Pin Description - American Dynamics ADRL3TRK Series Service Manual

ATMEGA 128 pin description
Pin Description
VCC Digital Supply Voltage
GND Ground
Port A (PA7...PA0) These ports are 8-bit, bi-directional
I/O ports with internal pull-up
Port B (PB7...PB0)
resistors (selected for each bit). Their
Port C (PC7...PC0)
output buffers have symmetrical drive
characteristics with high sink and
Port D (PD7...PD0)
source capability. As inputs, these
Port E (PE7...PE0)
ports pins externally pulled low will
source current if the pull-up resistors
Port F (PF7...PF0)
are activated. Their pins are tri-state
when a reset condition becomes
active, even if the clock is not
running.
Note: Port F also serves as the
analog input to the A/D converter. If
the JTAG interface is enabled, the
pull-up resistors on pin PF7 (TDI),
PF5 (TMS) and PF4 (TCK) activate
even if a reset occurs. The TDO pin
is tri-state unless TAP states that
shift out data are entered. Port F also
serves functions of the JTAG
interface.
Port G (PG7...PG0) Port G is a 5-bit, bi-directional I/O
port with internal pull-up resistors
(selected for each bit). Port G output
buffers have symmetrical drive
characteristics with high sink and
source capability. As inputs, Port G
pins externally pulled low will source
current if the pull-up resistors are
activated. Port G pins are tri-state
when a reset condition becomes
active, even if the clock is not
running.
RESET A low level on this pin for longer than
the minimum pulse length generates
a reset, even if clock is not running.
XTAL1 Input to the inverting oscillator
amplifier and internal clock operating
circuit.
XTAL2 Output from the inverting oscillator
amplifier.
AVCC A/D converter externally connected
to Vcc.
AREF Analog reference pin for the A/D
converter.
PEN Programming enable pin for the SPI
serial programming mode. Holding
this pin low during a power-on reset
causes the device to enter the SPI
serial programming mode. PEN has
no function during normal operation.
SENSORRAIL IIIE
SERVICE GUIDE
Motor Command
When the ATMEGA microcontroller receives an
IRIS or FOCUS command, it sends one of four
output signals to the PWM driver (sampling
frequency is 25kHz).
• PWM: Digital value directly related to the
movement speed of the trolley (1–256 steps).
• Cmd (0 or 1): Value related to the rotation (CW
or CCW) depending on the known position of
the trolley along the rail as given by the
encoder.
• Disable (0 or 1): Value used to inhibit or not
inhibit PWM drivers (motor ON or OFF).
• Brake (0 or 1): Value used to command the
relay of the brake device. To slow and stop the
motor, the relay turns off and a dissipative
resistor shunts the motor. During the braking
process, the motor is disconnected from power.
Speed is maintained using rotation pulses and the
synchronization top pulse from the encoder, fixed
to the motor, the encoder sends 500 pulses per
rotation through its channel plus a synchronization
top pulse per rotation.
Several speeds are available depending on
commands sent to the µP:
• Manual nominal speed: 3m/s (9.84ft/s)
• Initialization speed: 1m/s (3.28ft/s)
• Patrol mode: 1.5m/s (4.92ft/s)
• Preset speed: 6m/s (19.69ft/s)
• Preset positioning speed: 0.3 m/s (0.98ft/s)
One motor rotation corresponds to a 7.8125cm
(3.08in) movement along the rail. For example,
when the trolley is moving along the rail at 1m/s
(3.28ft/s), the motor rotates at 12.8RPS (768RPM).
A 16-bit internal counter performs the speed
calculation. The counter is incremented by the VA
channel from the encoder and read once every
10ms.
Speed is calculated by comparing the difference
between two counter readings multiplied by 100,
and then divided by 64. For example (speed in
cm/s): 100 cm/s = 768 RPM = 384000 pulses/min
= 6400 pulses/sec = 64 pulses/10ms.
The PWM value update (real speed of the trolley
comparing the user requested speed) is performed
once every 0.5 sec.
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8200-0593-03, REV. A