examples/bluetooth: Add basic BLE peripheral examples.

Consisting of:
- ble_advertising.py -- helper to generate advertising payload.
- ble_temperature.py -- simple temperature device.
- ble_uart_periperhal.py -- BLE UART wrapper.
- ble_uart_repl.py -- dupterm-compatible uart.

1 files changed, 80 insertions, 0 deletions

diff --git a/examples/bluetooth/ble_uart_repl.py b/examples/bluetooth/ble_uart_repl.py
new file mode 100644
index 000000000..430a571a6
--- /dev/null
+++ b/examples/bluetooth/ble_uart_repl.py
@@ -0,0 +1,80 @@
+# Proof-of-concept of a REPL over BLE UART.
+#
+# Tested with the Adafruit Bluefruit app on Android.
+# Set the EoL characters to \r\n.
+
+import bluetooth
+import io
+import os
+import micropython
+import machine
+
+from ble_uart_peripheral import BLEUART
+
+_MP_STREAM_POLL = const(3)
+_MP_STREAM_POLL_RD = const(0x0001)
+
+# TODO: Remove this when STM32 gets machine.Timer.
+if hasattr(machine, 'Timer'):
+    _timer = machine.Timer(-1)
+else:
+    _timer = None
+
+# Batch writes into 50ms intervals.
+def schedule_in(handler, delay_ms):
+    def _wrap(_arg):
+        handler()
+    if _timer:
+        _timer.init(mode=machine.Timer.ONE_SHOT, period=delay_ms, callback=_wrap)
+    else:
+        micropython.schedule(_wrap, None)
+
+# Simple buffering stream to support the dupterm requirements.
+class BLEUARTStream(io.IOBase):
+    def __init__(self, uart):
+        self._uart = uart
+        self._tx_buf = bytearray()
+        self._uart.irq(self._on_rx)
+
+    def _on_rx(self):
+        # Needed for ESP32.
+        if hasattr(os, 'dupterm_notify'):
+            os.dupterm_notify(None)
+
+    def read(self, sz=None):
+        return self._uart.read(sz)
+
+    def readinto(self, buf):
+        avail = self._uart.read(len(buf))
+        if not avail:
+            return None
+        for i in range(len(avail)):
+            buf[i] = avail[i]
+        return len(avail)
+
+    def ioctl(self, op, arg):
+        if op == _MP_STREAM_POLL:
+            if self._uart.any():
+                return _MP_STREAM_POLL_RD
+        return 0
+
+    def _flush(self):
+        data = self._tx_buf[0:100]
+        self._tx_buf = self._tx_buf[100:]
+        self._uart.write(data)
+        if self._tx_buf:
+            schedule_in(self._flush, 50)
+
+    def write(self, buf):
+        empty = not self._tx_buf
+        self._tx_buf += buf
+        if empty:
+            schedule_in(self._flush, 50)
+
+
+def start():
+    ble = bluetooth.BLE()
+    uart = BLEUART(ble, name='mpy-repl')
+    stream = BLEUARTStream(uart)
+
+    os.dupterm(stream)