3 ms·

> I use a Logitech mouse which can connect wirelessly to a USB dongle over RF, providing lower latency and better battery life than Bluetooth In my experience

> I use a Logitech mouse which can connect wirelessly to a USB dongle over RF, providing lower latency and better battery life than Bluetooth In my experience this has not been true at all now that most Logitech mice use LE ("Bluetooth Smart") rather than BT. The only advantage the RF dongle has is that it works without an OS.... or on an OS without a BT/LE stack, like here.

jwells89 2y ago
Dongles can also be handy for peripherals that are frequently used on different machines, particularly if they don't have built-in multi-pairing and quick host switching. One exception to the "no BT/LE stack" case is the combo of Apple input devices paired with Macs or hackintoshed generic PCs with a handful of Broadcom-based BT chipsets used by Macs. macOS flips some bit on those cards that tells them to keep Apple peripherals paired at all times, which allows you to type and mouse around in the pre-boot environment and subsequently-booted OSes without drivers even on old BIOS-based machines which can't load EFI drivers.
- felixg3 2y ago
  It’s an apple exclusive thing, as they seem to be the only implementer of a USB Bluetooth HID bridge which the Broadcom adapter essentially exposes in firmware. There are a few Bluetooth dongles with CSR chips that can be turned into USB HID interfaces with previously paired Bluetooth peripherals.
- AshamedCaptain 2y ago
  It just remembers any peripherals you have already paired with the controller, it's nothing specific to "Apple peripherals". And on the next boot it then shows up as a USB HID device in the pre-OS environment, talking Bluetooth behind the scenes to those same peripherals. I have a (10 year old?) DBT-120 from D-Link which did this, and even Windows had some support for it. Never seen anything for BLE; my wild guess is that Apple now simply puts a BT stack on their UEFI. Not too far-fetched. But it doesn't really help the noOS use case, since you still need a BT stack with UI _somewhere_ in order to pair your keyboard for the first time.
5ADBEEF 2y ago
RF dongles almost always are Nordic Semiconductor parts and they use their proprietary (but open) protocol called Enhanced Shockburst. The minimum latency of BLE is 7.5ms (fastest connection interval in the spec) while ESB can be in the 100s of microseconds. Not sure about power savings but latency is better.
- AshamedCaptain 2y ago
  > RF dongles almost always are Nordic Semiconductor parts and they use their proprietary (but open) protocol called Enhanced Shockburst. Not really, Logitech actually uses the LE PHY even for their "RF" protocol, at least since the Logitech Bolt controller which is what TFA is talking about. You can sniff Bolt traffic with a LE sniffer. > The minimum latency of BLE is 7.5ms (fastest connection interval in the spec) while ESB can be in the 100s of microseconds This makes for an average 4ms of latency, which matches what Logitech advertises. Then USB is then going to introduce 5-10ms at the very least...

jwells89 2y ago

Dongles can also be handy for peripherals that are frequently used on different machines, particularly if they don't have built-in multi-pairing and quick host switching. One exception to the "no BT/LE stack" case is the combo of Apple input devices paired with Macs or hackintoshed generic PCs with a handful of Broadcom-based BT chipsets used by Macs. macOS flips some bit on those cards that tells them to keep Apple peripherals paired at all times, which allows you to type and mouse around in the pre-boot environment and subsequently-booted OSes without drivers even on old BIOS-based machines which can't load EFI drivers.

felixg3 2y ago
It’s an apple exclusive thing, as they seem to be the only implementer of a USB Bluetooth HID bridge which the Broadcom adapter essentially exposes in firmware. There are a few Bluetooth dongles with CSR chips that can be turned into USB HID interfaces with previously paired Bluetooth peripherals.
AshamedCaptain 2y ago
It just remembers any peripherals you have already paired with the controller, it's nothing specific to "Apple peripherals". And on the next boot it then shows up as a USB HID device in the pre-OS environment, talking Bluetooth behind the scenes to those same peripherals. I have a (10 year old?) DBT-120 from D-Link which did this, and even Windows had some support for it. Never seen anything for BLE; my wild guess is that Apple now simply puts a BT stack on their UEFI. Not too far-fetched. But it doesn't really help the noOS use case, since you still need a BT stack with UI _somewhere_ in order to pair your keyboard for the first time.

5ADBEEF 2y ago

RF dongles almost always are Nordic Semiconductor parts and they use their proprietary (but open) protocol called Enhanced Shockburst. The minimum latency of BLE is 7.5ms (fastest connection interval in the spec) while ESB can be in the 100s of microseconds. Not sure about power savings but latency is better.

AshamedCaptain 2y ago
> RF dongles almost always are Nordic Semiconductor parts and they use their proprietary (but open) protocol called Enhanced Shockburst. Not really, Logitech actually uses the LE PHY even for their "RF" protocol, at least since the Logitech Bolt controller which is what TFA is talking about. You can sniff Bolt traffic with a LE sniffer. > The minimum latency of BLE is 7.5ms (fastest connection interval in the spec) while ESB can be in the 100s of microseconds This makes for an average 4ms of latency, which matches what Logitech advertises. Then USB is then going to introduce 5-10ms at the very least...