Transcript Special Sensor Report - University of Florida

Special Design Report
IMDL Summer 2002
Matthew Chernosky
July 11, 2002
Overview
Additional hardware Pulse Width
Modulation channels
 Need for additonal PWM channels
 Design
 Results

Need for additional channels

Atmel ATMega163
– 3 PWM channels built-in

Motion
– Requires 2 channels (left and right)

Golf ball pickup
– Needs more than one channel
Design
2 additional channels to be
implemented
 Channels used for locomotion
 Altera MAX7032 CPLD
 Development in VHDL

Design

3 Settings for each channel
– Forward
– Reverse
– Stopped
A 2-bit wide input bus selects desired
setting for each channel
 4 output port pins of uP

Design
1 MHz
oscillator
Chan A select
Atmel
Mega163
PWM A Out
Altera
MAX7032
Chan B select
CPLD
Microcontroller
PWM B Out
Design
Reset
1 MHz clock
15-bit
counter
Logic
FF
PWM A
FF
PWM B
Chan A select
Chan B select
CPLD
VHDL
ENTITY motor_pwm_580 IS
PORT(
clk : in STD_LOGIC;
PWM_IN_A: in STD_LOGIC_VECTOR(1 downto 0);
PWM_IN_B: in STD_LOGIC_VECTOR(1 downto 0);
PWM_OUT_A: out STD_LOGIC;
PWM_OUT_B: out STD_LOGIC
);
END motor_pwm_580;
VHDL
cnt: PROCESS (clk)
BEGIN
IF (clk = '1' and clk'EVENT) THEN
if (count < COUNT_MAX) then
-- increment counter
count <= count + 1;
else
-- reset counter when COUNT_MAX reached
count <= COUNT_RST;
end if;
END IF;
END PROCESS;
Results
Oscilliscope
waveform tests
 Works with
servos

1.75 ms
20 ms