Datasheet

TOF_Down Command (01h)
The TOF_DOWN command generates a single TOF
measurement in the downstream direction. Pulses launch
from the LAUNCH_DN pin and are received by the
STOP_DN pin. The measured hit results are reported in
the HITxDnInt and HITxDnFrac registers, with the calcu-
lated average of all the measured hits being reported in
the AVGDNInt and AVGDNFrac register. The t
1
/t
2
and t
2
/
t
ideal
wave ratios are reported in the WVRDN register.
Once all these results are stored, then the TOF bit in the
Interrupt Status register is set and the INT pin asserts (if
enabled).
Note: The TOF_Down command yields a result that is
only of use when used in conjunction with the TOF_UP
command. Absolute TOF measurements include circuit
delays and cannot be considered accurate.
TOF_DIFF Command (02h)
The TOF_DIFF command performs back-to-back TOF_
UP and TOF_DN measurements as required for a meter-
ing application. The TOF_UP sequence is followed by the
TOF_DN sequence. The time between the start of the
TOF_UP measurement and the start of the TOF_DN mea-
surement is set by the TOF_CYC[2:0] bits in the TOF2
register. Upon completion of the TOF_DN measurement,
the results of AVGUP minus AVGDN is computed and
stored at the TOF_DIFFInt and TOF_DIFFFrac Results
register locations. Once these results are stored, then the
TOF bit in the Interrupt Status register is set and the INT
pin asserts (if enabled).
Temperature Command (03h)
The temperature command initiates a temperature mea-
surement sequence as described in the Temperature
Measurement Operations section. The characteristics the
temperature measurement sequence depends upon the
settings in the Event Timing 1 register, and Event Timing
2 register. Once all the measurements are completed, the
times measured for each port are reported in the corre-
sponding TxInt and TxFrac Results registers. The TE bit
in the Interrupt Status register also is set and the INT pin
asserts (if enabled).
Reset Command (04h)
The reset command essentially performs the same func-
tion as a power-on reset (POR), and causes all of the
Configuration registers to be set to their prior programmed
values stored in flash and all of the Results registers and
the Interrupt Status register to be cleared and set to zero.
Initialize Command (05h)
The initialize command must be executed after all con-
figuration of the device is complete. This initializes the
time-to-digital converter so that TOF and temperature
commands can be executed. The MAX35101 sets the
INIT bit in the Interrupt Status register and asserts the
INT device pin (if enabled) to tell the host microprocessor
that the initialize command has completed and the next
desired command can be sent to the MAX35101.
Transfer Conguration to
Flash Command (06h)
This command causes the Configuration register map
to be transferred to flash for nonvolatile (NV) storage.
The MAX35101 automatically turns on the LDO for the
duration of this transfer. Upon device reset, the content
of this flash restores the Configuration registers. This
flash is not part of the 8KB array, and is reserved solely
for the transfer configuration to the flash command. The
MAX35101 sets the flash bit in the Interrupt Status regis-
ter and asserts the INT device pin (if enabled) to tell the
host microprocessor that the transfer configuration to the
flash command has completed and the next command
can be sent to the device.
EVTMG1 Command (07h)
The EVTMG1 command initiates the event timing mode
1 advanced automatic measurement feature. This timing
mode performs automatic TOF_DIFF and Temperature
measurements as described in the Event Timing
Operation section. The duration of the automatic mea-
surements depends upon the settings in the Event Timing
1 register, Event Timing 2 register, CONT_INT and ET_
CONT bits in the Calibration and Control register.
EVTMG2 Command (08h)
The EVTMG2 command initiates the event timing mode
2 advanced automatic measurement feature. This timing
mode performs automatic TOF_DIFF measurements as
described in the Event Timing Operation section. The
duration of the automatic measurements depends upon
the settings in the Event Timing 1 register, CONT_INT
and ET_CONT bits in the Calibration and Control register.
MAX35101 Time-to-Digital Converter with Analog Front-End
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