Week 11: March 29, 2012 (Thursday)

Hardware - Motor Driver

Constructing the SLA 7024M motor driver on a single hole board.

Week 11: March 28, 2012 (Wednesday)

Hardware - SLA 7024M Motor Driver

Today, again I try to change the sequence in the program and connection from the driver output to motor but it didn’t work. Finally I found in the internet, the driver input and output should be in the sequence A, B, A/, B/. So, I change the input connection from PIC and output connections to motor and it works.

SLA motor driver test circuit

Week 11: March 27, 2012 (Tuesday)

Hardware - Upgrading Motor Driver

Since the voltage regulator has an output of 1A, I decided to upgrade the motor driver to 1A so that higher current can be injected to the motor as the motor rated curent is 1A. So, I constructed a test circuit for SLA7024M motor driver. The motor was running when connected to the driver but something wrong with the sequence. The motor spin CW and CCW repeatedly. I tried to change the connections for a few times but still didn't work. In the meantime, I goggle on the internet to find a battery with higher capacity that can last at least 15 minutes. Then I found a Ni-MH battery 7.2V 3300 mAH at www.rcsmart.com.my. The shop is located at Amcorp Mall PJ. I am planning to go there on Friday to see the dimension and the weight of the battery.

SLA7024M motor driver

7.2V 3300 mAH battery

Week 10: March 25, 2012 (Sunday)

Hardware - LM2575 Voltage Regulator

It's time to construct the LM2575 voltage regulator on a single hole board. 

LM2575 voltage regulator

Voltage regulator (back view)

The output voltage

The output voltage is 4.99V which is very good and close to 5V.

Week 10: March 23, 2012 (Friday)

Hardware - Testing Voltage Regulator

Today, I ran a test on LM2575 voltage regulator circuit that I have constructed yesterday. The circuit is functioning very well. I'm so happy :)
 

Testing circuit for LM2575

Output voltage from LM2575

Week 10: March 22, 2012 (Thursday)

Hardware - Upgrade Voltage Regulator

Since Robomouse was not running very well yesterday, I decided to change and reposition the battery. So, now the 9V battery is connected to regulator to supply power to PIC and sensors as well as to the motor driver while the 7.2V rechargeable battery is connected to the motor. Robomouse start running but only can stand for a few minutes only. However, I can see the changes where the wheel spin quite smoothly compared to yesterday. Previously, the battery is located next to the motor, on top of the ball caster. The weight of the battery had pressing the ball caster and produce friction and this caused the wheel to stuck. Now, the battery is located on the platform next to the regulator board. But still the battery is sinking so fast. Robomouse has to withstand at least 10 - 15 minutes in the competition.

In order to inject higher current to drive the motor, I decided to construct another voltage regulator using LM 2575. According to the datasheet this IC can produce a 1A current. As usual, I build a test circuit on a breadboard before constructing it on a single hole board. In the evening, I went to Pasar Road to buy some components.

Components for the regulator

Week 10: March 21, 2012 (Wednesday)

Hardware - Power Consumption

Today I'm adding a 10 uF capacitor between gnd and vcc pin (+5V) on regulator circuit board for the sensor. 

 

Bypass capacitor (next to the header pin) to stabilize the sensor power supply

 

I ran a test on the Robomouse but it didn’t run smoothly and looks like it is too heavy to move or stuck somewhere. Perhaps the battery is not enough to drive the motor. The battery is sinking so fast and just after a few runs the motors become stall. I switched the supply from battery to power supply from the digital trainer and test run but with the chassis upside down to see if there is something stuck in the wheel but it seems that the wheel run smoothly when it is not touching the ground. So, it is not something to do with the wheel. Still searching for the cause...