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Robotics Research Laboratory
Louisiana State University
DC Motor Controller (TB6612FNG)
MOSFET-based H-bridges
Metal–Oxide–Semiconductor
Field-Effect Transistor
int main(void){
InitHardware();
// ----------- PWM setting -------------//
ICR3 = 40000u;
// input capture registor --> pulse cycle every 40 milli seconds
TCNT3 = 0;
// interupt flag registor
// Set the WGM mode & prescalar for oscillating timer ( TCCR3A & TCCR3B : Timer control registors)
TCCR3A = ( 1 << WGM31 ) | ( 0 << WGM30 ) | ( 1 << COM3A1 ) | ( 1 << COM3B1 ) | ( 1 << COM3C1 );
TCCR3B = ( 1 << WGM33 ) | ( 1 << WGM32 ) | TIMER3_CLOCK_SEL_DIV_8;
DDRE |= (( 1 << 3 ) | ( 1 << 4 ) | ( 1 << 5 ));
// I/O control registor (PWM pins as outputs)
MC_HI(STANBY); MC_LO(LEFT0); MC_LO(LEFT1); MC_LO(RIGHT0); MC_LO(RIGHT1);
int speed = 1000;
int delay = 100;
while (1){
MC_LO(LEFT0);MC_HI(LEFT1);
OCR3A = speed;
ms_spin(delay);
MC_HI(LEFT0);MC_LOW(LEFT1);
speed += 1000;
if (speed > 40000){
speed = 1000;
}
}
}
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Converting a continuous quantity to a
discrete time digital representation
Converting an analog voltage to a digital
value that can be used by a microcontroller.
There are many sources of analog signals to
be measured such as light intensity,
temperature, distance, position, etc.
The reverse operation is performed by a
digital-to-analog converter (DAC).

The number of discrete values it can produce over
the range of analog values.
◦ Usually stored electronically in binary form
◦ The number of discrete values available, or "levels", is a
power of two. (ex) 8bits  Range from 0 to 255
Resolution =
V ref-High - V ref-Low
2n
◦ where n is the ADC's resolution
in bits
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ATMega128 ADC has 10 bits resolution
◦ What is the range?
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Has 8 channels through a multiplexer
◦ 8 pins on PORTF
◦ Need to set PORTF as input without pull-up
◦ How to set this up?
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Has own power supply (labeled AVCC)
Allows measuring voltages from 0 to 5 volts
with a resolution of 5/1024 volts, or 4.88 mV
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Can be configured in several different ways
Single-ended� mode : the analog voltages
presented on the ADC channels are compared
to ground.
There are several selectable voltage
references, which determine the range of the
ADC conversion. (ex) AVCC
Free-running mode (update continuously) or
only one conversion.
Quantity
Symbol
Unit of
measurement
Unit of
Abbreviation
Current
I
Ampere (“Amp”)
A
Voltage
V or E
Volt
V
Resistance
R
Ohm
Ω
E = IR , I = E / R , or R = E / I
I= E/R
+
5V
0V drop = 10 mA x 0 Ω
4V
1V drop = 10 mA x 100 Ω
R1 = 100 Ω
5V
-
10 mA = 5 V / 500 Ω
R2 = 400 Ω
0V
4V drop = 10 mA x 400 Ω
First calculate current ( I ) by using E / R (5 / 500 = 0.01)
Then calculate voltage drop at each point based on Ohm’s Law
E=IxR
(R1 = 0.01 * 100 , R2 = 0.01 * 400)
5V
+
S1 = 0 ~ 20000 Ω
Connect to ADC
5V
-
0V drop = Xi mA x 0 Ω
X V drop = Xi mA x S1 Ω
R2 = 1000 Ω
0V
X v+ restV drop = Xi mA x 1000Ω
Resistance value of S1(IR sensor) can be changed by sensing
uint16_t a2d_10( uint8_t Channel ){
// Select the channel in a manner which leaves REFS0 and REFS1 un touched.
ADMUX = ( ADMUX & (( 1 << REFS1 ) | ( 1 << REFS0 ))) | Channel;
// Start the conversion
ADCSR = ADCSR | ( 1 << ADSC );
// Wait for it to complete
while ( ADCSR & ( 1 << ADSC ));
return ADC;
// ADC defined at avr/iom128.h
( special function register: SFR_IO16)
} // a2d_10
/home/csc2700/csc2700/40-ADC-01
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Config.h
◦ Set : #define CFG_USE_UART0 1
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Hardware.h
◦ Set : #define UART0_BAUD_RATE
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57600
ADC_test.c
◦ Add : #include "UART.h”
◦ Create file pointer : FILE *u0; // for UART0
◦ Open u0
 if defined( __AVR_LIBC_VERSION__ )
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 #else
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 #endif
u0 = fdevopen( UART0_PutCharStdio, UART0_GetCharStdio );
u0 = fdevopen( UART0_PutCharStdio, UART0_GetCharStdio, 0 );
◦ Send values using fprintf(u0,”your message %d”, variable);
/home/csc2700/csc2700/40-ADC-02
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Our programmer has 2 serial port
◦ ttyACM0 : ISP programming port
◦ ttyACM1 : UART serial port
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Wire connection
◦ PE0
◦ PE1
◦ GND
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 Yellow wire
 Green wire
 Black wire
Open Gtk-term
◦ Set port : /dev/ttyACM1
◦ Speed : 57600