1.6 Communications and Other Digital Peripherals
Universal Serial Bus (USB0)
The USB0 peripheral provides a full-speed USB 2.0 compliant device controller and PHY with additional Low Energy USB features. The
device supports both full-speed (12MBit/s) and low speed (1.5MBit/s) operation, and includes a dedicated USB oscillator with clock re-
covery mechanism for crystal-free operation. No external components are required. The USB function controller (USB0) consists of a
Serial Interface Engine (SIE), USB transceiver (including matching resistors and configurable pull-up resistors), and 1 KB FIFO block.
The Low Energy Mode ensures the current consumption is optimized and enables USB communication on a strict power budget.
The USB0 module includes the following features:
• Full and Low Speed functionality.
• Implements 4 bidirectional endpoints.
• Low Energy Mode to reduce active supply current based on bus bandwidth.
• USB 2.0 compliant USB peripheral support (no host capability).
• Direct module access to 1 KB of RAM for FIFO memory.
• Clock recovery to meet USB clocking requirements with no external components.
• Charger detection circuitry with automatic detection of SDP, CDP, and DCP interfaces.
• D+ and D- can be routed to ADC input to support ACM and proprietary charger architectures.
Universal Asynchronous Receiver/Transmitter (UART1)
UART1 is an asynchronous, full duplex serial port offering a variety of data formatting options. A dedicated baud rate generator with a
16-bit timer and selectable prescaler is included, which can generate a wide range of baud rates. A received data FIFO allows UART1
to receive multiple bytes before data is lost and an overflow occurs.
UART1 provides the following features:
• Asynchronous transmissions and receptions.
• Dedicated baud rate generator supports baud rates up to SYSCLK/2 (transmit) or SYSCLK/8 (receive).
• 5, 6, 7, 8, or 9 bit data.
• Automatic start and stop generation.
• Automatic parity generation and checking.
• Four byte FIFO on transmit and receive.
• Auto-baud detection.
• LIN break and sync field detection.
• CTS / RTS hardware flow control.
Serial Peripheral Interface (SPI0)
The serial peripheral interface (SPI) module provides access to a flexible, full-duplex synchronous serial bus. The SPI can operate as a
master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select
(NSS) signal can be configured as an input to select the SPI in slave mode, or to disable master mode operation in a multi-master
environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be
configured as a firmware-controlled chip-select output in master mode, or disabled to reduce the number of pins required. Additional
general purpose port I/O pins can be used to select multiple slave devices in master mode.
• Supports 3- or 4-wire master or slave modes.
• Supports external clock frequencies up to 12 Mbps in master or slave mode.
• Support for all clock phase and polarity modes.
• 8-bit programmable clock rate (master).
• Programmable receive timeout (slave).
• Two byte FIFO on transmit and receive.
• Can operate in suspend or snooze modes and wake the CPU on reception of a byte.
• Support for multiple masters on the same data lines.
EFM8UB3 Reference Manual
System Overview
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