So, just to close out this thread I thought I'd post a now working version of the python code. It doesn't (yet) use the nicer code unpacking that deanhystad suggested but it works...
Thank you for the feedback as it was invaluable in helping me figure this stuff out...
#!/usr/bin/env python3
# This code should be run as SUDO as it does low level BLE scanning.
#
# Run it as follows:
#
# sudo python jbd-bms-mqtt.py -n "Cabin 580ah" -i 0 -t solar
# or
# sudo python jbd-bms-mqtt.py -a "a4:c1:38:30:c2:8e" -i 0 -t solar
#
# This will scan for a bluetooth device called "Cabin 580ah" and extract its
# bluetooth address, or, use the passed address if provided, then try and attach
# to the BMS and read a set if variables, one time, and then publish a MQTT
# message with those variables to the Topic "solar".
#
# USAGE NOTE
# If you use a value other than 0 for the -i parm the program will loop forever
# and read the BMS values every X minutes based on the value you passed. This is
# not recommended as a long term method to run the script, as it could cause
# resource issues in the python environment. For an ongoing run please use a
# cron job to control run times and pass a 0 for the -i argument...
#
# In addition, if you run this program via a manual shell loop instead of using
# cron, and someone attached to the BMS using a bluetooth app (like XiaoxiangBMS
# or SmartBMSUtility) the code will fail when it attempts to connect (as the other
# app has the connection) and will throw an exception. If you started it intending
# it to run "forever" in a terminal window you will not realize it's failed.
#
# If cron is used, at least the process will be kicked off again based on the cron
# process and try to reconnect again, automatically...
#
# You've been warned!
from bluepy.btle import Peripheral, DefaultDelegate, BTLEException
from bluepy.btle import Scanner, DefaultDelegate
import sys
import struct
import argparse
import json
import time
import binascii
import atexit
import paho.mqtt.client as paho
def disconnect():
mqtt.disconnect()
print("broker disconnected")
def cellinfo1(data): # process battery info
print("Processing (dd03) battery info...")
infodata = data
# Unpack into variables, skipping header bytes 0-3
volts, amps, remain, capacity, cycles, mdate, balance1, balance2 = struct.unpack_from('>HhHHHHHH', infodata, 4)
volts = volts / 100
amps = amps / 100
capacity = capacity / 100
remain = remain / 100
global ginfo
ginfo.append(volts)
ginfo.append(amps)
ginfo.append(capacity)
ginfo.append(remain)
print(ginfo)
time.sleep(timeSleep)
def cellvolts1(data): # process cell voltages
print("Processing (dd04) cell volts message...")
celldata = data
# Unpack into variables, skipping header bytes 0-3
cell1, cell2, cell3, cell4 = struct.unpack_from('>HHHH', celldata, 4)
global ginfo
ginfo.append(cell1)
ginfo.append(cell2)
ginfo.append(cell3)
ginfo.append(cell4)
print(ginfo)
time.sleep(timeSleep)
class MyDelegate(DefaultDelegate): # When the device replies this code is invoked to deal with it
def __init__(self):
DefaultDelegate.__init__(self)
def handleNotification(self, cHandle, data):
hex_data = binascii.hexlify(data) # Given raw bytes, get an ASCII string representing the hex values
text_string = hex_data.decode('utf-8') # Check incoming data for routing to decoding routines
if text_string.find('dd03') != -1: # x03
cellinfo1(data) # Decode and process BMS info
elif text_string.find('dd04') != -1: # x04
cellvolts1(data) # Decode and process cell info
else:
print("Why Am I Here? What is this data", text_string)
# Mainline Code
# Process command line arguments and set up variables
parser = argparse.ArgumentParser(description='Fetches and outputs JBD bms data')
parser.add_argument("-n", "--name", help="BLE Device Name", required=False)
parser.add_argument("-a", "--address", help="BLE Device Address", required=False)
parser.add_argument("-i", "--interval", type=int, help="Read interval in minutes, 0=One & Done", required=True)
parser.add_argument("-t", "--topic", help="MQTT Topic name", required=True)
args = parser.parse_args()
loopMinutes = args.interval * 60 # Takes the input value and turns it into minutes
topic = args.topic # Topic to use when posting to MQTT
bleName = args.name # BLE device Name that will be scanned for to get address
bleAddrP = args.address # BLE address that will be used rather than a BLE name
timeSleep = 1 # Used to slow things down a bit in case of timing issues
ginfo = list() # Global list to hold elements from the various requests
broker = "192.168.1.98" # Change this to your MQTT broker address
port = 1883 # Default port that MQTT is listening on
# Resolve the BLE device address using a name or a provided address
if not bleAddrP and not bleName:
sys.exit("Process needs either a ble Name or ble Address...Halting!")
elif bleName:
print("Searching for ble Name = '%s'" % bleName)
scanner = Scanner()
devices = scanner.scan(5) # Scan for 5 seconds
print("============ Scanning Results ==============")
for dev in devices:
for (adtype, desc, value) in dev.getScanData():
print("Device = '%s' Name = '%s'" % (dev.addr, value))
if value == bleName:
print("=========== Found It ==============")
print("Name = %s" % value)
print("Device = %s" % dev.addr)
print("RSSI = %d dB" % dev.rssi)
print("===================================")
bleAddr = dev.addr
else:
bleAddr = bleAddrP # Use the command line parm address
try: # If the variable was created above the BLE device was found
bleAddr
except NameError:
sys.exit("Do not have a usable BLE device address...Halting!")
# Main Loop Logic Begins Here
while True:
try: # Attempt a connection with the BMS via BLE
print('Attempting to connect...')
bms = Peripheral(bleAddr, addrType="public")
except BTLEException as ex:
time.sleep(30) # timeSleep not used here, this waits 30 seconds between attempts
print('1st attempt failed, trying 2nd time to connect...')
bms = Peripheral(bleAddr, addrType="public")
except NameError:
sys.exit("Can not connect to the BLE device...Halting!")
# This means something went wrong as there is a ble address to use but it could not
# be connected. Maybe some other application has the connection already and someone
# forgot to disconnect when they were done configuring the BMS.
else:
print('Connected...', bleAddr)
atexit.register(disconnect) # run the disconnect function when with the loop
mqtt = paho.Client("control3") # create and connect mqtt client
mqtt.connect(broker, port)
bms.setDelegate(MyDelegate()) # setup BlueTooth process delegate to get returned notifications
# write x03 record to request battery info
resultx03 = bms.writeCharacteristic(0x15, b'\xdd\xa5\x03\x00\xff\xfd\x77', False)
bms.waitForNotifications(5) # waiting 5 seconds as less seems to cause missed notifications
# write x04 record to request cell volts info
resultx04 = bms.writeCharacteristic(0x15, b'\xdd\xa5\x04\x00\xff\xfc\x77', False)
bms.waitForNotifications(5) # waiting 5 seconds as less seems to cause missed notifications
time.sleep(timeSleep)
# Disconnect from BMS BLE connection. This allows other applications and tools the chance
# to connect to the BMS via Bluetooth.
bms.disconnect()
# Load the JSON message with the merged BMS data and send it via MQTT
time.sleep(timeSleep)
gvolts = ginfo[0]
gamps = ginfo[1]
gcapacity = ginfo[2]
gremain = ginfo[3]
gcellvolt1 = ginfo[4]
gcellvolt2 = ginfo[5]
gcellvolt3 = ginfo[6]
gcellvolt4 = ginfo[7]
message0 = {
"topic": topic,
"volts": gvolts,
"amps": gamps,
"capacity": gcapacity,
"remain": gremain,
"cell1": gcellvolt1,
"cell2": gcellvolt2,
"cell3": gcellvolt3,
"cell4": gcellvolt4
}
ret = mqtt.publish(topic, payload=json.dumps(message0), qos=0, retain=False)
if loopMinutes != 0: # Loop unless interval is 0, otherwise one & done
while len(ginfo) > 0: # If looping the ginfo list needs to be cleaned or it just grows and grows
del ginfo[0]
time.sleep(loopMinutes)
else:
break
