21. Universal Serial Bus (USB0)
21.1 Introduction
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.
USBn Module
Serial Interface Engine (SIE)
Internal USBn
Oscillator
Clock Recovery
to SYSCLK mux
Data Transfer
Control
Control
Status
Endpoint 0
IN
OUT
USB FIFO
space in
External RAM
USBn_EP1 Endpoint
IN
OUT
USBn_EP2 Endpoint
IN
OUT
USBn_EP3 Endpoint
IN
OUT
D+
D-
Transceiver
VDD
Figure 21.1. USB Block Diagram
21.2 Features
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.
EFM8UB3 Reference Manual
Universal Serial Bus (USB0)
silabs.com
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