MAX11410 Datasheet, PDF (34/95 Pages) Maxim Integrated Products – 24-Bit Multi-Channel Low-Power

MAX11410
24-Bit Multi-Channel Low-Power
1.9ksps Delta-Sigma ADC with PGA
Sequencer
The sequencer is a powerful feature that allows a
sequence of commands to be programmed into the
sequence buffer (µC0-µC52 registers). When a sequence
is initiated by a write to the SEQ_START register or (when
configured) a rising edge on a GPIO pin, the sequencer
will serially execute commands as if it were the SPI
master writing those commands to the control registers.
The initiated sequence will begin executing at the address
in the SEQ_ADDR or GP_SEQ_ADDR, depending on
which is selected. Sequences will execute until a PD
command is encountered or until the sequencer is
interrupted by a write from the SPI master. If no PD
command is encountered, the sequence will execute in a
loop and wrap around from µc52->µC0.
All µC registers are '0000' by default, which corresponds
to a 'PD:Normal' commmand. PD commands function as
a sequence stop. The completion of a sequence can be
configured to generate an interrupt via the SEQ_RDY_IE
bit. A wraparound, a PD execution, or a SEQ_START
inside of a sequence will cause the assertion of SEQ_
RDY. As with a continuous conversion with CONV_RDY,
executing the sequencer in a loop will auto-clear SEQ_
RDY prior to re-asserting it.
Using a SEQ_START command within the sequencer
microcode will function as a GOTO statement, enabling
multiple continuous sequences to be programmed into
the sequencer’s µC register space. A CONV_START,
CAL_START, or WAIT_START command will prevent
the sequencer from advancing until the command is
completed. Sequence timing can be controlled with a
WAIT_START command. Wait durations should be
programmed according to the settling time of the associated
internal and external circuitry.
The currently executing microcode address and data can
be read back via the read-only µCADDR register. The
µCADDR[6:0] can be read back at any time to determine
the currently executing microcode address. A read of
0x00 indicates that the sequencer is inactive. Values of
0x3A-0x6E indicate an active sequence.
Active sequences are exited by a write to any register,
resetting the µCADDR register to 0x00. Launching a
sequence does not reset the control registers. All register
states will be retained, either as a result of a prior write or
a prior sequence execution.
Sequencer Notes
1. Registers with 24-Bit data operands (UTHRESH,
LTHRESH, SELF_OFF, STATUS_IE, etc) are not
supported in sequencer mode. Programming a register
that has a 24-bit operand into a µC register will result
in a '0000' or 'PD' being written to the µC register.
2. Writing a µC address to a µC register will result in a
'0000' or 'PD' being written to the register.
Sequencer Example
Below is shown a populated sequence buffer. Three
SEQ_START examples are discussed below:
1) The interface executes SEQ_START <µC0>
The sequencer will execute the commands shown (con-
figure the input multiplexer, select buffered signal path,
wait, convert and store in data location 1, configure the
input multiplexer, wait, convert and store in data location
2, initiate a power down, issue a SEQ_RDY status, and
halt the sequence at register µC7.
2) The interface executes SEQ_START <µC8>
The sequencer will execute the commands starting at
µC8 and continuing through µC48 in a loop until the the
sequencer is interrupted with a write to the interface. This
sequence configures the input multiplexer for various
combinations of AIN0 through AIN0, performing a conver-
sion with a variety of PGA settings, storing the results
in DATA0->DATA7. A SEQ_RDY will be asserted at the
end of the sequence (µC48) and deasserted when the
sequence starts again (µC8).
3) The interface executes SEQ_START <µC49>
The Sequencer will execute the commands shown
from address µC49 (program the input multiplexer and
filter, wait, perform a self-calibration) and wraparound
continuing execution at µC0. Ultimately, the sequencer
will initiate a power down, issue a SEQ_RDY status, and
halt the sequence at register µC7.
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