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I'm using a 16f616 and an lcd 24x2 display. Prior to hooking up the lcd I had been able to get the current draw down to a few uA's in sleep mode, but when I hooked up the lcd I was unable to get the current below 1.5 mA in sleep mode. I have disconnected the lcd during sleep, but the pic is still using 1.5 mA. Is there a command that will shut down the lcd and/ or the associated pins during sleep?
Hi kduck,
How about not turning the LCD on until you actually need it? Set a pin on the PIC as an output and it turns on a transistor that can then supply the power needed by the LCD. Also remember to setup a short time delay for the LCD to stabilize before sending data to it.
BobK
Perhaps tri-stating the pins connected to the LCD would reduce the sleep mode current draw.
It would be nice to see your code but absent of that are you setting an output pin high to get the LCD to sleep? That would keep your current usage high even with the LCD disconnected.
Normal disclaimer, I could be drinking Rudolphs flying juice also.
I will try setting the output pins high, that might do the trick.
I realized that I had, long ago, soldered a pot to the back of the lcd to control the contrast. Removing that and setting the pins controlling the lcd to high prior to the sleep command got me down to about 0.5mA. I also found that pulling the ground connection to the lcd dropped the current down to about 0.03uA… sounds odd, but that's the truth. So I used a spare pin to provide a ground to both the contrast and lcd ground connectin upon waking, and set it high prior to sleeping. Works great.
Thanks’ to both of you for the help.