Power up problem with PIC16F1824

[nobner]

Hello together,
i have a problem with powering up a PIC16F1824.
When I apply 5V, the port RA5 gets high for 1µs.
Power Supply is fine, no interruptions - 100n directly on controller supply pin's.
On the port I have connected a FET (resistor 1K from port to gate, 47k from gate to gnd)
I defined port as output in tris register.
Power up timer is enabled.
In a former thread i read, that port and lat settings must be done before tris setting - so
I did this, but the 1µs pulse is still there.
I tried lata and porta - no difference.
I would be thankful for any idea.
best regards
norbert

[longpole001]

you do not say if the fet is PCh or N ch , but have you tried clearing the port after after assigning the TRIS register . It be helpfull if you included the area of code that you use to configthe chip , assuming its not changed on the fly in other parts of the code

this for the PIC 16F1825 , so should be trhe same for your pic

' config for 16F1825

    #CONFIG
;----- CONFIG1 Options --------------------------------------------------
    __config _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_ON & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_ON

;----- CONFIG2 Options --------------------------------------------------
    __config _CONFIG2, _WRT_OFF & _PLLEN_ON & _STVREN_ON & _BORV_HI & _LVP_OFF
    #ENDCONFIG

 

 '----------- 16F1825  - PIC chip settings --------------------

    OSCCON   = $70          ' Select 32Mhz , internal clock  ( 8Mhz when conf2 - PLLEN_OFF)
                            ' Bit 7 0 = 4xPLL disabled  1= 4xPLL enables ( overrided by conf word 2 setting -  PLLEN)
                            ' bits6-3 -  1111 = 16Mhz , 1110 = 8MHz or 32Mhz ( depends on 4xPLL - conf word 2)  1101 = 4 MHz, 1100 = 2MHz 1011 = 1MHz
                            ' bitS 0-1 - 00= Clock set by Conf word ,01 = Timer1 OSC , 1x = internal Osc Block

    APFCON0 = %00000000	    ' All Default - No change when using SPI  use SDO1 = RC2 , bit6=0
    APFCON1 = %00000000	    ' All Default  APFCON1 = %00000000



    CM1CON0 = $00 	        ' Disable / Clear comparator 1
    CM1CON1 = $00 	        ' Used with CM1CON0
    CM2CON0 = $00 	        ' Disable / Clear comparator 2
    CM2CON1 = $00 	        ' Used with CM2CON0
    CMOUT   = $00           ' Disable Comparitors output register - used only if comparitor on

    ANSELA =  %00000000     ' Set Port A - Digital I/O  , 0 = Digital  1 = Analog
    ANSELC =  %00000000     ' Set Port C - Digital I/O  , 0 = Digital  1 = Analog

    INLVLA = %00000000	    ' Set Port A to TTL Levels 0 = TTL , 1 = SCHMITT TRIGGER - Used port reads and Interupt on Change
    INLVLC = %00000000	    ' Set Port C to TTL Levels 0 = TTL , 1 = SCHMITT TRIGGER - Used port reads and Interupt on Change
    SRCON0 = %00000000      ' Disable Latched Outputs
    SRCON1 = %00000000      ' Used with SRCON0 register

    ADCON0 =  $00           ' Disable A/D
    ADCON1 =  $00           ' Disable A/D  - used with ADCON0 settings

    WPUA   = %00001000	    '  Port A - Turn off week Pullups 1=ON , for each port ( globle enable set in option_reg.7)set wpu on PortA.3 as input only - ref spec
    WPUC   = %00000000      '  Port C - Turn off week Pullups 1=ON   For each port

    DACCON0 = $00           ' Disable D/A
    DACCON1 = $00           ' Disable D/A - used with DACCON0
    FVRCON  = $00           ' Disable Fixed Voltage Ref


    OPTION_REG.7 = 1       ' Weak Pullups disabled  1 = globel disable 0 = globel enable ( set by each port - WPUA & WPUC settings)
    OPTION_REG.6 = 0       ' Interupt on Falling Edge of INT pin  0= falling edge  1= rising edge
    OPTION_REG.5 = 0       ' TMR0 clock source - 1=T0clk pin 0=internal clock
    OPTION_REG.4 = 0       ' TMR0 0=L/H of TOCKI pin  1=H/L of TOCKI pin
    OPTION_REG.3 = 0       ' Use Prescaller for TMR0  0= Yes , 1 = No
    OPTION_REG.2 = 1       ' Timer0 prescaler Rate Select bits 2-0(set to 1:256)
    OPTION_REG.1 = 1       ' 000 = 1:2  , 001= 1:4  , 010 = 1:8   , 011 = 1:16
    OPTION_REG.0 = 1       ' 100 = 1:32 , 101 = 1:64, 110 = 1:128 , 111 = 1:256

    T1CON  = %01110100     ' Timer 1 ,bit7-6 = TMR1 CLK source 00 = Instuction Clk(Fosc/4),01 =sys clk,10=ext clk,11=cap sense osc
                           ' bit5-4 = TMR1 prescale 11= 1:8 ,bit3=0 LP off,bit2=1 no sync ext CLK ,bit1= 0 n/a,Bit0=0 Timer 1 on/off
    T1GCON = %00000000     ' Timer 1 Gate Control bit7 0= counts regardless of gate 1 = gates in use  , bit6 gate active when 1= High  ,0=low
                           ' bit5 0= toggle mode diabled 1= enabled  bit4 single pulse mode 1- en 0= dis, bit 2 -status bit,1-0 - gate source sel

    T2CON  = %01110011     ' Timer 2 off + 1:15 postscale ,1:64 prescale ( bit 7 = x, bit6-3 1110 = 1:15 postscale, bit2=0 timer off ,bit1-0 = prescale 10 = 16 , 11= prescale 64
    T4CON  = %00000000	   ' POSTSCALER 1/1,STOP,PRESCALER 1/1
    T6CON  = %00000000 	   ' POSTSCALER 1/1,STOP,PRESCALER 1/1

    TMR0 = 0               ' Clear TMR0 MODULE REGISTER

    TMR1H = 0              ' CLEAR TMR1H MODULE REGISTER
    TMR1L = 0              ' CLEAR TMR1L MODULE REGISTER

    TMR2 = 0		       ' CLEAR TMR2 MODULE REGISTER
    TMR4 = 0			   ' CLEAR TMR4 MODULE REGISTER
    TMR6 = 0		       ' CLEAR TMR6 MODULE REGISTER

 'PR2 = 255              ' Timer 2 Preload value
 'PR4 = 255              ' Timer 4 Preload value
 'PR6 = 255              ' Timer 6 Preload value

  
    TRISA = %00001000  ' setup Port A input=1,output=0 for I/O pins ( Note RA3 - input only - refer spec)
    TRISC = %00000000  ' setup Port C input=1,output=0 for I/O pins
    PORTA = %00000000  ' clear 
    PORTC = %00000000  ' clear

[peterdeco1]

Just throwing in my 2 cents, I had the same problem with a 16F819. I forget the port pin involved but it was connected to a piezo buzzer. Everytime the PIC was powered up it would cause a chirp in the buzzer. Turning off the power-up timer cured the problem.