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参数资料
| 型号： | 4255 |
| 厂商： | Allegro MicroSystems, Inc. |
| 英文描述： | OSC 5V 14PIN TTL |
| 中文描述： | 8位微控制器 |
| 文件页数： | 5/8页 |
| 文件大小： | 142K |
| 代理商： | 4255 |
4255
8-BIT
MICROCONTROLLER
www.allegromicro.com
3 125 full steps per second (50 kHz/16). These frequen-
cies represent the attainable limits with the A4255.
Although not a necessity, a stepping clock with a 50%
duty cycle represents the simplest technique for providing
an appropriate (
≤50 kHz) stepping clock rate. The step
clock varies depending upon the start, acceleration,
slewing, deceleration, and stop trajectories mandated by
the motion system control and ‘point-to-point’ timing
objectives.
Reset input
The preprogrammed microcontroller incorporates two
‘software’ reset states that are serially loaded with MS2,
MS1, and MS0 all high. However, the direct hardware
reset is actuated with a logic 0 (active low) on this input
An input low level defaults to the 0000 binary state and
sets the rotor to its natural (or detent) position with one-
phase energized.
Monitor output
An output low signal indicates a rotor alignment
corresponding to a single phase on position. Any changes
in the operating mode (microstepping to full-step, etc.)
should coincide with the interval that the monitor output is
in the low state. This alleviates noise problems, excessive
ringing, etc. that may result from changing the stepping
modes on-the-fly. Nonlinear (such as S-curve) accelera-
tion profiles can exploit this signal to achieve very
smooth, quiet stepper operation.
Shift clock output
This I/O terminal serves a dual purpose. On power
up, the microcontroller samples this terminal as an input.
Connecting a pull-up resistor results in 1/8th-step format;
while a pull-down resistor configures the controller for its
1/16th-step mode (A3957 only). This provides versatility,
simplicity, and cost-effectiveness for most users.
Operating in its output mode, this I/O constitutes the
shift clock signal for the 74HC595. Data is transferred
from the microcontroller serial-data output to the serial-
data input of the 74HC595. This 8-bit serial format is
converted into parallel signals controlling the 3-bit (or 4-
bit) DAC input lines to the two microstepping power ICs.
Serial data from the serial data output is valid on the low-
to-high clock transitions and eight clock pulses shift serial
control signals into the 74HC595. A basic timing diagram
(showing serial data, shift clock, and strobe) is depicted.
Signal timing is controlled by the preprogrammed micro-
controller; data entered into the 74HC595 shift register is
then latched by the low-to-high transition of the strobe
input.
ST
SCLK
Dwg. WP-040A
SDO
D7
D6
D5
D4
D3
D2
D1
D0
Serial data, shift clock, and strobe
Serial data output
The binary signal instructions that control each of the
microstepping power ICs is shown in table 1. The first
3-bits (or 4-bits) control the digital-to-analog conversion
in one power IC, while the next 3 (or 4-bits) ratio the
second power driver current. The microcontroller moni-
tors all the various static inputs (i.e., Direction, Mode
Selects, Reset), and by exploiting the Stepping Clock for
its input frequency, transfers the 8-bit data commands to
the power driver ICs via the serial-to-parallel interface IC.
The microcontroller utilizes look-up tables to provide
overall control of direction, stepping format, and recircu-
lation mode (PFD). The microcontroller reads inputs and
then outputs time-based signals to control both microstep-
ping ICs.
Strobe output
After the 8-bit serial data has been loaded into the
shift register, a low-to-high transition on the strobe output
transfers the serial data from the shift register into the
eight ‘D’ flip-flops that compose the parallel-data outputs.
This ‘latched’ data controls microstepping current ratios
for both power ICs, and is ‘updated’ after eight step
clocks.
FUNCTIONAL DESCRIPTION (cont’d)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 4255 | 制造商:3M Electronic Products Division 功能描述:RESPIRATOR A2P2 |
| 42550 | 制造商:Desco Industries Inc 功能描述:MAT 3-LYR VNYL BL .125''X16''X24 制造商:Desco Industries Inc 功能描述:MAT, STATFREE Z2, 3-LAYER VINYL, BLUE, 0.125x16x24 |
| 425-50,8MM(R06933) | 制造商:3M Electronic Products Division 功能描述:Aluminium adhesive tape 3M 425 50 mm |
| 425-5020-530 | 制造商:TERADYNE 功能描述:HEADER CONNECTOR,PCB MNT,RECEPT,80 CONTACTS,PIN,0.100 PITCH,PC TAIL TERMINAL |
| 42550X55 | 制造商:3M Electronic Products Division 功能描述:425 aluminium foil tape,55m Lx50mm W |
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