Resetting a PIC

[Andrew Cowan]

Hi.

I have a Phanderson LCD controller on a Wulfden PCB, and for one of my programs, it must be reset half way through, or it does not work.

I would like to do this through my PIC (28X) - can I connect the reset pin of the LCD controller PIC to a 28X output, then say low 0 to make it reset?

What about the 4.7K pull up? Please let me know what the best way to reset this is - Thanks

Andrew

 

[Technical]

Yes, no harm to leave the 4k7 there.
Naturally you wlll have to make sure the PICAXE program takes the output high at the start of the program.

 

[Andrew Cowan]

Thanks technical.

Andrew

 

[kevrus]

I must ask, why does the lcd controller need a reset?

 

[Andrew Cowan]

The screen keept going weird, showing a couple of Ns, and needing a reset.

I have fixed it now - I found it was caused by the pin floating - high 7 after serouts stops the problem.

 

[kevrus]

I havn't used PH Andersons chip or the Wulfden board but ive never had that problem with the rev-Ed serial firmware chip on my own serial piggy-back board

 

[westaust55]

Resetting LCD module PIC

Andrew,

It seems a little strange that you need to issue a reset for the LCD PIC controller, unless you are issue an “illegal” command that is confusing the LCD controller.
You indicate that you are getting wrong numbers on the LCD screen.
Have you tried the command
?f - this will clear the LCD and leave cursor at home position.

Can you post you program and advise which specific PH Anderson controller that you have?
Is it LCD #107/117, 108 or 118 ?
Someone may be able to identify any problems with wrong commands to the LCD module.

I have fixed it now - I found it was caused by the pin floating - high 7 after serouts stops the problem.

Floating would suggest that your PIC module has a Open Collector transistor. Again seems a little strange that it works for a while. Would a pull up resistor on the line to the LCD module help?

 

[Andrew Cowan]

It seems a little strange that you need to issue a reset for the LCD PIC controller, unless you are issue an “illegal” command that is confusing the LCD controller.

It only happened when I tried to change the backlight bightness - not with any other commands.

You indicate that you are getting wrong numbers on the LCD screen.
Have you tried the command
?f - this will clear the LCD and leave cursor at home position.

After sending serout 7,T2400,("?B00") then pause 1000 to the display, it would turn off the backlight, show either NO or NOO or NNNN on the screen, then not respond to more commands until reset (although it did respond to other backlight commands.)

Changing the code to serout 7,T2400,("?B00") then high 7 then pause 1000 fixes this problem.

Can you post you program and advise which specific PH Anderson controller that you have?
Is it LCD #107/117, 108 or 118 ?
Someone may be able to identify any problems with wrong commands to the LCD module.

It is the 118 Chip.

Floating would suggest that your PIC module has a Open Collector transistor. Again seems a little strange that it works for a while. Would a pull up resistor on the line to the LCD module help?

I have not had the backlight command working with PHandersons LCD on this PCB before (without high 7). I have had the PHAnderson LCD + backlight working on other PCBs, and I have both the PHAnderson LCD and the Rev Ed LCD working off this circuit board without backlight.

It is on long wires - mayby this is messing it up. Anyway, high 7 after each serout fixes the problem.

Andrew