Table 581. Calibration Status Register Field Descriptions - STMicroelectronics SPC572L series Reference Manual

RM0400
44.3.16.3.4 Calibration Status Register (CSTAT)
Address: 0x2
0 1 2
R CALS 0
W
Reset 0 0 0
16 17 18
R
W
Reset 1 1 1
Field
Calibration State
00 Not_Calibrated
0:1
01 Basic_Calibrated
CALS
10 Precision_Calibrated
11 reserved
2 Reserved
0x000–0x3FF Time Quanta Counter
3:13
Captured number of time quanta in calibration field (32 or 64 bits). Only valid when the clock
TQC
calibration unit is in state Precision_Calibrated.
0x00000–0x3FFFF Oscillator Clock Period Counter
14:31
Captured number of oscillator clock periods in calibration field (32 or 64 bits). Only valid when the
OCPM
clock calibration unit is in state Precision_Calibrated.
44.3.16.3.5 Calibration Watchdog Register (CWD)
The calibration watchdog is started after the first falling edge when the calibration FSM is in
state Not_Calibrated (CSTAT.CALS = "00"). In this state the calibration watchdog monitors
the message received input (cu_mrx). In case no message was received until the
calibration watchdog has counted down to zero, the calibration FSM stays in state
Not_Calibrated (CSTAT.CALS = "00"), the counter is reloaded with RWD.WDC and basic
calibration is restarted after the next falling edge.
When in state Basic_Calibrated (CSTAT.CALS = "01"), the calibration watchdog is restarted
with each received message (cu_mrx = '1'). In case no message was received until the
calibration watchdog has counted down to zero, the calibration FSM returns to state
Not_Calibrated (CSTAT.CALS = "00"), the counter is reloaded with RWD.WDC and basic
calibration is restarted after the next falling edge.
When a quartz message was received, state Precision_Calibrated (CSTAT.CALS = "10") is
entered and the calibration watchdog is restarted. In this state the calibration watchdog
monitors the quartz message received input (cu_qmrx). In case no message from a quartz
controlled node was received by the attached M_CAN until the calibration watchdog has
3 4 5
0 0 0
19 20 21
1 1 1
Figure 534. Calibration Status Register (CSTAT)

Table 581. Calibration Status Register field descriptions

DocID027809 Rev 4
6 7 8 9
TQC
1 0 0 0
22 23 24 25
OCPC
1 1 1 1
Description
CAN Subsystem
10 11 12 13
0 0 0 0
26 27 28 29
1 1 1 1
Access: Read
14 15
OCPC
1 1
30 31
1 1
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