Hi all,
I just made my first homebrew 2 layer PCB and things didn't work as expected.
I tried to shrink an already working circuit of mine which utilizes a 2x16 lcd which is driven by a PCF8574 and I2C. The mcu used is 16F88 on 4mhz. So, first time everything went ok. Then my board did not work and all I was seing was garbage in my LCD. Then it worked again. Then it stopped again..and so on. I thought it might be a timing problem since i used a new HD44780 so i switched to my old LCD to verify it. Nothing happend. I've been desoldering and resoldering my board the last 2 days, trying to find what is wrong, but I can't find it. I've increased all my delay routines and went up to 50ms for sending data and chars to the LCD but I get no difference. I thint that noise is the cause but i can't explaing it since my board will work after 10-15 resets and the same code and circuit works 100% in a one layer PCB. Are there any guidelines about investigating the cause? I found that the PCF returned a wrong output so I decided to change it but nothing. Some times it works properly and sometime i doesn't and is driving me crazy.
I just made my first homebrew 2 layer PCB and things didn't work as expected.
I tried to shrink an already working circuit of mine which utilizes a 2x16 lcd which is driven by a PCF8574 and I2C. The mcu used is 16F88 on 4mhz. So, first time everything went ok. Then my board did not work and all I was seing was garbage in my LCD. Then it worked again. Then it stopped again..and so on. I thought it might be a timing problem since i used a new HD44780 so i switched to my old LCD to verify it. Nothing happend. I've been desoldering and resoldering my board the last 2 days, trying to find what is wrong, but I can't find it. I've increased all my delay routines and went up to 50ms for sending data and chars to the LCD but I get no difference. I thint that noise is the cause but i can't explaing it since my board will work after 10-15 resets and the same code and circuit works 100% in a one layer PCB. Are there any guidelines about investigating the cause? I found that the PCF returned a wrong output so I decided to change it but nothing. Some times it works properly and sometime i doesn't and is driving me crazy.