How to detect low battery in battery powered F683 circuit

[mark_s]

Your battery positive will be connected thru a 1K resistor to the adc, you may need a divider if v battery is greater than VDD? Then you take a normal acin reading and determine what number between 0 - 1024
equals a low battery. If an < x then low_bat. else..

To start

Fixed voltage reference FVR page 137

ADCIN will take care of the ADCON0 register

FVRCON = %10000001 ' vref enabled 1.024v
ADCON1 = %11110011 'Right just,FRC,+vref connected to FVR

[tekart]

FVRCON = %10000001 ' vref enabled 1.024v
ADCON1 = %11110011 'Right just,FRC,+vref connected to FVR

Mark, thanks for the very helpful configuration settings. I got a test chip working fine using 8-bit reads and left justified results. I am in a similar position to peterdeco1 in that I have a circuit board designed for production and ready to go into volume assembly. Fortunately I already had two resistors connected to the A/D input creating a voltage divider so I am good to go - except for one minor problem. My test code works on the F683 chip just fine but when I try to implement it on my actual design I find that I do not have proper digital I/O on PortA.5 for some reason. My design uses portA.0 for the analog input and portA.2 for PWM out. I am struggling with what configuration error I have that is preventing portA.5 from operating as a digital output. I have been poring over the datasheet for an hour or so now and can't seem to find a configuration that seems to be setting that into something other than digital I/O. Any help would be appreciated.

[mark_s]

These "enhanced" pics don't use the GPIO like the old ones. Use porta.5 to read
and lata.5 to write. See page 13 and page 121 of the data sheet


Add: See Hecklers code and configs
http://www.picbasic.co.uk/forum/show...ght=pic12f1822

[tekart]

Wow. Thanks Mark - I missed that. I just HATE all these whiz bang "features" that force us mere mortal coders to spend *days* learning a new chip! Grrrr. <end rant>
SO to implement a pin as output only I use:
GreenLED var lata.1 ' high = light power LED
and also set:
' config
TRISa = %011001 ' set I/O directions (0 = output, 1 = input)
LATa = %011001

- still not getting it to work with above settings. Do I have bit polarity right for LATA?

[mark_s]

I think you would declare your variable as

GreenLED var PORTA.1

[tekart]

I think you would declare your variable as
GreenLED var PORTA.1

Been testing that and the compiler seems to accept either
GreenLED var PORTA.1
or
GreenLED var LATA.1

[mark_s]

At this point without posting your complete code it's hard to guess what's wrong.