add si7051 high accuracy temperature sensors

Author: shaoziyang

sensor/si7051/si7051.py

@@ -0,0 +1,49 @@
+from machine import I2C
+from time import sleep_ms
+
+SI7051_I2C_ADDR = 0x40
+SI7051_CMD_HOLD_MODE = b'\xE3'
+SI7051_CMD_NO_HOLD_MODE = b'\xF3'
+SI7051_CMD_RESET = b'\xFE'
+SI7051_CMD_WRITE_USER_REG1 = b'\xE6'
+SI7051_CMD_READ_USER_REG1 = b'\xE7'
+SI7051_CMD_READ_ID1 = b'\xFA\x0F'
+SI7051_CMD_READ_ID2 = b'\xFC\xC9'
+SI7051_CMD_READ_REV = b'\x84\xB8'
+
+class si7051():
+    def __init__(self, i2c):
+        self.i2c = i2c
+
+    # get reg
+    def getReg(self, buf, n=1):
+        self.i2c.writeto(SI7051_I2C_ADDR, buf)
+        t = self.i2c.readfrom(SI7051_I2C_ADDR, n)
+        return t
+
+    def ID(self):
+        a = self.getReg(SI7051_CMD_READ_ID1, 4)
+        b = self.getReg(SI7051_CMD_READ_ID2, 4)
+        return hex(int.from_bytes(a+b,''))[2:]
+
+    def REV(self):
+        a = self.getReg(SI7051_CMD_READ_REV)
+        return a[0]
+
+    def UserReg(self, reg=''):
+        if reg == '':
+            return self.getReg(SI7051_CMD_READ_USER_REG1)[0]
+        else:
+            self.i2c.writeto(SI7051_I2C_ADDR, bytearray(SI7051_CMD_WRITE_USER_REG1) + bytearray([reg]))
+
+    def name(self):
+        a = self.getReg(SI7051_CMD_READ_ID2, 4)[0]
+        return 'si70'+str(a)
+
+    def Temperature(self, digital=2, delay=10):
+        self.i2c.writeto(SI7051_I2C_ADDR, SI7051_CMD_NO_HOLD_MODE)
+        sleep_ms(delay)
+        a = self.i2c.readfrom(SI7051_I2C_ADDR, 2)
+        b = a[0]*256 + a[1]
+        return round(b*175.72/65536 - 46.85, digital)
+