Register Manual

The UPS HAT (E) primarily uses I2C communication to read module information, making it simple and convenient to use. The module slave address is: 0x2D.

Register Table

ID Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x00	R	0x0a	0000 1010

Power-On Trigger Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x01	R/W	0x0b	0000 1011

warning

0x01 is a one-time shutdown trigger register, not the auto-start-on-power configuration register. After writing 0x55 to 0x01, the module initiates a delayed shutdown sequence: it cuts power to the Raspberry Pi after about 30 seconds, and then begins detecting charging after about 60 seconds. When power is detected, the module re-applies power to the Raspberry Pi and boots it. Auto-start-on-power is controlled by BIT0 of 0x40, with a default value of 1. Before performing the write, you must save data and prepare for a safe shutdown.

Charging Status Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x02	R		1: Charging 0: Not charging	1: Fast charge 0: Not fast charge	1: VBUS powered 0: VBUS not powered	Fixed: 00		000: Standby, 001: Trickle charge, 010: Constant current charge, 011: Constant voltage charge, 100: Charging waiting, 101: Full charge, 110: Charge timeout

Communication Status Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x03	R		Fixed: 000000						1: BQ4050 communication OK; 0: BQ4050 communication error	1: IP2368 communication OK; 0: IP2368 communication error

Type-C VBUS Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x10	R		Low 8 bits of VBUS voltage data (mV)
0x11	R		High 8 bits of VBUS voltage data (mV)

Type-C VBUS Current Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x12	R		Low 8 bits of VBUS current data (mA)
0x13	R		High 8 bits of VBUS current data (mA)

Type-C VBUS Power Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x14	R		Low 8 bits of VBUS power data (mW)
0x15	R		High 8 bits of VBUS power data (mW)

Battery Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x20	R		Low 8 bits of total battery voltage data (mV)
0x21	R		High 8 bits of total battery voltage data (mV)

Battery Current Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x22	R		Low 8 bits of battery current data (mA)
0x23	R		High 8 bits of battery current data (mA), signed 16-bit; positive indicates charge current, negative indicates discharge current

Battery Remaining Percentage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x24	R		Low 8 bits of battery remaining percentage data (%)
0x25	R		High 8 bits of battery remaining percentage data (%)

Battery Remaining Capacity Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x26	R		Low 8 bits of battery remaining capacity data (mAh)
0x27	R		High 8 bits of battery remaining capacity data (mAh)

Battery Remaining Discharge Time Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x28	R		Low 8 bits of battery remaining discharge time data (min)
0x29	R		High 8 bits of battery remaining discharge time data (min)

Battery Remaining Charge Time Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x2a	R		Low 8 bits of battery remaining charge time data (min)
0x2b	R		High 8 bits of battery remaining charge time data (min)

Battery 1 Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x30	R		Low 8 bits of battery 1 voltage data (mV)
0x31	R		High 8 bits of battery 1 voltage data (mV)

Battery 2 Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x32	R		Low 8 bits of battery 2 voltage data (mV)
0x33	R		High 8 bits of battery 2 voltage data (mV)

Battery 3 Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x34	R		Low 8 bits of battery 3 voltage data (mV)
0x35	R		High 8 bits of battery 3 voltage data (mV)

Battery 4 Voltage Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x36	R		Low 8 bits of battery 4 voltage data (mV)
0x37	R		High 8 bits of battery 4 voltage data (mV)

Control Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x40	R/W	0x01	Reserved						1: Watchdog enable; 0: Watchdog disable (default)	1: Auto-start on power (default); 0: Auto-start on power disable

Custom UPS I2C Address

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x41	R/W	0x2d	I2C address range: 0x08–0x77, default: 0x2d

Watchdog Timeout Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x42	R/W	0xFF	Range: 0–255, unit: s, default: 0xFF

Watchdog Delay Start Register

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x43	R/W	0xFF	Range: 0–255, unit: s, default: 0xFF

Software Version

Register	R/W	Default	BIT7	BIT6	BIT5	BIT4	BIT3	BIT2	BIT1	BIT0
0x50	R		Software version; shifting the decimal point left by one digit gives the software version, e.g. 0x14 = 20 = V2.0