1. IMDL Summer 2002 Matthew Chernosky July 11, 2002
Special Design Report
IMDL Summer 2002
Matthew Chernosky
July 11, 2002

2. Overview Additional hardware Pulse Width Modulation channels
Need for additonal PWM channels
Design
Results

3. 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

4. Design 2 additional channels to be implemented
Channels used for locomotion
Altera MAX7032 CPLD
Development in VHDL

5. 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

6. Design 1 MHz oscillator Atmel PWM A Out Mega163 Altera MAX7032
Chan A select
Altera
MAX7032
PWM A Out
PWM B Out
Chan B select
CPLD
Microcontroller

7. Design 15-bit counter FF Logic FF CPLD Reset PWM A 1 MHz clock PWM B
Chan A select
Chan B select
CPLD

8. 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;

9. 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;

10. Results
Oscilliscope waveform tests
Works with servos
1.75 ms
20 ms