Guys, need some help.
I'm working on a project of a single channel pulse proportional thermostat. For those that may not know, I already have a four channel version which has been running in various versions since 2009 (the original never missed a beat in 5 years), so the original concept was to simply take a version of the 4 channel code and edit it to remove the references to channels 2,3, and 4, and after after a week or so I had a polished version of the code running on the EasyPIC5 development board. I left it running whils I drafted the schematic, produced a board layout and sent the gerbers off to China and received five of them back a week later. I built one of the boards and then tested it by using my bench top PSU built from a converted computer power supply - the board appeared to function OK - I got text on the LCD and so I removed the power and spent a day building the project in an ABS case and wiring it up (see attached).
On powering the device from a small switch mode power supply purchased from e-bay all I got on the LCD was DT to indicate it was in daytime mode, and a flashing asterisk that indicates the alarms are set. Resetting the PIC had no affect. Removed the PIC and tested it on the EP5 board - worked fine. So I spent a day messing about with power supplies from a standard linear regulator to another switch mode device - still no joy. One suggestion from a friend was that I need to make all unused pins outputs which I tried and still I had issues, so I thought it might be a grounding issue (the board doesn't have a ground plane) so I grounded all unused pins - still couldn't get it to work.
So I've just started again, with a fresh PIC - I've edited some code and now I'm getting less garbage on the LCD - and it's a little more stable ... but not usable. When it powers up now - it displays a splash screen stating the version of software loaded and then jumps to the main screen displaying the current temperature, DT or NT if the unit is in daytime or night time mode, flashing asterisk to indicate the alarms are on, and then on the second line, the set target temperature and current time from an RTC (ds1307). But this lasts for a variable length of time before the current temperature and time freeze but the flashing asterisk is still flashing. When the display of temperature and time become static the output to the heater is turned off, so at least the fail safe works. I have another 18F4620 running the same code on the easyPIC5 board, and reset both the unit and EP5 board at the same time. The PIC on the easyPIC5 board has been running for the past hour, but the one running in the unit lasted 11 minutes before the fault happened. I've also tried setting the time via the menu option and 3 out of 4 times the unit locked up, displaying 0:00: for the time ... I've reset the unit again, whilst I've been typing this post and we're up to 12 minutes and it's still running...
I've not posted the code here as it clearly works, and the failure seems to be at random periods...but would like to hear from anyone who has ideas on things to try in order to make this more stable
I'm working on a project of a single channel pulse proportional thermostat. For those that may not know, I already have a four channel version which has been running in various versions since 2009 (the original never missed a beat in 5 years), so the original concept was to simply take a version of the 4 channel code and edit it to remove the references to channels 2,3, and 4, and after after a week or so I had a polished version of the code running on the EasyPIC5 development board. I left it running whils I drafted the schematic, produced a board layout and sent the gerbers off to China and received five of them back a week later. I built one of the boards and then tested it by using my bench top PSU built from a converted computer power supply - the board appeared to function OK - I got text on the LCD and so I removed the power and spent a day building the project in an ABS case and wiring it up (see attached).
On powering the device from a small switch mode power supply purchased from e-bay all I got on the LCD was DT to indicate it was in daytime mode, and a flashing asterisk that indicates the alarms are set. Resetting the PIC had no affect. Removed the PIC and tested it on the EP5 board - worked fine. So I spent a day messing about with power supplies from a standard linear regulator to another switch mode device - still no joy. One suggestion from a friend was that I need to make all unused pins outputs which I tried and still I had issues, so I thought it might be a grounding issue (the board doesn't have a ground plane) so I grounded all unused pins - still couldn't get it to work.
So I've just started again, with a fresh PIC - I've edited some code and now I'm getting less garbage on the LCD - and it's a little more stable ... but not usable. When it powers up now - it displays a splash screen stating the version of software loaded and then jumps to the main screen displaying the current temperature, DT or NT if the unit is in daytime or night time mode, flashing asterisk to indicate the alarms are on, and then on the second line, the set target temperature and current time from an RTC (ds1307). But this lasts for a variable length of time before the current temperature and time freeze but the flashing asterisk is still flashing. When the display of temperature and time become static the output to the heater is turned off, so at least the fail safe works. I have another 18F4620 running the same code on the easyPIC5 board, and reset both the unit and EP5 board at the same time. The PIC on the easyPIC5 board has been running for the past hour, but the one running in the unit lasted 11 minutes before the fault happened. I've also tried setting the time via the menu option and 3 out of 4 times the unit locked up, displaying 0:00: for the time ... I've reset the unit again, whilst I've been typing this post and we're up to 12 minutes and it's still running...
I've not posted the code here as it clearly works, and the failure seems to be at random periods...but would like to hear from anyone who has ideas on things to try in order to make this more stable