# 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 # was 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):		# SPI data transfer main routine. 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 xrange(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 xrange(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 xrange(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 xrange(0x44):		
		res = -1
		v = xfr1(0,x,0)
		print '@',format(x,'02X'),
		print '	','	$',format(v,'02X')			
			
			
def GetOpMode():
	x = xfr1(0,1,0)	# register 1 controls the RFM IC mode. eg FSK/LORA/SLEEP/STANDBY/TX/RX
	return x
				
def GetRegBitRate():
	h = xfr1(0,2,0)
	l = xfr1(0,3,0)
	return h*256 + l

def GetCarrierFreq():
	h = readReg(6)	# MSB
	m = readReg(7)
	l = readReg(8)	# LSB
	return ((h*256.0+m)*256.0 + l)*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 = r-256*m
	writeReg(6,h)	# MSB
	writeReg(7,m)
	writeReg(8,l)	# 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()