Information

USBDCD_TIMER0 field descriptions
Field Description
31–26
Reserved
This read-only field is reserved and always has the value zero.
25–16
TSEQ_INIT
Sequence Initiation Time
TSEQ_INIT represents the system latency (in ms) measured from the time VBUS goes active to the time
system software initiates the charger detection sequence in the USBDCD module. When software sets
the CONTROL[START] bit, the Unit Connection Timer (TUNITCON) is initialized with the value of
TSEQ_INIT. Valid values are 0-1023, but the USB Battery Charging Specification requires the entire
sequence, including TSEQ_INIT, to be completed in 1s or less.
15–12
Reserved
This read-only field is reserved and always has the value zero.
11–0
TUNITCON
Unit Connection Timer Elapse (in ms)
Displays the amount of elapsed time since the event of setting the START bit plus the value of
TSEQ_INIT. The timer is automatically initialized with the value of TSEQ_INIT
This timer enables compliance with the maximum time allowed to connect T
UNIT_CON
under the USB
Battery Charging Specification, v1.1.If the timer reaches the one second limit, the module triggers an
interrupt and sets the error flag STATUS[ERR].
The timer continues counting throughout the charger detection sequence, even when control has been
passed to software. As long as the module is active, the timer continues to count until it reaches the
maximum value of 0xFFF (4095 ms). The timer does not rollover to zero. A software reset clears the
timer.
41.4.5 TIMER1 register (USBDCD_TIMER1)
TIMER1 contains timing parameters. Note that register values can be written that are not
compliant with the USB Battery Charging Specification v1.1, so care should be taken
when overwriting the default values.
Address: USBDCD_TIMER1 is 4003_5000h base + 14h offset = 4003_5014h
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R
0
TDCD_DBNC
0
TVDPSRC_ON
W
Reset
0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0
USBDCD_TIMER1 field descriptions
Field Description
31–26
Reserved
This read-only field is reserved and always has the value zero.
25–16
TDCD_DBNC
Time Period to Debounce D+ Signal
Sets the time period (ms) to debounce the D+ signal during the data pin contact detection phase. See
"Debouncing the data pin contact"
Valid values are 1–1023, but the USB Battery Charging Specification requires a minimum value of 10 ms.
Table continues on the next page...
Chapter 41 USB Device Charger Detection Module (USBDCD)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 935