Controller Chip. FT639 Datasheet

FT639 Chip. Datasheet pdf. Equivalent

Part FT639
Description Servo Controller Chip
Feature www.DataSheet4U.com FerretTronics Control Circuits http://www.ferrettronics.com/ FerretTronics FT6.
Manufacture ETC
Datasheet
Download FT639 Datasheet




FT639
FerretTronics Control Circuits http://www.ferrettronics.com/
FerretTronics FT639 Servo
Controller Chip
Data Sheet
General Description:
The FT639 is an RC servo controller chip. The FT639 will
control five radio-controlled servos through one 2400 baud
serial line. It has a footprint of only eight pins. The only
external components required are two resistors and a diode for
an normal RS232 line such as the one found on a personal
computer. No components are needed for a 0-5 volt serial line
such as those found on the Parallax Basic Stamp . Just
connect the servo control lines directly to the chip and connect
the serial in line from a 2400 baud, No parity, 1 stop bit serial
source, and five RC servos can be controlled, (see circuit
setup).
Applications:
Radio control servo motors are used in remote control model
airplanes, cars, and boats. They are widely available and can be
used in robotics, automation, animation, and many other tasks.
The problem with using RC servo motors in the past was the
ability to control them. With the FT639 this is no longer a
problem. It is possible now to control five RC servo motors
with just one 2400 baud serial line. Each of the five RC servos
is independently controlled.
Voltage on V++:
Voltage on 2400 Baud
In:
Serial Line Setup:
3.0V - 5.5V
< = V++
2400 Baud, 8 Bit, No
parity, and 1 Stop Bit
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FT639
FerretTronics Control Circuits http://www.ferrettronics.com/
Operations:
FT639 has two operating modes: Setup mode and Active mode.
The chip starts in Setup mode. Setup mode is used to set the
pulse length, header length and starting values for the 5 servos.
Active mode sends the control pulses to the servos and controls
the servos through the 2400 baud serial line.
Commands are sent to the FT639 through a 2400 baud, 8 bit,
no parity, 1 stop bit serial line. The commands are all one byte.
Each command is one character sent over the 2400 baud serial
line.
Each RC servo has 256 positions. To send the position of a
servo to the FT639 requires two commands. The first command
contains the servo number and the lower nibble (lower 4 bits)
of the positional number. The second command contains the
servo number and the upper nibble (upper 4 bits) of the
positional number.
The FT639 can set a typical servo in 256 different positions
from 0 to 90 degrees with the short pulse length, or can control
a typical servo in 256 different positions from 0 to 180 degrees
with the long pulse length. The starting position of the servo
can also be adjusted by using a different header length. The
header length can be adjusted in the setup mode.
Setup Mode:
The servo controller starts in Setup mode. The default settings
are the header is approximately 1ms with a short pulse length.
This will control a typical servo in 256 steps from 0 to 90
degrees.
In setup mode the following settings can be adjusted:
1. Header length--this will allow adjustment of the starting
position of the servo. The default setting is 12.
2. Servo pulse length--this allows positioning control of
the servo between 0 to 90 degrees with the shorter pulse
length or positioning control of the servo between 0 to
180 degrees with the longer pulse length. The default
setting is short pulse length.
3. Initial setup of the servo positions--the FT639 will not
send positioning pulses to the servo in Setup mode.
However, positioning commands can be sent to the
FT639 while in setup mode to allow the servos to
energize in a known position. The default setting is
position 0.
The following commands can be sent in Setup mode:
Command
Active Mode
Short Pulse
Long Pulse
Binary Decimal
Value Value
01110101
117
01010101
85
01011010
90
The header length command is 0110xxxx, where xxxx is the
setting for the header length. The actual length of the header
will be different for the different pulse length as shown below:
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