commit 017ebda429ec30aca096ff2eae4124bbc397aa54
Author: Scott Alfter <scott@alfter.us>
Date:   Fri Mar 28 12:39:52 2025 -0700

    initial commit

diff --git a/.gitignore b/.gitignore
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+++ b/.gitignore
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+*~
diff --git a/README.md b/README.md
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+UPS software for Geekworm X728
+==============================
+
+Install prerequisites:
+
+```sudo apt update && sudo apt install -y python3 python3-smbus python3-pip && sudo pip3 install --break-system-packages rpi-lgpio```
+
+Install the software:
+
+```sudo cp x728ups x728off /usr/local/bin && sudo cp x728ups.service /lib/systemd/system && sudo systemctl daemon-reload```
+
+Enable the software:
+
+```sudo systemctl enable x728ups.service && sudo systemctl start x728ups.service```
+
+Monitor the daemon while it's running:
+
+```journalctl -fu x728ups```
+
+Ways to do a clean shutdown
+---------------------------
+
+* ```sudo x728off``` (don't use ```shutdown -h now```)
+* send SIGUSR1 (this is what x728off does)
+* hold down the button for 4 seconds
+* unplug power and wait for the battery to get to 20% remaining
+
+Ways to reboot
+--------------
+
+* the old standby: ```shutdown -r now```
+* hold down the button for 1 second
+
+Kill the buzzer when on battery
+-------------------------------
+
+* send SIGUSR2: ```sudo pkill -USR2 -u root -f x728ups```
+
+Notes
+-----
+
+Tested on a Raspberry Pi 4B running Armbian Bookworm, with a Geekworm X728 v2.5.
diff --git a/x728off b/x728off
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+#!/usr/bin/env bash
+source /etc/profile
+sudo pkill -USR1 -u root -f x728ups
diff --git a/x728ups b/x728ups
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+++ b/x728ups
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+#!/usr/bin/env python
+import struct
+import RPi.GPIO as GPIO
+import smbus
+import time
+import subprocess
+import sys
+import signal
+
+GPIO_BUZZER_PIN=20  # controls the buzzer
+GPIO_ON_BATT=6      # set when running on battery
+GPIO_PWR_CTRL=26    # toggle this for 2 seconds before shutdown, or else the board won't respond to the first power-on event
+GPIO_BTN=5          # button signal: 500ms pulse for reboot, stays high for shutdown
+GPIO_BOOT=12        # enable the button
+I2C_ADDR=0x36       # the chip that reads battery charge state is here
+CRIT_BATT=20        # shut off at this percentage
+
+class X728UPS: 
+    
+    def __init__(self):
+        GPIO.setmode(GPIO.BCM)
+        GPIO.setup(GPIO_BUZZER_PIN, GPIO.OUT, initial=GPIO.LOW)
+        GPIO.setup(GPIO_PWR_CTRL, GPIO.OUT, initial=GPIO.LOW)
+        GPIO.setup(GPIO_ON_BATT, GPIO.IN)
+        GPIO.setup(GPIO_BOOT, GPIO.OUT, initial=GPIO.HIGH)
+        GPIO.setup(GPIO_BTN, GPIO.IN)
+        GPIO.add_event_detect(GPIO_BTN, GPIO.RISING, callback=lambda ch: self.ButtonCallback())
+        signal.signal(signal.SIGUSR1, self.Shutdown)
+        self.buzzer_on=True
+        signal.signal(signal.SIGUSR2, self.ToggleBuzzer)
+
+    def ToggleBuzzer(self, signum, frame):
+        self.buzzer_on=not self.buzzer_on
+        signal.signal(signal.SIGUSR2, self.ToggleBuzzer)
+
+    def Shutdown(self, signum, frame):
+        print("shutdown requested by SIGUSR1", flush=True)
+        GPIO.output(GPIO_PWR_CTRL, GPIO.HIGH)
+        time.sleep(2)
+        GPIO.output(GPIO_PWR_CTRL, GPIO.LOW)
+        subprocess.run(["shutdown", "-h", "now"])
+        sys.exit()
+
+    def ButtonCallback(self):
+        if GPIO.input(GPIO_BTN):
+            t=0
+            while GPIO.input(GPIO_BTN) and t<1000:
+                time.sleep(0.01)
+                t=t+10
+            if t>=200 and t<=600: # nominal 500ms pulse for reboot, or stays high for shutdown until powered off
+                print("reboot requested", flush=True)
+                time.sleep(1) # so the message above gets logged
+                subprocess.run(["shutdown", "-r", "now"])
+                sys.exit()
+            else:
+                print("shutdown requested", flush=True)
+                GPIO.output(GPIO_PWR_CTRL, GPIO.HIGH)
+                time.sleep(2)
+                GPIO.output(GPIO_PWR_CTRL, GPIO.LOW)
+                subprocess.run(["shutdown", "-h", "now"])
+                sys.exit()
+
+    def readVoltage(self, bus):
+        address = I2C_ADDR
+        read = bus.read_word_data(address, 2)
+        swapped = struct.unpack("<H", struct.pack(">H", read))[0]
+        voltage = swapped * 1.25 /1000/16
+        return voltage
+
+    def readCapacity(self, bus):
+        address = I2C_ADDR
+        read = bus.read_word_data(address, 4)
+        swapped = struct.unpack("<H", struct.pack(">H", read))[0]
+        capacity = swapped/256
+        return capacity
+
+    def main(self):
+        bus=smbus.SMBus(1)
+
+        while True:
+            v=self.readVoltage(bus)
+            c=self.readCapacity(bus)
+            if GPIO.input(GPIO_ON_BATT):
+                p="OB"
+            else:
+                p="OL"
+            if c<CRIT_BATT:
+                p="%s LB" % p
+            p="%s %1.2f %i" % (p, v, c)
+            print(p, flush=True)
+            if p.find("OB")!=-1: # on battery?
+                if p.find("LB")!=-1: # low battery?
+                    print("low battery shutdown", flush=True)
+                    if self.buzzer_on:
+                        GPIO.output(GPIO_BUZZER_PIN, GPIO.HIGH)
+                    GPIO.output(GPIO_PWR_CTRL, GPIO.HIGH)
+                    time.sleep(2)
+                    GPIO.output(GPIO_PWR_CTRL, GPIO.LOW)
+                    subprocess.run(["shutdown", "-h", "now"])
+                    while True: # wait forever
+                        time.sleep(1) 
+                else: # on battery, but not low
+                    if self.buzzer_on:
+                        GPIO.output(GPIO_BUZZER_PIN, GPIO.HIGH)
+                    time.sleep(.25)
+                    GPIO.output(GPIO_BUZZER_PIN, GPIO.LOW)
+                    time.sleep(4.75) 
+            else: # online
+                time.sleep(5)
+
+app=X728UPS()
+app.main()
diff --git a/x728ups.service b/x728ups.service
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+++ b/x728ups.service
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+[Unit]
+Description=X728 UPS
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/x728ups
+Restart=always
+StandardError=journal
+StandardOutput=journal
+StandardInput=null
+
+User=root
+Group=root
+
+[Install]
+WantedBy=multi-user.target