MC1151A PMD, MC1151A Datasheet - Page 17

• Manufacturer Part Number: MC1151A
• Description: (MC1x51A) Advanced Step Motor Control Chipset
• Manufacturer: PMD

Theory of Operations
The above figure shows an internal block diagram for the MC1451A
and MC1451A-E Motion Processors.
The MC1451-series chipsets consist of two chips, an ASIC (Application
Specific I.C.) called the I/O chip and a DSP (Digital Signal Processor)
called the CP chip. The MC1451-E series chipsets consist of these
same two chips along with an additional ASIC chip called the ENC chip.
The function of the I/O ASIC is to perform host I/O as well as pulse
generation. The function of the CP chip is to perform all motion
computations. The function of the ENC chip is to perform quadrature
position decoding.
The chipset supports up to four axes simultaneously. Each axis
provides programmable trajectory generation including electronic
gearing, trapezoidal point-to-point, s-curve point to point, and a velocity
contouring mode.
The chipset calculates all trajectory information on a cycle-by-cycle
basis. Each cycle results in a new desired pulse rate based on the
trajectory generator mode and the specified trajectory parameters. By
Control
Home
Input
5
1/a
Host I/O controller
Motor Output Signals
I/O Chip
Host I/O
Pulse & Direction
Step
Generator (1-4)
Data
1/a
8
Direction
host interrupt
1/a
1
Internal Block Diagram
Host command
Trajectory profile
generator (1-4)
System Registers (1-4)
CP Chip
Miscellaneous Signals
17
Overtravel Inputs
PosLimit
1/a
feeding the resulting pulse rate to the pulse generating circuitry of the
I/O ASIC at each cycle, continuous and smooth motion is achieved for
all four axes.
The I/O ASIC provides high speed pulse and direction generation
appropriate for interfacing to a wide variety of standard stepper drivers.
Two pulse rate operating modes are provided, one which results in a
pulse rate range of 0 - ~48,000 pulses per second (standard range),
and one which results in a pulse rate range of 0 - ~1,500,000 pulses per
second (high speed range).
The encoder feedback, which is available through the optional ENC
chip, is updated at each chipset cycle. This information can be used by
the host to check that the axis has achieved a desired position.
Additionally, the chipset can use the encoder information to
automatically detect a motor stall condition while a move is ongoing.
The following table summarizes the operational parameters of the
MC1451-series chipsets.
At Rest
1/a
NegLimit
1/a
Encoder Inputs
counter (1-4)
B
Quadrature
1/a
ENC
Chip
decoder
A
1/a