Read live data from a CMS50D+ pulse oximeter with firmware v4.6

cms50dplus.py

#!/usr/bin/env python2

# Copyright (c) 2016 Tommi Airikka <tommi@airikka.net>
# License: GPLv2

import sys, struct, serial, argparse
from dateutil.parser import parse

#####################
##### Variables #####
#####################
parser = argparse.ArgumentParser(description='Download stored data from a CMS50D+ oximeter.')
parser.add_argument('device', type=str, help='path to device file')
parser.add_argument('outfile', type=str, help='output file path')
parser.add_argument('-s', '--start-time', dest='starttime', type=str, help='start time (\"YYYY-MM-DD HH:MM:SS\")')

args = parser.parse_args()

device = args.device
outfile = args.outfile
starttime = args.starttime
ser = serial.Serial()

###################
##### Helpers #####
###################
# Pack little endian
def _ple(i):
    return struct.pack("<I", i)

def _get_real_values((val1,val2)):
    
    oval1 = ord(val1)
    oval2 = ord(val2)
    v1 = oval1 - 0x80
    v2 = oval2 - 0x80
    if v1 == 0 or oval1 == 0xFF:
        v1 = 127
    if v2 == 0 or oval2 == 0xFF:
        v2 = 255
    return (v1,v2)

def _parse_list(toparse, parsed):
    print "start parsing"
    while toparse:
        if len(toparse) > 1:
            #fs = (toparse.pop(0),toparse.pop(0))
            #(f,s) = _get_real_values(fs)
	    a = toparse.pop(0);
	    b = toparse.pop(0);
	    c = toparse.pop(0);
	    d = toparse.pop(0);
	    e = toparse.pop(0);
	    f = toparse.pop(0);
	    g = toparse.pop(0);
	    h = toparse.pop(0);
	    i = toparse.pop(0);
	    print ord(f) & 0x7f, ord(g) & 0x7f
        else:
            toparse.pop(0)
    print ""

#####################
##### Functions #####
#####################
def configure_serial(ser):
    ser.baudrate = 115200               # 115200
    ser.bytesize = serial.EIGHTBITS     # 8
    ser.parity = serial.PARITY_NONE     # N
    ser.stopbits = serial.STOPBITS_ONE  # 1
    ser.xonxoff = 1                     # XON/XOFF flow control
    ser.timeout = 1
    ser.port = device

def get_raw_data(ser):
    sys.stdout.write("Connecting to device...")
    sys.stdout.flush()
    ser.open()
    sys.stdout.write("reading...")
    sys.stdout.flush()
    ser.write(b'\x7d\x81\xa1\x80\x80\x80\x80\x80\x80')
    raw = list(ser.read(9))
    while len(raw) >= 9:
        print ord(raw[5]) & 0x7f, ord(raw[6]) & 0x7f
        raw = ser.read(9)
    ser.close()
    if len(raw) <= 1:
        print("no data received. Is the device on?")
        exit(43)
    print("done!")
    return raw

def parse_raw_data(data):
    sys.stdout.write("Parsing data...", )
    sys.stdout.flush()
    parsed = []
    _parse_list(data, parsed)
    print("done!")
    return parsed

def get_len_of_parsed_data(parsed):
    return len(parsed) / 2 # 1Hz, two values (pulse and sats)

def write_to_file(parsed, total_len, f):
    sys.stdout.write("Writing to file...", )
    sys.stdout.flush()

    zeroval = _ple(0)
    f.write(_ple(856))
    f.write(_ple(1))
    for _ in range(212):
        f.write(zeroval)
    f.write(_ple(1))
    for _ in range(55):
        f.write(zeroval)
    f.write(_ple(total_len))
    for e in parsed:
        f.write(chr(e))

def change_starttime(f):
    if starttime != None:
        sys.stdout.write("changing start time...", )
        sys.stdout.flush()
        dt = parse(starttime, dayfirst=False, yearfirst=True)
        year = _ple(dt.year)
        month = _ple(dt.month)
        day = _ple(dt.day)
        hour = _ple(dt.hour)
        minute = _ple(dt.minute)
        second = _ple(dt.second)
        f.seek(0x420)
        s = year + month + day + hour + minute + second
        f.write(s)


################
##### Main #####
################
configure_serial(ser)
data = get_raw_data(ser)
parsed = parse_raw_data(data)
total_len = get_len_of_parsed_data(parsed)
f = open(outfile, 'wb')
write_to_file(parsed, total_len, f)
change_starttime(f)
f.close()
print("done!")