Help with realtime clock and timer

[Darrel Taylor]

Very funny!!!

No, he's using the internal oscillator, with a 32768 crystal on Timer1 for a RTC.
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[Bruce]

Hi Darrel,

Haven't gone over the whole schematic - it's pretty cramped & incredibly hard to follow on-screen, but, outside a few things already mentioned, RA4 is an O.C. output attempting to drive an NPN.

I have no clue what's being controlled with those AC line switches, but I definitely would NOT connect any mains to my DC rails. What happens when one is turned on? With neutral tied to +5Vout and the other AC leg coming right through an AC switched load into the DC rails - it kinda looks like an accident waiting to happen to me...;o}

I may be wrong. I've never used one of those AC switches, but seems kinda adventurous to me.

Whole bunch of discreet resistors, pots, etc all with the same part reference #'s, 15-ohm LED limiting resistors (ouch), yada yada.

I would have to print that one out, and use various colored markers to run it all of it down.

Looks like a valiant effort, but looks like it may need a little tweaking before flippin the ON switch..}

[geselaw]

Hi Darrel

All the LED limiting resistors are 150 ohm(typing error).The VDD connection to the phototransistor was corrected and I have posted the new schematic "Scrolling_2" above.About the MCLR though, I thought by disabling it with "@ device mclr_off", I turned it to be a digital input. That is why I tied it to 7805 output so that it would tell the PIC when the main power is off (go to low_power mode to conserve battery energy). I also used (R1)10kohm as a pull down resistor on RA5 so that RA5 would not float when the main power is off. Does it make sense ?

Hi Bruce

The ACS108 is used for controlling 110v solenoid.I completely agree with you about using the ACS switch.In the nest version ,opto-isolated solid state really will be used.I have not paid attention to RA4. Thank you for pointing that it is an open drain output. I really need to drive that NPN. I don't know how but either I have to use RA4 with a pull up resistor or use RA2 as in my configuration (VRCON.6 =0) I have not used this port for any thing else. A close examination shows that this pin was configured as digital input (TRISA= %10100110). So I think this might be another problem in my program as this pin could have floated at any time.The problem with RA2 is that it says in the datasheet "The RA2 pin can be used as a simple D/A output with limited drive capability. Due to the limited drive capability, a buffer must be used in conjunction with the Voltage Reference output for external connections to VREF. "

I really need your advise which way to go.

Best Regards
geselaw

[Darrel Taylor]

>> "@ device mclr_off"

OOPS, my fault. I should have seen that. Doh!

For the RA4 thing. You could use a PNP transistor between +5V and the relay. Or use a PNP to drive the NPN, but that adds another part.
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[geselaw]

Thanks Darrel, I will try it out ASAP.

[mister_e]

if i can suggest one thing.. i really love to use ULNXXX serie chip. you have 7 built-in transistor resistor and diode. Really handy, save a lot of wiring and parts AND at the end reduce the Bill of material. ULN2003 and how much other are really great.