3 replies to this topic

[Coding Smackdown]

I recently have been putting together a replacement controller for an Electric Turkey Fryer. I had everything working just perfectly with all of the circuits on a breadboard and had even brewed 5 batch of beer with the entire setup. I had created two circuit boards to put in an enclosure with the Netduino, one was a shield that held all of the power conversion, relay driver and button connections, the other was a daughter board that attaches to a 16 x 2 LCD Display using the same circuit in Simon's post over at http://geekswithblog...id_crystal.aspx I sent the board out to BatchPCB.com to be made and finally got them back. I spent a couple days assembling the boards and when I went to test everything my LCD Display is not working. At first I thought maybe my connector from the shield to the daughter board was messed up, but I checked it and I have connectivity to everything as expected along with +5V and Ground. What I am not seeing is +5V at the LCD Display, I'm only seeing +1.8V. At first I thought there was a short some place, but I cannot find anything wrong. I went back to re-wiring the daughter board on the breadboard and now I'm getting the same results coming off the shield. It looks as if the signals to drive the 595 chip are not coming across. The connector I'm using is about 6 inches in length, which was about the same length as the jumpers I used when originally wired up the circuit. What I'm seeing now is a bunch of garbage on the display and a lot of strange flashing and the back light going on and off as the Netduino sends data to the display. I've attached pictures of the schematics and pc boards for you to take a look at in hopes someone can spot my issue. The boards are double sided with the red traces on the top and the blue traces on the bottom. Hopefully someone can point me in the right direction. Thanks

Attached Files

•  Main_Board_Schematic.png   36.67KB   60 downloads
•  Main_Shield_Board.png   64.03KB   82 downloads
•  LCD_Display_Schematic.png   23.17KB   59 downloads
•  LCD_Display Board.png   32.81KB   34 downloads

[nakchak]

Do you get 5v between pin 16 and 8 on your led driver chip? And 5v between pin 5 and 1 of your connector on the led board?

Update
Just had a closer look at your schematic vs pcb layout, what happens if you connect the gnd pin on the netduino on your pin 1 of your LCD connector?

I may be reading the tracks on the PCB wrong, but im not seeing a connection to ground, on the schematic i see a net called GND but none of the gnd pins on the netduino are connected, so the 5v circuit is effectively floating?

If it works with a connection to the ND GND then at least the fix will be simple on your board, just solder a length of wire from the GND pin on the shield header to pin one of your LCD header and your GND net will be completed.

Must say i am interested in your project, currently thinking of building something similiar for my father's micro brewery, currently use's a large burco water heater for the mash, which i modified to have a bypass switch on the "safety" thermal switch which prevents it reaching a boil (sold as boiler but for safety/litigation protection reasons it cant actually be sold able to boil and instead stops heating at ~90c).

Edited by nakchak, 22 June 2012 - 10:02 PM.

[nakchak]

Pressed wrong button i am a fool

[Mario Vernari]

Two diodes (D2 and D4) of the rectifying bridge are reversed. Being them reversed, if you plug the AC all of the diodes could be melted. I don't understand the role of the transistor T1. More in general, how the supplies (+12V and +5V) is flowing. As Nakchak pointed out, the Netduino is completely floating: no ground, nor +5V. Finally, I mean that's a typo, but you used to label as +3.3V the supply actually at +5V in the LCD section. Cheers