Q: using MCLR for Input on 12F683

[johnnylynx]

Thanks LinkMTech and Mackrackit:

Both worked. FYI, I fly RC planes and have recently gained interest in the PIC stuff, mostly with the 12F683 due to its size. I'm learning this stuff...slowly (but wow, has it got potential!).

I have a couple more questions hopefully you can help me with.

1. having some issues simply running LED's on ports other than gpio.0 and 1. I'm not sure if I need to assign them, change them??? When trying, I see they have a faint glow???

2. When using GPIO.4 and an input to store a pulsin value, the program works, but if I use GPIO.3 it doesn't. I can't figure that one out.

Thanks again gents.

John.

[BrianT]

I crashed my RC aircraft using the PULSOUT command.

PULSOUT is a 'toggle'. Whatever state the pin was in, it will flip for the duration specified in the PULSOUT command. That is bad news if your servo pin gets clobbered and you were expecting it to be low when you called the PULSOUT routine.

To be safe, you MUST predefine the pin state before calling PULSOUT.

e.g.

LOW ServoPin
PULSOUT ServoPin, 500

will work every time.

HTH
Brian

[johnnylynx]

I crashed my RC aircraft using the PULSOUT command.

PULSOUT is a 'toggle'. Whatever state the pin was in, it will flip for the duration specified in the PULSOUT command. That is bad news if your servo pin gets clobbered and you were expecting it to be low when you called the PULSOUT routine.

To be safe, you MUST predefine the pin state before calling PULSOUT.

e.g.

LOW ServoPin
PULSOUT ServoPin, 500

will work every time.

HTH
Brian

Thanks Brian, I've got the pulsout working...actual pretty good now. Just some issues with getting gpio.2 and gpio.3 to simply operate LED's!

My code is posted above.

Cheers,

John.

[mackrackit]

Thanks LinkMTech and Mackrackit:

Both worked. FYI, I fly RC planes and have recently gained interest in the PIC stuff, mostly with the 12F683 due to its size. I'm learning this stuff...slowly (but wow, has it got potential!).

I have a couple more questions hopefully you can help me with.

1. having some issues simply running LED's on ports other than gpio.0 and 1. I'm not sure if I need to assign them, change them??? When trying, I see they have a faint glow???

2. When using GPIO.4 and an input to store a pulsin value, the program works, but if I use GPIO.3 it doesn't. I can't figure that one out.

Thanks again gents.

John.

Can you post your code?

[johnnylynx]

Whoops, sorry about that!

here's the code:


oSCCON = %01100000 ' Ocs set to 4 MHz
TRISIO = %00000000 ' Set all ports to outputs, in this example
CMCON0 = 7 ' Analog comparators off
ANSEL = 0 ' Analog select set to digital, pg 69 data
ADCON0 = 0 ' A/D turned OFF, pg 68 of data
input gpio.4

inpulse VAR Word
memory var word
low gpio.4
low gpio.3


start:


SEROUT 0, 2, [12]
start2:
PULSIN 1, 1, inpulse

if inpulse<50 then
read 5, memory
serout 0,2,[12,17, "Activating",13,"Failsafe :", #memory*10]
goto start2
else
endif

if gpio.4=1 then
write 5, inpulse
serout 0,2,[12,17,"Failsafe",13,"Stored :", #inpulse*10]
high gpio.3
low gpio.4
else
low gpio.3
endif

SEROUT 0, 2, [17,22,#inpulse*10]
PAUSE 20


GOTO start

END

[Archangel]

OSCCON = %01100000 ' Ocs set to 4 MHz
TRISIO = %00000000 ' Set all ports to outputs, in this example
CMCON0 = 7 ' Analog comparators off
ANSEL = 0 ' Analog select set to digital, pg 69 data
ADCON0 = 0 ' A/D turned OFF, pg 68 of data
input gpio.4 '<font color=red> make input</font color>

inpulse VAR Word
memory var word
low gpio.4 <font color = red> ' Now you make it an output</font color>
low gpio.3


start:


SEROUT 0, 2, [12]
start2:
PULSIN 1, 1, inpulse

if inpulse<50 then
read 5, memory
serout 0,2,[12,17, "Activating",13,"Failsafe :", #memory*10]
goto start2
else
endif

if gpio.4=1 then '<font color=red> still an output, are you wanting an input?</font color>
write 5, inpulse
serout 0,2,[12,17,"Failsafe",13,"Stored :", #inpulse*10]
high gpio.3
low gpio.4 '<font color=red> is and should be an output</font color>
else
low gpio.3
endif

SEROUT 0, 2, [17,22,#inpulse*10]
PAUSE 20


GOTO start

END

[johnnylynx]

Thanks Joe,

I didn't catch that, I'll make changes and see if that fixes the input problem.

I still have the output issue though with GPIO.3, it doesn't want to run the LED.

Any thoughts?

John.

[mackrackit]

Not sure but I think that pin is input only.

[Archangel]

I dunno John, I never use the High / Low convention, preferring to specify TRISIO AND GPIO instead because as I understand it , High/Low reads modify's and writes the whole port ( all the I/Os ) when you do.