build

boards/default/micropython/build/lib/hx720.py

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+"""
+HX720/HX711
+
+Micropython	library for the HX720/HX711(Load Cell)
+=======================================================
+@dahanzimin From the Mixly Team
+"""
+import time
+from machine import Pin
+from micropython import const
+
+DATA_BITS 			= const(24)
+READY_TIMEOUT_SEC 	= const(500)
+
+class HX720:
+	def __init__(self, sck_pin, dat_pin, scale=500, pulse_obj=1):
+		self._sck = Pin(sck_pin, Pin.OUT, value=0)
+		self._dat = Pin(dat_pin, Pin.IN, Pin.PULL_UP)
+		self._obj = min(max(pulse_obj, 1), 3)
+		self.scale = scale
+		self.tare()
+
+	def _wait(self):
+		"""超时响应报错"""
+		star = time.ticks_ms()
+		while not self.is_ready():
+			if time.ticks_diff(time.ticks_ms(), star) > READY_TIMEOUT_SEC:
+				raise AttributeError("Cannot find a HX711/HX720")
+
+	def is_ready(self):
+		"""检查是否有数据可以读取"""
+		return self._dat.value() == 0
+
+	def set_scale(self, scale):
+		"""设置比例因子"""
+		self.scale = scale
+
+	def read_raw(self):
+		"""读取传感器的原始数据"""
+		if not self.is_ready():
+			self._wait()        
+		raw_data = 0
+		for _ in range(DATA_BITS):
+			self._sck.value(1)
+			self._sck.value(0)
+			raw_data = raw_data << 1 | self._dat.value()
+
+		# 根据脉冲功能设置多读几次
+		for _ in range(self._obj):
+			self._sck.value(1)
+			self._sck.value(0)
+		
+		return raw_data | 0xFF000000 if raw_data & 0x800000 else raw_data
+
+	def tare(self, times=10):
+		"""清零传感器"""
+		total = 0
+		for _ in range(times):
+			total += self.read_raw()
+		self.offset = total / times
+
+	def read_weight(self, times=5):
+		"""读取重量数据，返回去掉偏移量的平均值"""
+		total = 0
+		for _ in range(times):
+			total += self.read_raw()
+		return round((total / times - self.offset) / self.scale, 2)