(total_length / 20 ).to_float.floor.to_int.repeat:
notificationline := subscribe_characteristic.wait_for_notification
print (hex.encode notificationline)
sleep --ms=800z3ugma 01/15/2023 02:58 PM
^^ here is how the method is implemented in https://github.com/toitlang/toit/blob/master/lib/ble.toit
Maybe I could extend the class RemoteCharacteristic with another method, wait_for_notification_with_timeout that accepts a timeout parameter and only loops for that many ms
/**
Waits until the remote device sends a notification or indication on the characteristics. Returns the
notified/indicated value.
See $subscribe.
*/
wait_for_notification -> ByteArray?:
if properties & (CHARACTERISTIC_PROPERTY_INDICATE | CHARACTERISTIC_PROPERTY_NOTIFY) == 0:
throw "Characteristic does not support notifications or indications"
while true:
resource_state_.clear_state VALUE_DATA_READY_EVENT_
buf := ble_get_value_ resource_
if buf: return buf
state := resource_state_.wait_for_state VALUE_DATA_READY_EVENT_ | VALUE_DATA_READ_FAILED_EVENT_ | DISCONNECTED_EVENT_
if state & VALUE_DATA_READ_FAILED_EVENT_ != 0: throw_error_
if state & DISCONNECTED_EVENT_ != 0: throw "Disconnected"^^ here is how the method is implemented in https://github.com/toitlang/toit/blob/master/lib/ble.toit
Maybe I could extend the class RemoteCharacteristic with another method, wait_for_notification_with_timeout that accepts a timeout parameter and only loops for that many ms
MikkelD 01/15/2023 09:06 PM
Hey. Yes I got the ring, but this week has been crazy. Will unpack it tomorrow evening and get the pr done
MikkelD 01/15/2023 09:08 PM
Normally timeout are done like this:
That said, I think the BLE library needs to be more aware of disconnects. I am still thinking about how to implement that properly.
with_timeout --ms=4000:
data := char.wait_for_notificationThat said, I think the BLE library needs to be more aware of disconnects. I am still thinking about how to implement that properly.
MikkelD 01/16/2023 07:49 PM@z3ugma I have the o2ring working without the sleep now. 
1
1z3ugma 01/16/2023 08:18 PM
Great news
bitphlipphar 01/18/2023 08:38 PM@z3ugma : Jaguar v1.8.6 is out with 3 fixes from @MikkelD 1
172 messages in total