class DHT11_PIO:
def __init__(self, data_pin):
pin = Pin(data_pin, Pin.IN, Pin.PULL_UP)
self.sm = StateMachine(0)
self.sm.init(DHT11, freq=500000, set_base=pin, in_base=pin)
self.start = SmAddr(0)
def read(self):
# Reset the state machine to start a fresh transaction
SmRestart(0)
SmExec(0, self.start)
# Activate the state machine and then sleep until it should be complete
self.sm.active(1)
utime.sleep_ms(20)
self.sm.active(0)
# Exception if the amount of data is wrong
if SmRxLevel(0) != 2:
while SmRxLevel(0):
self.sm.get()
raise Timeout()
# Read back the data from the Rx FIFO as
data = self.sm.get()
data = (data << 20) + self.sm.get()
# Calculate and check checksum
if (sum(data >> i * 8 for i in range(1, 5)) - data) & 255:
raise BadChecksum()
return self.decode(data)
def decode(self, data):
humidity = (data >> 32
) & 255 #DHT11 provides integer humidity (no decimal part)
temperature = (
data >> 16
) & 255 #DHT11 provides signed integer temperature (no decimal part)
return humidity, temperature
# Function for core1 to execute to write to the given UART.
def core1_task(uart, text):
uart.write(text)
# Set up the hard UART we're going to use to print characters.
uart = UART(1, UART_BAUD, tx=HARD_UART_TX_PIN)
for pio_prog in ("uart_rx_mini", "uart_rx"):
# Set up the state machine we're going to use to receive the characters.
sm = StateMachine(
0,
globals()[pio_prog],
freq=8 * UART_BAUD,
in_base=PIO_RX_PIN, # For WAIT, IN
jmp_pin=PIO_RX_PIN, # For JMP
)
sm.irq(handler)
sm.active(1)
# Tell core 1 to print some text to UART 1
text = "Hello, world from PIO, using {}!".format(pio_prog)
_thread.start_new_thread(core1_task, (uart, text))
# Echo characters received from PIO to the console.
for i in range(len(text)):
print(chr(sm.get() >> 24), end="")
print()