improve the speed of storage syncs via BLE

[TuEmb]

No description provided.

[gemini-code-assist]

Code Review

This pull request aims to increase the speed of storage syncs over BLE by reducing the connection interval and removing a sleep in the data transfer loop. While these changes will likely improve throughput, they also introduce potential issues with power consumption and connection stability. My review includes two main points:

1. The new fixed, short connection interval is aggressive and may not be supported by all central devices, and will increase power draw. I've suggested using a range to provide more flexibility.
2. Removing the k_msleep can lead to a busy-wait loop when BLE buffers are full, which will also consume excessive power. I've recommended switching to a more efficient event-driven approach using callbacks and semaphores.

Addressing these points will help ensure the performance improvements don't come at the cost of significantly reduced battery life or connection reliability.

[gemini-code-assist]

Reducing the connection interval to 7.5ms will significantly increase data throughput, but it will also substantially increase power consumption. Furthermore, requesting a fixed and very short connection interval might cause issues with some central devices (e.g., smartphones) that may not be able to sustain such a fast interval, potentially leading to connection instability. Consider using a slightly larger range for MIN and MAX intervals to give the central device more flexibility.

CONFIG_BT_PERIPHERAL_PREF_MIN_INT=6
# 15ms
CONFIG_BT_PERIPHERAL_PREF_MAX_INT=12

[gemini-code-assist]

By removing k_msleep(100), this loop can become a busy-wait loop if the BLE transmit buffers fill up. When bt_gatt_notify() in write_to_gatt() returns an error indicating it cannot accept more data, this loop will spin very quickly, consuming significant CPU resources and power, even with k_yield(). This could negatively impact battery life.

A more power-efficient approach would be to use an event-driven mechanism. For instance, you could use bt_gatt_notify_cb() with a callback that signals a semaphore when the transmission is complete, allowing this thread to sleep until it's possible to send more data.