powertest

powertest.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+from smbus2 import SMBus
+from time import sleep
+
+ADDRESS = 0x40
+CURRENT_LSB = 0.00032
+VBUS_LSB = 0.00125
+SHUNT_LSB = 0.0000025
+
+class Data:
+    current = 0.0
+    voltage = 0.0
+    voltageCorrected = 0.0
+    power = 0.0
+    powerCorrected = 0.0
+
+
+def readReg(bus, reg):
+    regWord = bus.read_word_data(ADDRESS, reg) & 0xFFFF
+    regValue = ((regWord << 8) & 0xFF00) + (regWord >> 8)
+    #print(f'{bin(regWord)}\t{bin(regValue)}')
+    return regValue
+
+def writeReg(bus, reg, val):
+    regBytes = [(val >> 8) & 0xFF,val & 0xFF]
+    print(regBytes)
+    bus.write_i2c_block_data(ADDRESS, reg, regBytes)
+
+def getData(bus):
+    powerData.current = float(readReg(bus, 0x04)) * CURRENT_LSB
+    powerData.voltage = float(readReg(bus, 0x02)) * VBUS_LSB
+    powerData.voltageCorrected = powerData.voltage / 1.04982
+    powerData.power = float(readReg(bus, 0x03)) * CURRENT_LSB * 25.0
+    powerData.powerCorrected = powerData.current * powerData.voltageCorrected
+
+with SMBus(1) as bus:
+    powerData = Data()
+    # program calibration register
+    # calibration for double pink: 0x0b60
+    # cal for pink/blue: 0x08b6
+    writeReg(bus, 0x05, 0x08b6)
+    sleep(2)
+    while True:
+        print("\033c")
+        getData(bus)
+        #print(f"Vshunt:\t\t{float(readReg(bus, 0x01))*SHUNT_LSB} V")
+        print(f"Vbus:\t\t{powerData.voltage} V")
+        #print(f"VbusC:\t\t{powerData.voltageCorrected} V")
+        print(f"Current:\t{powerData.current} A")
+        print(f"Power:\t\t{powerData.power} W")
+        #print(f"PowerC:\t\t{powerData.powerCorrected} W")
+        #print(bus.read_word_data(ADDRESS, 0x00))
+        print()
+        sleep(1)
+
+# Calibration Calculations
+# Max of 10A (for solar panel out)
+# Current_LSB = 10A / 2^15 = 3.0517... uA/bit
+# go with 320 uA/bit = 0.32 mA/bit
+# 
+# Shunt resistor value
+# R_shunt = 5 mOhms = 0.005 Ohms
+#
+# Calibration Register
+# CAL = 0.00512 / (Current_LSB * R_shunt) = 0.00512 / (.00032 * .005) = 3200
+# CAL = 0x0C80
+