Customised ATMEGA328P Hardware with Multiple Problems- Please Help

Hi, I have started building a PCB a while ago the brain of which is ATMEGA328P.. The circuit can control two IRL530NS transistors and contain a shield for Easydriver...

The circuit works fine you can see the following Youtube video: http://www.youtube.com/watch?v=OAGcEoj_yQ0 http://www.youtube.com/watch?v=NZWJd15LaTI The above circuit was specifically made for DAVID LASER SCANNER control hardware... It has capability to control LCD display, 12Watt Light a Laser and motor controller.... I have posted the build process of the above circuit in David laser Scanner forum: http://www.david-laserscanner.com/forum/viewtopic.php?f=9&t=2655 LATEST UPDATES AND PROBLEM My controller can not do plane-less scanning and it can't interface with the laser scanner software.. This is because i have no Serial port connection at micro-controller hardware to send/get data from the Scanner software through Laptop USB port... I searched the Internet and found some expensive USB FTDI cables 15 US Dollar up to 20US Dollars.. :( that is not a cheap option... So decided to hack Nokia data cable CA-45 for that... Today i went to bazar and searched a CA-45 cable and i found it 80Pakistani Rupees( I US dollar=86 Rupees).. It has only 4-pins out toward the Mobile side connector and very close pins... Difficult to find the right pins i.e. GND, TXd and Rxd..... I put a small wedge at the edge and the connector pop out into two.. and i found only 3-wires coming out of connectors..RED, BLACK and WHITE... the RED one was connected to the external body of the connector, so in first guess i found it GND.. but to confirm, i used multimeter and it was GND, the BLACK and GND gave me 3.5 Volts and WHITE and GND gave me some 0.2V DC.. As the TX pin is always at high voltage as compare to Rx so found that the BLack=Tx..I also found that the Device appears as COM5 in device manager.. Hurra..that was a success....

As windows 7 has no Hyperterminal available so i downloaded a 30 days trial of "Hyperterminal Private Edition".. Then i combine the Rx and Tx pins and started the terminal with : “Bits per second:” to 115200 “Data bits:” to 8 “Parity:” to None “Stop bits:” to 1 “Flow control:” to None and COM5 port selected and typed in Hyperterminal window... and the Keyboard keys Echoed on the hyperterminal window.. so my Tx and Rx pins are rightly identified..

HURDLES- I NEED YOUR HELP: i was able to communicate through Hyperterminal by combining the Rx and Tx connections of CA-45. Todays when i connected the cable wires to Rx and Dx pins of Arduino and Gnd to the common Ground.. I checked the DEVICE MANAGER got the PoRT COM1 and device was recognizable.. The Arduino IDE also got the COM1, even the Hyperterminal got the COM1too but...

1- The David Software unable to recognize the COM port as when i set both the toggle switch to AUTO and enetred all the settings as MATTIA described in his planeless scanning tutorial..The LCD display did not show COM1:( :( :( 2- The Hyperterminal was unable to open the port COM1.

3- The Arduino was not able to upload sketches..

SOME MORE EXPLANATION OF PROBLEMS

1- In above pictures, The different COM ports is because i change the COM ports is DEVICE MANAGER from COM1 to COM10, to check why the Arduino not connected....So you see COM5 and COM1 in different screen shots...

2- My Arduino RESET button do not work.. I don't know why.... If you see in the picture... If i press the RESET button it should restart the David program, but it not doing....

3- The Tx and Rx from the USB is connected to Rx and Tx pins of arduino respectively. This is because Arduino need it to connected like this for cross talk...

4- When i remove the ATMEGA328P and install on the original Arduino, the RESET , RX and Tx works because i can upload new sketches... This also means that the IC legs are not faulty.. Their may be some fault in my DIY Arduino schematic, so i am posting the drawing for all of you to trouble shoot..

5- The USB (CA-45) ground when not connected to main Arduino board ground, then i get the erratic results on LCD display i.e. the steps start increasing although all the toggle switches in Auto mode.... but when i connect the USB ground to the Arduino board common ground the LCD display stablized, but do not shows COM:....

6- When i remove the USB from the computer side, this erratic behaviour on LCD start again....I think something is floating...

a) I am researching, some small mistake or some wrong components or some missing component...and also need all of your help including the great Walter... b) I am also looking forward of your suggestions why my RESET button do not work... Regards

I checked the voltages at Rx and Tx pins of at ATMEGA328P pins. With Rx-Gnd = 0.5V and with Tx-Gnd= 5V, The CA-45 cable Rx=0.1V and Tx=3.5V, Have i to change the resistor values between CA-45 Tx/Rx and Arduino Tx/Rx to get it work properly?

Wow.. got the problem solved for communication with ca-45 nokia data cable. I have to rewire the resistors actually made a small stripboard and wired the complete stuffi.e. Rx/Tx and Gnd.

previously i was using an extension cable between the Laptop and the USB hub of CA-45. This cable i think was culprit... Now i just connect the CA-45 cable directly to Laptop. you can see the Hyperterminal recognise the port, Arduino too recognise the port. I used Arduino Serial communication window to send MMMMMMMMMMMMMMMMMMM to Arduino and you can see the No. of Mmmmm display on LCD..

One wiered things the COM on LCD do not display the Port..But when i send M it display M...i.e. COM: M .... http://www.youtube.com/watch?v=qbfapWruLk8 All thing working fine except the above problem.

Regards

The reset button still not working..may be in later stage i\with help of you the problem may be resolved...

The reset button circuit looks OK on schematic - check the soldering perhaps?

Also from the photo it looks like you have missed out placing decoupling caps - they must be ceramic and very close to the 328. Without good decoupling you may get unreliable operation and strange behaviour.

Hi Mark, Thanks for your help and support... Following is the picture of sketch, what decoupling capacitor is missing and at what pin?

Regards