Information
43.4.4 TIMER0 Register (USBDCD_TIMER0)
TIMER0 has an TSEQ_INIT field that 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, however the USB Battery Charging
Specification requires the entire sequence, including TSEQ_INIT, to be completed in 1s
or less.
Address: USBDCD_TIMER0 is 4003_5000h base + 10h offset = 4003_5010h
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
TSEQ_INIT
0 TUNITCON
W
Reset
0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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 current elapsed time since software set the CONTROL[START] bit plus the value of
TSEQ_INIT. The timer is initially loaded with the value of TSEQ_INIT before starting to count.
This timer enables compliance with the maximum time allowed to connect (TUNIT_CON) under the USB
Battery Charging Specification, v1.1.If the timer reaches the TUNIT_CON 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.
Memory Map/Register Definition
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
1098 Freescale Semiconductor, Inc.