add INA219 Bidirectional Current/Power Monitor

Author: shaoziyang

sensor/INA219/README.md

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+# INA219  
+
+Zerø-Drift, Bidirectional Current/Power Monitor With I2C Interface.
+
+![](ina219.jpg)
+
+
+
+## description
+
+Calibration Register must be written in order to read the current value. Default Calibration Register value is 4096, which has a significant error and needs to be calibrated according to the actual circuit.
+
+
+## uasge
+
+```
+from machine import Pin, SoftI2C
+import ina219
+
+# please modify scl/sda to the actual pins.
+i2c = SoftI2C(scl=Pin(pins.pin_SCL), sda=Pin(pins.pin_SDA))
+
+ina = ina219.INA219(i2c)
+ina.calreg(3450)
+
+v = ina.volt()
+c = ina.current()
+p = ina.power()
+
+```
+
+From microbit/micropython Chinese community.  
+www.micropython.org.cn

sensor/INA219/ina219.jpg

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+'''
+    mpy drive for INA219 Bidirectional Current/Power Monitor
+
+    Author: shaoziyang
+    Date:   2024.5
+
+    http://www.micropython.org.cn
+
+'''
+from micropython import const
+
+INA219_ADDR = const(64)
+
+class INA219():
+    def __init__(self, i2c):
+        self.i2c = i2c
+        self.rb = bytearray(2)
+        self.tb = bytearray(2)
+        self.setreg(0, 0x8000)  # reset
+        self.setreg(0, 0x3fff)
+        self.calreg(4096)       # default Calibration Register
+
+    def setreg(self, reg, dat):
+        self.tb[0] = dat//256
+        self.tb[1] = dat
+        self.i2c.writeto_mem(INA219_ADDR, reg, self.tb)
+
+    def getreg(self, reg):
+        self.i2c.readfrom_mem_into(INA219_ADDR, reg, self.rb)
+        return self.rb[0]*256+self.rb[1]
+
+    def calreg(self, value=None):
+        if value == None:
+            return self.getreg(5)
+        else:
+            self.setreg(5, value)
+
+    def volt(self):
+        return self.getreg(2)/2000
+    
+    def current(self):
+        return self.getreg(4)/10000
+
+    def power(self):
+        return self.getreg(3)/500
+