User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 241
www.energymicro.com
• Resume/Reset detection in EM2 (during suspend)
• SRP detection in EM2 (during host session off)
• Soft connect/disconnect
• Full OTG support
• Compliant with On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification,
Revision 2.0
• Compliant with USB On-The-Go Supplement, Revision 1.3
• Supports Host Negotiation Protocol (HNP) and Session Request Protocol (SRP)
• On-chip PHY
• Internal pull-up and pull-down resistors
• Voltage comparators for monitoring VBUS voltage
• A/B Device identification using ID line
• Charge/dischange of VBUS for VBUS-pulsing
• Internal 3.3V Regulator
• Output voltage: 3.3V
• Output current: 50 mA
• Input voltage range: 4.0 - 5.5V
• Enabled automatically when input voltage applied
• Low quiescent current: 100 uA
• Dedicated input pin allows regulator to be used in OTG and host configurations
• Output pin can be used to power the EFM32 itself as well as external components
• Regulator voltage output sense feature for detecting USB plug/unplug events (also available in
EM2/3)
15.3 USB System Description
An block diagram of the USB is shown in Figure 15.1 (p. 241) .
Figure 15.1. USB Block Diagram
OTG
PHY
USB_VBUS
Voltage
Regulator
(3.3 V)
USB_DP
USB_DM
USB_ID
USB_VREGI
USB_VREGO
AHB Master
AHB Slave
AHB
2 KB
FIFO RAM
USB_VBUSEN
VREGO
Sense
USB Core
w/ DMA Controller
APB Slave
APB
USB Interrupt
SOF PRS
USB_DMPU
USB System
(control)
The USB consists of a digital logic part, a 2 KB endpoint RAM, OTG PHY and a voltage regulator with
output voltage sensor. The voltage regulator provides a stable 3.3 V supply for the PHY, but can also
be used to power the EFM32 itself as well as external components.
The digital logic of the USB is split into two parts: system and core.