1.2 Power
Control over the device power consumption can be achieved by enabling/disabling individual peripherals as needed. Each analog pe-
ripheral can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers and serial buses, have their
clocks gated off and draw little power when they are not in use.
Table 1.1. Power Modes
Power Mode
Details
Mode Entry
Wake-Up Sources
Normal
Core and all peripherals clocked and fully operational
—
—
Idle
• Core halted
• All peripherals clocked and fully operational
• Code resumes execution on wake event
Set IDLE bit in PCON0
Any interrupt
Suspend
• Core and peripheral clocks halted
• HFOSC0 and HFOSC1 oscillators stopped
• Regulators in normal bias mode for fast wake
• Timer 3 and 4 may clock from LFOSC0
• Code resumes execution on wake event
1. Switch SYSCLK to
HFOSC0
2. Set SUSPEND bit in
PCON1
• USB0 Bus Activity
• Timer 4 Event
• SPI0 Activity
• Port Match Event
• Comparator 0 Falling
Edge
• CLUn Interrupt-Enabled
Event
Stop
• All internal power nets shut down
• 5V regulator remains active (if enabled)
• Internal 1.8 V LDO on
• Pins retain state
• Exit on any reset source
1. Clear STOPCF bit in
REG0CN
2. Set STOP bit in
PCON0
Any reset source
Snooze
• Core and peripheral clocks halted
• HFOSC0 and HFOSC1 oscillators stopped
• Regulators in low bias current mode for energy sav-
ings
• Timer 3 and 4 may clock from LFOSC0
• Code resumes execution on wake event
1. Switch SYSCLK to
HFOSC0
2. Set SNOOZE bit in
PCON1
• USB0 Bus Activity
• Timer 4 Event
• SPI0 Activity
• Port Match Event
• Comparator 0 Falling
Edge
• CLUn Interrupt-Enabled
Event
Shutdown
• All internal power nets shut down
• 5V regulator remains active (if enabled)
• Internal 1.8 V LDO off to save energy
• Pins retain state
• Exit on pin or power-on reset
1. Set STOPCF bit in
REG0CN
2. Set STOP bit in
PCON0
• RSTb pin reset
• Power-on reset
1.3 I/O
Digital and analog resources are externally available on the device’s multi-purpose I/O pins. Port pins P0.0-P1.6 can be defined as gen-
eral-purpose I/O (GPIO), assigned to one of the internal digital resources through the crossbar or dedicated channels, or assigned to an
analog function. Port pins P2.0 and P2.1 can be used as GPIO. Additionally, the C2 Interface Data signal (C2D) is shared with P2.0.
The port control block offers the following features:
• Up to 17 multi-functions I/O pins, supporting digital and analog functions.
• Flexible priority crossbar decoder for digital peripheral assignment.
• Two drive strength settings for each port.
• Two direct-pin interrupt sources with dedicated interrupt vectors (INT0 and INT1).
• Up to 17 direct-pin interrupt sources with shared interrupt vector (Port Match).
EFM8UB3 Reference Manual
System Overview
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