Information

Table 41-14. Overview of the charger detection sequence
Phase Overview description Full description
1 Initial Conditions Initial system conditions that need to be met before the detection sequence is
initiated.
Initial System
Conditions
2 VBUS Detection System software detects contact of the VBUS signal with the system interrupt
pin VBUS_detect.
VBUS contact
detection
3 Data Pin Contact
Detection
The USBDCD module detects that the USB data pins D+ and D– have made
contact with the USB port.
Data pin contact
detection
4 Charging Port
Detection
The USBDCD module detects if the port is a standard host or either type of
charging port, that is charging host or dedicated charger.
Charging port
detection
5 Charger Type
Detection
The USBDCD module detects the type of charging port, if applicable. Charger type
detection
6 Sequence
Timeout
The USBDCD module did not finish the detection sequence within the timeout
interval. The sequence will continue until halted by software.
Charger
detection
sequence
timeout
Timing parameter values used in this module are listed in the following table.
Table 41-15. Timing parameters for the charger detection sequence
Parameter USB Battery Charging Spec Module default
Module
programmable range
T
DCD_DBNC
1
10 ms min (no max) 10 ms 0– 1023 ms
T
VDPSRC_ON
1
40 ms min (no max) 40 ms 0 –1023 ms
T
VDPSRC_CON
1
40 ms min (no max) 40 ms 0 –1023 ms
CHECK_DM N/A 1 ms 0– 15 ms
T
SEQ_INIT
N/A 16 ms 0 –1023 ms
T
UNIT_CON
1
1 s N/A N/A
T
VDMSRC_EN
1
1– 20 ms From the USB host N/A
T
VDMSRC_DIS
1
0 –20 ms From the USB host N/A
T
CON_IDPSINK_DIS
1
0– 20 ms From the USB host N/A
1. This parameter is defined by the USB Battery Charging Specification, v1.1.
41.5.1.1 Initial System Conditions
The USBDCD module can be used only with FS USB device applications using a
rechargable battery. That is, it cannot be used with USB applications that are HS, LS,
host, or OTG. In addition, before the USBDCD module's charger detection sequence can
be initiated, the system must be:
• Powered-up and in run mode.
Functional description
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
940 Freescale Semiconductor, Inc.