Week 2: January 23 to January 29, 2012

Hardware Development & Testing

The components have been ordered from element 14 (formerly known as Farnell Components (M) Sdn. Bhd.) on 27^th January 2012. The components are:

No.	Components	Quantity	Application
1.	PIC16F877A	2	Controller
2.	Network resistor 2.2kΩ	2	Motor driver
3.	Variable resistor / Trimmer 100Ω	2	Motor driver
4.	Resistor 510Ω (1/8 watt)	10 (min quantity)	Motor driver
5.	Resistor 1Ω (1/2 watt)	50 (min quantity)	Motor driver
6.	SLA 7024M Unipolar Stepper Motor Driver	2	Motor driver
7.	Crystal 20Mhz	2	Controller
8.	Inductor 330µH	2	Voltage regulator
9.	Distance Measuring Sensor	3	IR sensor
10.	Network resistor 47kΩ	2	Motor driver

The total cost for this order is RM 287.55. I have ordered extra units for each component for testing purposes except for the motor drivers because these are the last two pieces available at element 14. Therefore, I have to come out with some back up for motor driver in case of faulty or damage. There are a few types of drivers that might be suitable to be used with Sanyo Denki unipolar stepper motor that I used. One of them is by using the SLA7062M Unipolar Stepper Motor Translator/ Drivers. This device is a complete microstepping motor driver with built in translator for easy operation with minimal control lines. This device will let you drive a unipolar stepper motor at voltages up to 46 Volts and 3A per phase. It employs an internal PWM control of motor current which is can be set by a pair of external resistors. It is designed to operate unipolar stepper motors in half, quarter, eight and sixteenth step modes. This mode can be selected by sending bits to the input M1 and M2 as below:

Input M1	Input M2	Step Mode
High	High	Half Step
High	Low	Quarter Step
Low	High	Eight Step
Low	Low	Sixteenth Step

SLA7062M

Another option is by using L297 stepper motor controller with quad darlington array ULN2075B. I am also planning to do some testing using ULN2003 to find out whether this device is capable to drive my stepper motors which has current rating of 1A/phase. 

In the meantime, I did some testing on IR01 sensor which I bought from Cytron Technologies. This sensor is an infrared sensor and is used for detecting obstacle. If an obstacle is detected, it will output logic high and the led will on. It also has a trimmer to allow adjustment of the distance the sensor capable to operate. In my testing I found out that this sensor is capable to detect as close as 8 mm (distance between sensor and the object) and as far as 10 cm. Since it has a digital output, it is cannot be used to measure the distance between the robot and the wall, therefore this sensor may be unsuitable for this project.

IR01 sensor

Reference:
http://www.micromouseonline.com/2007/07/20/motor-driver-chip/#ixzz1mI6Wj6l2