micropython/drivers: Move "nrf24l01" radio driver from main repo.

Signed-off-by: Jim Mussared <[email protected]>

Author: jimmo

micropython/drivers/radio/nrf24l01/manifest.py

@@ -0,0 +1 @@
+module("nrf24l01.py", opt=3)

micropython/drivers/radio/nrf24l01/nrf24l01.py

@@ -0,0 +1,252 @@
+"""NRF24L01 driver for MicroPython
+"""
+
+from micropython import const
+import utime
+
+# nRF24L01+ registers
+CONFIG = const(0x00)
+EN_RXADDR = const(0x02)
+SETUP_AW = const(0x03)
+SETUP_RETR = const(0x04)
+RF_CH = const(0x05)
+RF_SETUP = const(0x06)
+STATUS = const(0x07)
+RX_ADDR_P0 = const(0x0A)
+TX_ADDR = const(0x10)
+RX_PW_P0 = const(0x11)
+FIFO_STATUS = const(0x17)
+DYNPD = const(0x1C)
+
+# CONFIG register
+EN_CRC = const(0x08)  # enable CRC
+CRCO = const(0x04)  # CRC encoding scheme; 0=1 byte, 1=2 bytes
+PWR_UP = const(0x02)  # 1=power up, 0=power down
+PRIM_RX = const(0x01)  # RX/TX control; 0=PTX, 1=PRX
+
+# RF_SETUP register
+POWER_0 = const(0x00)  # -18 dBm
+POWER_1 = const(0x02)  # -12 dBm
+POWER_2 = const(0x04)  # -6 dBm
+POWER_3 = const(0x06)  # 0 dBm
+SPEED_1M = const(0x00)
+SPEED_2M = const(0x08)
+SPEED_250K = const(0x20)
+
+# STATUS register
+RX_DR = const(0x40)  # RX data ready; write 1 to clear
+TX_DS = const(0x20)  # TX data sent; write 1 to clear
+MAX_RT = const(0x10)  # max retransmits reached; write 1 to clear
+
+# FIFO_STATUS register
+RX_EMPTY = const(0x01)  # 1 if RX FIFO is empty
+
+# constants for instructions
+R_RX_PL_WID = const(0x60)  # read RX payload width
+R_RX_PAYLOAD = const(0x61)  # read RX payload
+W_TX_PAYLOAD = const(0xA0)  # write TX payload
+FLUSH_TX = const(0xE1)  # flush TX FIFO
+FLUSH_RX = const(0xE2)  # flush RX FIFO
+NOP = const(0xFF)  # use to read STATUS register
+
+
+class NRF24L01:
+    def __init__(self, spi, cs, ce, channel=46, payload_size=16):
+        assert payload_size <= 32
+
+        self.buf = bytearray(1)
+
+        # store the pins
+        self.spi = spi
+        self.cs = cs
+        self.ce = ce
+
+        # init the SPI bus and pins
+        self.init_spi(4000000)
+
+        # reset everything
+        ce.init(ce.OUT, value=0)
+        cs.init(cs.OUT, value=1)
+
+        self.payload_size = payload_size
+        self.pipe0_read_addr = None
+        utime.sleep_ms(5)
+
+        # set address width to 5 bytes and check for device present
+        self.reg_write(SETUP_AW, 0b11)
+        if self.reg_read(SETUP_AW) != 0b11:
+            raise OSError("nRF24L01+ Hardware not responding")
+
+        # disable dynamic payloads
+        self.reg_write(DYNPD, 0)
+
+        # auto retransmit delay: 1750us
+        # auto retransmit count: 8
+        self.reg_write(SETUP_RETR, (6 << 4) | 8)
+
+        # set rf power and speed
+        self.set_power_speed(POWER_3, SPEED_250K)  # Best for point to point links
+
+        # init CRC
+        self.set_crc(2)
+
+        # clear status flags
+        self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)
+
+        # set channel
+        self.set_channel(channel)
+
+        # flush buffers
+        self.flush_rx()
+        self.flush_tx()
+
+    def init_spi(self, baudrate):
+        try:
+            master = self.spi.MASTER
+        except AttributeError:
+            self.spi.init(baudrate=baudrate, polarity=0, phase=0)
+        else:
+            self.spi.init(master, baudrate=baudrate, polarity=0, phase=0)
+
+    def reg_read(self, reg):
+        self.cs(0)
+        self.spi.readinto(self.buf, reg)
+        self.spi.readinto(self.buf)
+        self.cs(1)
+        return self.buf[0]
+
+    def reg_write_bytes(self, reg, buf):
+        self.cs(0)
+        self.spi.readinto(self.buf, 0x20 | reg)
+        self.spi.write(buf)
+        self.cs(1)
+        return self.buf[0]
+
+    def reg_write(self, reg, value):
+        self.cs(0)
+        self.spi.readinto(self.buf, 0x20 | reg)
+        ret = self.buf[0]
+        self.spi.readinto(self.buf, value)
+        self.cs(1)
+        return ret
+
+    def flush_rx(self):
+        self.cs(0)
+        self.spi.readinto(self.buf, FLUSH_RX)
+        self.cs(1)
+
+    def flush_tx(self):
+        self.cs(0)
+        self.spi.readinto(self.buf, FLUSH_TX)
+        self.cs(1)
+
+    # power is one of POWER_x defines; speed is one of SPEED_x defines
+    def set_power_speed(self, power, speed):
+        setup = self.reg_read(RF_SETUP) & 0b11010001
+        self.reg_write(RF_SETUP, setup | power | speed)
+
+    # length in bytes: 0, 1 or 2
+    def set_crc(self, length):
+        config = self.reg_read(CONFIG) & ~(CRCO | EN_CRC)
+        if length == 0:
+            pass
+        elif length == 1:
+            config |= EN_CRC
+        else:
+            config |= EN_CRC | CRCO
+        self.reg_write(CONFIG, config)
+
+    def set_channel(self, channel):
+        self.reg_write(RF_CH, min(channel, 125))
+
+    # address should be a bytes object 5 bytes long
+    def open_tx_pipe(self, address):
+        assert len(address) == 5
+        self.reg_write_bytes(RX_ADDR_P0, address)
+        self.reg_write_bytes(TX_ADDR, address)
+        self.reg_write(RX_PW_P0, self.payload_size)
+
+    # address should be a bytes object 5 bytes long
+    # pipe 0 and 1 have 5 byte address
+    # pipes 2-5 use same 4 most-significant bytes as pipe 1, plus 1 extra byte
+    def open_rx_pipe(self, pipe_id, address):
+        assert len(address) == 5
+        assert 0 <= pipe_id <= 5
+        if pipe_id == 0:
+            self.pipe0_read_addr = address
+        if pipe_id < 2:
+            self.reg_write_bytes(RX_ADDR_P0 + pipe_id, address)
+        else:
+            self.reg_write(RX_ADDR_P0 + pipe_id, address[0])
+        self.reg_write(RX_PW_P0 + pipe_id, self.payload_size)
+        self.reg_write(EN_RXADDR, self.reg_read(EN_RXADDR) | (1 << pipe_id))
+
+    def start_listening(self):
+        self.reg_write(CONFIG, self.reg_read(CONFIG) | PWR_UP | PRIM_RX)
+        self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)
+
+        if self.pipe0_read_addr is not None:
+            self.reg_write_bytes(RX_ADDR_P0, self.pipe0_read_addr)
+
+        self.flush_rx()
+        self.flush_tx()
+        self.ce(1)
+        utime.sleep_us(130)
+
+    def stop_listening(self):
+        self.ce(0)
+        self.flush_tx()
+        self.flush_rx()
+
+    # returns True if any data available to recv
+    def any(self):
+        return not bool(self.reg_read(FIFO_STATUS) & RX_EMPTY)
+
+    def recv(self):
+        # get the data
+        self.cs(0)
+        self.spi.readinto(self.buf, R_RX_PAYLOAD)
+        buf = self.spi.read(self.payload_size)
+        self.cs(1)
+        # clear RX ready flag
+        self.reg_write(STATUS, RX_DR)
+
+        return buf
+
+    # blocking wait for tx complete
+    def send(self, buf, timeout=500):
+        self.send_start(buf)
+        start = utime.ticks_ms()
+        result = None
+        while result is None and utime.ticks_diff(utime.ticks_ms(), start) < timeout:
+            result = self.send_done()  # 1 == success, 2 == fail
+        if result == 2:
+            raise OSError("send failed")
+
+    # non-blocking tx
+    def send_start(self, buf):
+        # power up
+        self.reg_write(CONFIG, (self.reg_read(CONFIG) | PWR_UP) & ~PRIM_RX)
+        utime.sleep_us(150)
+        # send the data
+        self.cs(0)
+        self.spi.readinto(self.buf, W_TX_PAYLOAD)
+        self.spi.write(buf)
+        if len(buf) < self.payload_size:
+            self.spi.write(b"\x00" * (self.payload_size - len(buf)))  # pad out data
+        self.cs(1)
+
+        # enable the chip so it can send the data
+        self.ce(1)
+        utime.sleep_us(15)  # needs to be >10us
+        self.ce(0)
+
+    # returns None if send still in progress, 1 for success, 2 for fail
+    def send_done(self):
+        if not (self.reg_read(STATUS) & (TX_DS | MAX_RT)):
+            return None  # tx not finished
+
+        # either finished or failed: get and clear status flags, power down
+        status = self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)
+        self.reg_write(CONFIG, self.reg_read(CONFIG) & ~PWR_UP)
+        return 1 if status & TX_DS else 2