add toggle button for USB and improve BLE polling rate

README.md

@@ -14,6 +14,7 @@ over BLE using HID over GATT Profile.
 You will need the following hardware to make the device:
 - Raspberry Pi Pico W
 - USB extension cable
+- (Optional) Momentary push button
 
 ![Wiring schematic](schematic.svg)
 
@@ -35,8 +36,10 @@ and the green cable to TP3.
 
 ![Wiring of USB connectors to Raspberry Pi Pico W](diagram.png)
 
+Optionally, a momentary push button can be wired to GP5 and GND to switch between Bluetooth and USB passthrough mode.
+
 The individual wires on the USB can be fragile, so hot glue or other strain
-relief is a good idea. 
+relief is a good idea.
 
 ### Software
 
@@ -64,6 +67,11 @@ with many LEDs, the sudden power draw when plugging in can cause issues, so it
 is recommended to turn off the LEDs before connecting to the Raspberry Pi Pico
 W.
 
+If you connected a push button to GP5, then pressing the button will switch
+between Bluetooth connection mode and USB passthrough mode. In USB passthrough
+mode, the inputs will be passed through from the host to the USB connection made
+through the test points or the Micro USB port.
+
 In principle, the Pico BLE HID will work with peripherals plugged into
 a USB hub, but compatibility will vary with the specific hardware used,
 including the peripherals, USB hub, and operating system. This is because the