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# This example demonstrates a peripheral implementing the Nordic UART Service (NUS).
# This example demonstrates the low-level bluetooth module. For most
# applications, we recommend using the higher-level aioble library which takes
# care of all IRQ handling and connection management. See
# https://github.com/micropython/micropython-lib/tree/master/micropython/bluetooth/aioble
import bluetooth
from ble_advertising import advertising_payload
from micropython import const
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_FLAG_WRITE = const(0x0008)
_FLAG_NOTIFY = const(0x0010)
_UART_UUID = bluetooth.UUID("6E400001-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_TX = (
bluetooth.UUID("6E400003-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_NOTIFY,
)
_UART_RX = (
bluetooth.UUID("6E400002-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_WRITE,
)
_UART_SERVICE = (
_UART_UUID,
(_UART_TX, _UART_RX),
)
# org.bluetooth.characteristic.gap.appearance.xml
_ADV_APPEARANCE_GENERIC_COMPUTER = const(128)
class BLEUART:
def __init__(self, ble, name="mpy-uart", rxbuf=100):
self._ble = ble
self._ble.active(True)
self._ble.irq(self._irq)
((self._tx_handle, self._rx_handle),) = self._ble.gatts_register_services((_UART_SERVICE,))
# Increase the size of the rx buffer and enable append mode.
self._ble.gatts_set_buffer(self._rx_handle, rxbuf, True)
self._connections = set()
self._rx_buffer = bytearray()
self._handler = None
# Optionally add services=[_UART_UUID], but this is likely to make the payload too large.
self._payload = advertising_payload(name=name, appearance=_ADV_APPEARANCE_GENERIC_COMPUTER)
self._advertise()
def irq(self, handler):
self._handler = handler
def _irq(self, event, data):
# Track connections so we can send notifications.
if event == _IRQ_CENTRAL_CONNECT:
conn_handle, _, _ = data
self._connections.add(conn_handle)
elif event == _IRQ_CENTRAL_DISCONNECT:
conn_handle, _, _ = data
if conn_handle in self._connections:
self._connections.remove(conn_handle)
# Start advertising again to allow a new connection.
self._advertise()
elif event == _IRQ_GATTS_WRITE:
conn_handle, value_handle = data
if conn_handle in self._connections and value_handle == self._rx_handle:
self._rx_buffer += self._ble.gatts_read(self._rx_handle)
if self._handler:
self._handler()
def any(self):
return len(self._rx_buffer)
def read(self, sz=None):
if not sz:
sz = len(self._rx_buffer)
result = self._rx_buffer[0:sz]
self._rx_buffer = self._rx_buffer[sz:]
return result
def write(self, data):
for conn_handle in self._connections:
self._ble.gatts_notify(conn_handle, self._tx_handle, data)
def close(self):
for conn_handle in self._connections:
self._ble.gap_disconnect(conn_handle)
self._connections.clear()
def _advertise(self, interval_us=500000):
self._ble.gap_advertise(interval_us, adv_data=self._payload)
def demo():
import time
ble = bluetooth.BLE()
uart = BLEUART(ble)
def on_rx():
print("rx: ", uart.read().decode().strip())
uart.irq(handler=on_rx)
nums = [4, 8, 15, 16, 23, 42]
i = 0
try:
while True:
uart.write(str(nums[i]) + "\n")
i = (i + 1) % len(nums)
time.sleep_ms(1000)
except KeyboardInterrupt:
pass
uart.close()
if __name__ == "__main__":
demo()
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