# rfmtest.py - performs SPI comms on raspberry pi to RFM95 IC.	Paul Richarsd pi@sosgez.co.uk
# NB this is python2 code. SPI data transfer does not use external driver.
#
import RPi.GPIO as GPIO
from time import sleep
# define GPIO board pin assignments for comms


def swait():  # just a short delay.
    sleep(0.001)


def initports():
    global gclk, gout, gin, ginit, gen
    ginit = 15  # wassyn 3 # chip reset
    gclk = 23  # CLOCK
    gout = 19  # MOSI
    gin = 21  # MISO
    gen = 24  # chip enable (active low)
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(ginit, GPIO.OUT)
    GPIO.setup(gclk, GPIO.OUT)
    GPIO.setup(gout, GPIO.OUT)
    GPIO.setup(gen, GPIO.OUT)
    GPIO.setup(gin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    swait()
    # set default state
    GPIO.output(ginit, 0)
    GPIO.output(gclk, 0)
    GPIO.output(gout, 0)
    GPIO.output(gen, 1)
    GPIO.output(ginit, 1)
# READY FOR 1 TRANSFER


def xfr1(iswrite, address, data1):
    """Main SPI data transfer routine. A single byte is transferred out and in."""
    global gen, gout, gin, gclk
    GPIO.output(gen, 0)
    swait()
    swait()
    d1 = address & 127
    if iswrite > 0:
        d1 = d1 | 128
        swait()
        m = 128  # send MSB first
        for bit in range(8):
            if((d1 & m) > 0):
                GPIO.output(gout, 1)
            else:
                GPIO.output(gout, 0)
            swait()
            GPIO.output(gclk, 1)
            swait()
            GPIO.output(gclk, 0)
            swait()
            m = (m >> 1) & 127
        m = 128
        d2 = data1
        res = 0
        for bit in range(8):
            if((d2 & m) > 0):
                GPIO.output(gout, 1)
            else:
                GPIO.output(gout, 0)
            swait()
            res = res << 1
            GPIO.output(gclk, 1)
            if(GPIO.input(gin) > 0):
                res = res | 1
            swait()
            GPIO.output(gclk, 0)
            swait()
            m = m >> 1
        GPIO.output(gen, 1)
        swait()
        return res


def writeReg(where, data):
    xfr1(1, where, data)


def readReg(where):
    return xfr1(0, where, 0)


def ex1():  # just exercising a pin so I can see it on scope
    global gclk, gout, gin, gen, ginit
    dt = 0.01
    port = gen
    for x in range(100):
        print(1)
        GPIO.output(port, 1)
        sleep(dt)
        print(0)
        GPIO.output(port, 0)
        sleep(dt)


def readregs():
    print("Reg Value")
    for x in range(0x44):
        # res = -1
        v = xfr1(0, x, 0)
        print('@', format(x, '02X'))
        print('	', '	$', format(v, '02X'))


def GetOpMode():
    # register 1 controls the RFM IC mode. eg FSK/LORA/SLEEP/STANDBY/TX/RX
    x = xfr1(0, 1, 0)
    return x


def GetRegBitRate():
    h = xfr1(0, 2, 0)
    l_c = xfr1(0, 3, 0)
    return h * 256 + l_c


def GetCarrierFreq():
    h = readReg(6)  # MSB
    m = readReg(7)
    l_a = readReg(8)  # LSB
    return ((h * 256.0 + m) * 256.0 + l_a) * 61.035  # in Hz


def SetFreq(mhz):
    f = int(mhz * 1e6 / 61.035)
    h = int(f / 65536.0)
    r = f - h * 65536
    m = int(r / 256)
    l_b = r - 256 * m
    writeReg(6, h)  # MSB
    writeReg(7, m)
    writeReg(8, l_b)  # LSB
    return


def GetAGC():
    return xfr1(0, 0x61, 0)  # or use readReg(0x61) etc


def GetAGC1():
    return xfr1(0, 0x62, 0)


def GetAGC2():
    return xfr1(0, 0x63, 0)


def GetAGC3():
    return xfr1(0, 0x64, 0)


def ShowRegs():
    print('Some regsiter examples')
    print('Op Mode ', GetOpMode())
    print('Bit Rate ', GetRegBitRate())
    print('Default carrier freq ', GetCarrierFreq() / 1e6, 'MHz')
    print(
        'AGC regs 61-64 : ',
        format(GetAGC(), '02X'),
        format(GetAGC1(), '02X'),
        format(GetAGC2(), '02X'),
        format(GetAGC3(), '02X')
    )


def main():
    print('Simple GPIO SPI without drivers')
    sleep(0.5)  # secs
    initports()
    readregs()  # shows massive list, before any changes are made
    ShowRegs()  # shows a few interesting registers
    SetFreq(868.1)  # now write to registers 6, 7, 8
    print('New carrier freq ', GetCarrierFreq() / 1e6, ' MHz')
    print("*** Finished")
    GPIO.cleanup()


main()