982
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
38.5
Typical Connection
Figure 38-2. Board Schematic to Interface Device Peripheral
38.5.1
USB Device Transceiver
The USB device transceiver is embedded in the product. A few discrete components are
required as follows:
• The application detects all device states as defined in chapter 9 of the USB specification;
– VBUS monitoring
• To reduce power consumption the host is disconnected
• For line termination.
38.5.2
VBUS Monitoring
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a stan-
dard PIO with internal pullup disabled. When the host is switched off, it should be considered as
a disconnect, the pullup must be disabled in order to prevent powering the host through the pull-
up resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating.
This may lead to over consumption. A solution is to enable the integrated pulldown by disabling
the transceiver (TXVDIS = 1) and then remove the pullup (PUON = 0).
A termination serial resistor must be connected to DDP and DDM. The resistor value is defined
in the electrical specification of the product (R
EXT
).
38.6
Functional Description
38.6.1
USB V2.0 Full-speed Introduction
The USB V2.0 full-speed provides communication services between host and attached USB
devices. Each device is offered with a collection of communication flows (pipes) associated with
each endpoint. Software on the host communicates with a USB device through a set of commu-
nication flows.
R
EXT
R
EXT
DDM
DDP
PIO
27 K
47 K
Type B
Connector
1
2
3
4
5V Bus Monitoring
Содержание SAM4S Series
Страница 44: ...44 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Страница 412: ...412 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Страница 1105: ...1105 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Страница 1142: ...1142 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 3 100 ball VFBGA Package Drawing ...
Страница 1143: ...1143 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 4 64 lead LQFP Package Drawing ...
Страница 1145: ...1145 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 5 64 lead QFN Package Drawing ...