HI, I am using LPC 2387 controller and interfaced GSM module, Ethernet, 8 relays to switch AC load, smoke detector, vibration sensor and three input switches in this i am facing some problems as i have seen this it shows unexpected values on LCD Display, so i check for noise spikes in power supply so i am getting it over their but after adding Filter and capacitors it still their even we have used transistor to switch relays....... please help me to solve this ........... i have used 16by 2 lcd. some times it shows proper characters on display but after some time it shows any random data. i have checked all the soldering points on PCB and i also have catch diode across relay.

 

hi i have just started to design embedded system based circuits its my first design that i am doing it on LPC 2387 Arm Controller. i want to built my demo board which will have LPC2387, GSM sim900, Ethernet, 8 Relays triggered with transistor, RS 232, I2C, and Display 16by 2 LCD and IO's. so i dont understand how to start. i have designed Clock Circuit and reset circuit. Mainly i have doubt with

1> Power Section and Filtering
2> IO section
3> Different interfacing

 

Do you have suppression diodes across the relay coils? Like in the following diagram?

 

Do you have suppression diodes across the relay coils? Like in the following diagram?

ya we are having diode across relay

 

here i have attach one pic showing how we are connecting relays to switch output or AC. Please any one can tell me is is right way to use it or do i need some changes. one more thing is in my mind that if i am not using any IO pin of LPC 2387 then what should i do Leave it as it is without connecting it neither with the VCC nor with the GND or should i add pull up or pull down resistor on that pin.

 

i have used 16by 2 lcd. some times it shows proper characters on display but after some time it shows any random data.

How random? Are the bad characters always in the same place? Always the same bad characters? Or is it an occasiona changed character previosly written and just changed for no reason?

It would probably be best if you publish the entire schematic all at once instead of little pieces.

Some photos of the build may also help.

 

Thank you all finally we solved our problem problem was in serial connector that was faulty.

 

Thank you all finally we solved our problem problem was in serial connector that was faulty.

Thanks for letting us know the final outcome!