#!/usr/bin/python3
# -*- coding: UTF-8 -*-
# https://www.adafruit.com/product/4226

import time, board, sys, os
import adafruit_ina260

sys.path.append('/home/ghz/wxlib')
import wxlib as wx
     
i2c = board.I2C()
ina260 = adafruit_ina260.INA260(i2c)

time_to_die = 0
dat_fname='solar_power'
wx_dir = "/home/ghz/solar_power_wx"

if __name__ == "__main__":
	while True:

		ts = time.strftime("%Y%m%d%H%M%S", time.gmtime())
		ina_voltage = ina260.voltage

		# 2020-10-31T072303Z: we charge the battery and flip the current measurement pi around.
		# we were originally wired to measure the down stream pi current, and the battery voltage directly.
		# with the flip we should be able to measure the current of both the down stream pi and ourselves,
		# but to keep with standard sign convention in our data, we flip the sign on the current here.
		# this will also have the effect of measuring the batt voltage from the far side of the sense resistor.
		# given the most current we've seen thru the thing so far is 4 Amps, that will lead to a max error of:
		# (V = IR) => V = 4 Amps * 0.002 Ohms = 0.008 Volts. Which i'm not going to worry about compensating for.
		dat_s = "%s\tCurrent: %.2f mA,\tVoltage: %.2f V,\tPower: %.2f mW\tPi_temp: %.2f °C\n" % \
			(ts, -ina260.current, ina_voltage, ina260.power, float(wx.pi_temp_read()) / 1000)

		wx.write_out_dat_stamp(ts, dat_fname, dat_s, wx_dir)

		if(ina_voltage <= 10.5):
			time_to_die += 1
		else:
			time_to_die = 0

		# the charge controller kills the load if the batt drops below 10.6 V
		# we however sit between the charge controller and the batt. so enforce low voltage protection ourselves
		if(time_to_die >= 4):
			os.system('/home/ghz/solar_power_wx/kill_myself')

		time.sleep(16)