#!/usr/bin/python

import spidev
import time
import RPi.GPIO as GPIO
from decimal import *

tnom = 25
rnom = 10000.0
corr = 4800
temp_gpio = { 
        0: {
            "BCM": 20,
            "Rk": 9770.0 #9770,
        },
        1: {
            "BCM": 26,
            "Rk": 10000.0
            } 
        }

GPIO.setmode(GPIO.BCM)
for k in temp_gpio:
    GPIO.setup(temp_gpio[k]["BCM"], GPIO.OUT)
    GPIO.output(temp_gpio[k]["BCM"], False)

def read_spiADC(spi, channel):
    if channel > 7 or channel < 0:
        return []
    GPIO.output(temp_gpio[channel]["BCM"], True)
    hchbit=channel >> 2
    lchbits = channel & 0x03
    to_send = [ hchbit | 0x06, lchbits << 6, 0x00 ]
    spi.cshigh=True
#    time.sleep(0.01)
    spi.cshigh = False
    r=spi.xfer(to_send)
    spi.cshigh = True
    GPIO.output(temp_gpio[channel]["BCM"], False)
#    time.sleep(0.01)
    highbyte = r[1]
    lowbyte = r[2]
    value = (highbyte << 8) | lowbyte
    return value

def calc_temp(adc_reading, channel = 0):
    rser = temp_gpio[channel]["Rk"]
    r = (rser/(4095/adc_reading - 1))
    r = r - corr
    t = r/rnom
    if t < 0:
        t = t * -1
    t = float(Decimal(t).ln()) / 4050 + 1.0/(tnom + 273.15)
    t = 1/t
    t = t - 273.15
    return t

#GPIO.output(temp_gpio[1], True)
#while True:
#    pass

spi = spidev.SpiDev()

spi.open(0,0)
spi.mode = 0
spi.max_speed_hz = 1000000
while True:
    chan0 = read_spiADC(spi, 0)
    chan1 = read_spiADC(spi, 1)
    r0 = 0
    r1 = 0
    t0 = 0
    t1 = 0
    if chan0 != 0:
        r0 = rnom/(4095/ chan0 - 1)
        t0 = calc_temp(chan0, 0)
    if chan1 != 0:
        r1 = rnom/(4095/ chan1 - 1)
        t1 = calc_temp(chan1, 1)
    print("{:d} R={:d} T={:.2f} |\t| {:d} R={:d} T={:.2f}".format(chan0,int(r0), t0, chan1, int(r1), t1), end="\r")
    time.sleep(0.25)
#    print(str(chan0) +" R=" + str(int(r0)) + " T=" + str(t0) +" |\t| "+str(chan1)+" R="+str(int(r1)) + " T=" +str(t1), end="\r")

spi.close()