The UPS HAT (D) by Waveshare is an add-on board designed for Raspberry Pi devices to provide uninterruptible power supply functionality. It ensures continuous operation during power outages by utilizing a rechargeable lithium battery. This HAT is particularly useful for applications requiring high reliability, such as IoT devices, servers, or remote monitoring systems.

• IoT Devices: Ensures uninterrupted operation of Raspberry Pi-based IoT systems.
• Data Logging: Prevents data loss during unexpected power failures.
• Remote Monitoring: Keeps remote systems operational during power outages.
• Home Automation: Provides backup power for critical home automation tasks.
• Portable Projects: Enables mobility by acting as a power source for Raspberry Pi.

The UPS HAT (D) is equipped with advanced features to ensure reliable power delivery and monitoring. Below are the key technical details:

The UPS HAT (D) connects to the Raspberry Pi via the GPIO header. Below is the pin configuration:

The UPS HAT (D) is easy to integrate with Raspberry Pi. Follow the steps below to set it up and use it effectively:

1. Attach the HAT: Align the UPS HAT (D) with the Raspberry Pi GPIO header and gently press it into place.
2. Connect the Battery: Attach a compatible lithium battery to the JST connector on the HAT.
3. Power Input: Optionally, connect a 5V power source to the micro-USB port or GPIO header.

1. Enable I2C: On your Raspberry Pi, enable I2C communication using raspi-config:

   sudo raspi-config
   

   Navigate to Interfacing Options > I2C and enable it.
2. Install Required Libraries: Install the Python smbus library for I2C communication:

   sudo apt-get update
   sudo apt-get install python3-smbus i2c-tools
   

3. Verify I2C Connection: Check if the UPS HAT (D) is detected on the I2C bus:

   i2cdetect -y 1
   

   You should see the device address (e.g., 0x36) in the output.

The following Python code demonstrates how to read the battery voltage and percentage from the UPS HAT (D):

import smbus
import time

bus = smbus.SMBus(1) # Use I2C bus 1 on Raspberry Pi DEVICE_ADDRESS = 0x36 # Default I2C address of UPS HAT (D)

def read_voltage(): # Read raw voltage data (2 bytes) raw = bus.read_word_data(DEVICE_ADDRESS, 0x02) # Swap byte order and convert to voltage voltage = ((raw & 0xFF) << 8 | (raw >> 8)) * 1.25 / 1000 return voltage

def read_capacity(): # Read raw capacity data (2 bytes) raw = bus.read_word_data(DEVICE_ADDRESS, 0x04) # Swap byte order and convert to percentage capacity = ((raw & 0xFF) << 8 | (raw >> 8)) / 256 return capacity

while True: voltage = read_voltage() capacity = read_capacity() print(f"Battery Voltage: {voltage:.2f}V") print(f"Battery Capacity: {capacity:.2f}%") time.sleep(5) # Wait 5 seconds before the next reading

• Battery Selection: Use only compatible lithium-ion or lithium-polymer batteries with appropriate capacity and voltage ratings.
• Ventilation: Ensure proper ventilation to prevent overheating during charging.
• Shutdown Procedure: Use the Raspberry Pi's shutdown command before disconnecting the UPS HAT to avoid data corruption.
• Firmware Updates: Check the Waveshare website for firmware updates or additional resources.

1. HAT Not Detected on I2C Bus:

   • Ensure I2C is enabled in raspi-config.
   • Verify the HAT is properly seated on the GPIO header.
   • Check the I2C address using i2cdetect -y 1.

2. Battery Not Charging:

   • Confirm the battery is connected securely to the JST connector.
   • Ensure the input power supply provides sufficient current (at least 1A).

3. Raspberry Pi Shuts Down Unexpectedly:

   • Check the battery capacity and charge level.
   • Verify the HAT is supplying 5V to the Raspberry Pi.

4. Incorrect Voltage or Capacity Readings:

   • Ensure the Python script is using the correct I2C address.
   • Verify the battery is functioning properly.

Q: Can I use the UPS HAT (D) with other single-board computers?
A: While designed for Raspberry Pi, the UPS HAT (D) can be used with other devices that support 5V input and I2C communication. However, software compatibility may vary.

Q: What is the maximum runtime on battery power?
A: The runtime depends on the battery capacity and the power consumption of your Raspberry Pi. For example, a 3000mAh battery can power a Raspberry Pi 4 (idle) for approximately 2-3 hours.

Q: Is it safe to leave the HAT connected to power continuously?
A: Yes, the UPS HAT (D) includes overcharge protection to ensure safe operation during continuous use.

Q: Can I monitor the battery status programmatically?
A: Yes, the HAT provides battery voltage and capacity data via I2C, which can be accessed using the example Python code provided above.