UG-1262
Rev. B | Page 302 of 312
STATUS 6 REGISTER
Address: 0x40001488, Reset: 0x7900, Name: SR6
SR6 is a status register that provides the unread status of snapshots of input capture channels, SNAP0, SNAP1, and SNAP2.
Table 396. Bit Descriptions for SR6
Bits Bit
Name
Settings
Description
Reset
Access
[15:11] Reserved
Reserved.
0xF
R
[10:9] RTCFRZCNTPTR
Pointer for the Triple Read Sequence of the CNTx MMRs. This bit indicates the
sequence number for the next read in triple read sequences of the CNTx registers.
CNTx allows a coherent triple 16-bit read of the 47-bit WUT count contained in
CNT2, CNT1, and CNT0. CNTx is always read in sequences of three reads (although
these can be spread out in time, or have other APB accesses interspersed), so that
the first read in the sequence returns the current value of CNT0. Simultaneously
with this first read, a snapshot is taken of the values of CNT2 and CNT1 so that in
the second and third reads in the sequence of CNTx, the snapshot values of
CNT1 and CNT2 are returned, respectively. In this way, a triple read of CNTx gives
an overall 47 bits of the WUT count that belong together and are coherent with
each other, even though the actual continuing value of CNT2, CNT1, and CNT0
keeps advancing while the WUT counts real time. This bit both indicates the
sequence number in the triple read and acts a read data select for the value
returned when CNTx is read. Normally, this bit keeps advancing by one, starting
from 0b00, and wrapping from 0b10 to 0b00 with every read. However, to clear
the CNTx pointer and reinitialize the count sequence for reads of CNTx, the CPU
can write a software key (value of 0x9376) to the GWY register.
0x0 R
00
The next read of CNTx causes the read data for CNTx to be the current value of
CNT0 and takes a coherent snapshot of the current values of CNT2 and CNT1 for
return during the subsequent two reads of CNTx. The value that can be read in
SNAP0, SNAP1, and SNAP2 is due to a software initiated snapshot.
01
The next read of CNTx is the second in a triple read sequence and returns the
snapshot of CNT1 that was taken when the first read of CNTx in the sequence
occurred.
10
The next read of CNTx is the third in a triple read sequence and returns the snapshot
of CNT2 that was taken when the first read of CNTx in the sequence occurred.
[8:0]
Reserved
Reserved.
0x100 R