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'[PIC]: PIC16F84A + Ampire AC162B Rev E LCD (KS0066'
2001\05\22@234225 by Dylan

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Problem Description:
------------------------------
* I cannot get charecters to show on my LCD Screen.
* Im not sure if my circuit is correct in terms of an external clock for
the PIC.
* I have tried nearly every circuit diagram i have found on the net and the
matching software, which is for the hitachi controllers none of which seem
to work.

Parts List:
---------------

- PIC16F84A Microcontroller.
- Ampire AC162B Revision E.  16x2 Backlit LCD screen
   -> LCD Driver IC is a samsung KS0066U.
- 4.0 Mhz Crystal
- 2x 33pF Ceramic Capacitors
- 470 Ohm Resistor.
- LED

Circuit Description:
---------------------------

PIC RB(0-7) Pins are connected to LCD (DB0-7)   Pins.
PIC RA(0-2) Pins are connected to LCD RS, R/W, E Pins.
PIC Vss grounded.
PIC Vdd  ===> 5v Powersource.
LCD Pin1 ===> Grounded.
LCD Pin2 ===> 5v Powersource.
LCD Pin3 ==> 10Kpot for contrast
PIC RA3 => 470 Ohm Resistor => Red LED => Grounded.
PIC RA4 => 470 Ohm Resistor => Red LED => Grounded.
PIC OSCI => Leg 1 of 4.0Mhz Crystal => 33pF Capacitor1 = > Ground.
PIC OSCO => Leg 2 of 4.0Mhz Crystal => 33pF Capacitor2 = > Ground.

Questions:
----------------
1)  Is the KS0066U LCD driver compatible with the Hitachi driver for a
simmilar 16x2 LCD ?

2) Do you connect the ceramic capacitors between the OSC pins of the PIC
and the 4.0Mhz crystal or between the 4.0Mhz crystal and ground. I have
seen pictures on websites where the caps are connected between POC OSC pins
and the Crystal, whereas the PIC datasheet shows it connected between the
Crystal and Ground ?

3) I dont have access to an oscillascope and im not sure if the crystal is
actually working, or if the PIC is actually running so i connected a
resistor to RA4 to and LED, and added code to my program to light up the
LED if the LCD is busy and it didnt come on at all. I then cut out all my
LCD code and just put in code to turn PORTA HI->LOW to see if it would
light up the led and it didnt. I checked the pins of the PIC with a
multimeter, some were 5v, some were 0, but my port A wasnt changing as i
would have hoped.

4) Is there an easy way of checking things are all working without having
to spend hours wiring up a test circuit?

5) Has anyone managed to get an Apire LCD to display anything, if so do you
have a circuit diagram that i could look at?

6) Is there any ticky things i have to keep in mind when writing my
software and controlling the Samsung KS0066U LCD driver?





Dylan.

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2001\05\22@235928 by michael brown

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----- Original Message -----
From: "Dylan" <spam_OUTdylanTakeThisOuTspamFAST.FUJITSU.COM.AU>
To: <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
Sent: Tuesday, May 22, 2001 10:33 PM
Subject: [PIC]: PIC16F84A + Ampire AC162B Rev E LCD (KS0066U Driver) Wont
Work?


> Problem Description:
> ------------------------------
> * I cannot get charecters to show on my LCD Screen.
> * Im not sure if my circuit is correct in terms of an external clock for
> the PIC.
> * I have tried nearly every circuit diagram i have found on the net and
the
{Quote hidden}

How is the 10K pot hooked up?

> PIC RA3 => 470 Ohm Resistor => Red LED => Grounded.
> PIC RA4 => 470 Ohm Resistor => Red LED => Grounded.

You can't do this.  RA4 is open collector, meaning it can't source current.

> PIC OSCI => Leg 1 of 4.0Mhz Crystal => 33pF Capacitor1 = > Ground.
> PIC OSCO => Leg 2 of 4.0Mhz Crystal => 33pF Capacitor2 = > Ground.

What about /MCLR?  Make sure to tie it to Vdd.

>
> Questions:
> ----------------
> 1)  Is the KS0066U LCD driver compatible with the Hitachi driver for a
> simmilar 16x2 LCD ?
>
> 2) Do you connect the ceramic capacitors between the OSC pins of the PIC
> and the 4.0Mhz crystal or between the 4.0Mhz crystal and ground. I have
> seen pictures on websites where the caps are connected between POC OSC
pins
> and the Crystal, whereas the PIC datasheet shows it connected between the
> Crystal and Ground ?

The datasheet is the correct way.  It looks like you have it wired
correctly.

>
> 3) I dont have access to an oscillascope and im not sure if the crystal is
> actually working, or if the PIC is actually running so i connected a
> resistor to RA4 to and LED, and added code to my program to light up the
> LED if the LCD is busy and it didnt come on at all. I then cut out all my

See above comment about open collector output.  Turn the LED around and use
Vdd instead of ground.  BCF PORTA,4 will turn it on and BSF PORTA,4 will
turn it off.

> LCD code and just put in code to turn PORTA HI->LOW to see if it would
> light up the led and it didnt. I checked the pins of the PIC with a
> multimeter, some were 5v, some were 0, but my port A wasnt changing as i
> would have hoped.
>
> 4) Is there an easy way of checking things are all working without having
> to spend hours wiring up a test circuit?

A frequency counter to see if the clock is running.  An oscilloscope would
really be handy; beg, borrow or steal one.

>
> 5) Has anyone managed to get an Apire LCD to display anything, if so do
you
{Quote hidden}

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2001\05\23@003419 by David VanHorn

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>
>1)  Is the KS0066U LCD driver compatible with the Hitachi driver for a
>simmilar 16x2 LCD ?

That may be a fatal problem.

>2) Do you connect the ceramic capacitors between the OSC pins of the PIC
>and the 4.0Mhz crystal or between the 4.0Mhz crystal and ground. I have
>seen pictures on websites where the caps are connected between POC OSC pins
>and the Crystal, whereas the PIC datasheet shows it connected between the
>Crystal and Ground ?

www.dvanhorn.org/Micros/All/Crystals.php
Short version, caps go from the xtal pins (or the xtal pins on the chip) to
the chip's ground pin.
Not some other ground point.


>6) Is there any ticky things i have to keep in mind when writing my
>software and controlling the Samsung KS0066U LCD driver?

The init phase of the Hitachi chips is VERY picky.
Do one thing slightly wrong, and nothing happens. :(

When in doubt, add delays.
You can't get in trouble adding a few extra uS between operations, but get
it slightly too fast, and you're in trouble.  It's a variation of the "Rope
Rule".. Ropes come in two lengths only. Too long, and too short.
I can fix "too long". :)


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2001\05\23@003945 by Dylan

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>How is the 10K pot hooked up?

The Pots hooked up middle pin to LCD Pin for Vee (3), one pin to Vss, the
other to Vdd. Contrast works fine, LCD powers up as i can see faint blocks
when i tweak the Pot.


> > PIC RA3 => 470 Ohm Resistor => Red LED => Grounded.
> > PIC RA4 => 470 Ohm Resistor => Red LED => Grounded.
>
>You can't do this.  RA4 is open collector, meaning it can't source current.

LOL.. that would explain it.

> > PIC OSCI => Leg 1 of 4.0Mhz Crystal => 33pF Capacitor1 = > Ground.
> > PIC OSCO => Leg 2 of 4.0Mhz Crystal => 33pF Capacitor2 = > Ground.
>
>What about /MCLR?  Make sure to tie it to Vdd.

Yeah, i forgot to mention that pin, it is infact connected to +5V (Vdd).
Could i put a small button here to reset the PIC?

>The datasheet is the correct way.  It looks like you have it wired
>correctly.

Ok, sounds like im on the right path..

> > 3) I dont have access to an oscillascope and im not sure if the crystal is
> > actually working, or if the PIC is actually running so i connected a
> > resistor to RA4 to and LED, and added code to my program to light up the
> > LED if the LCD is busy and it didnt come on at all. I then cut out all my
>
>See above comment about open collector output.  Turn the LED around and use
>Vdd instead of ground.  BCF PORTA,4 will turn it on and BSF PORTA,4 will
>turn it off.

Thats a mighty fine idea, i will try that tonight.
So being an Open collector it can take in current but not put out.
You mentioned setting and clearing bits of port A... this is ofcourse with
pic PortA pins RA3->4
set to input with the using TRIS register?

> > 4) Is there an easy way of checking things are all working without having
> > to spend hours wiring up a test circuit?
>
>A frequency counter to see if the clock is running.  An oscilloscope would
>really be handy; beg, borrow or steal one.

That could mean a day trip to my uni to use their equipment.... i wonder if
you can hire them.. hrmm..

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2001\05\23@005328 by Dylan
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>>1)  Is the KS0066U LCD driver compatible with the Hitachi driver for a
>>simmilar 16x2 LCD ?
>
>That may be a fatal problem.

I have only seen two types of LCD Drivers on common LCD panels, and that is
either the Hitachi, or what i have on mine, a samsung. What others are
available.


{Quote hidden}

I have only one power supply and one ground, connect everything that needs
grounding to the -side of the power supply, everything that needs +5v to
the +side of the power supply.  My power supply is a home brew rectifier,
could it be that because there is a delay between when i actually plug the
supply in (because of the electrolytic capacitors i use) and when the pic
gets fully powered up that the initialisation of the LCD Driver dies?


>>6) Is there any ticky things i have to keep in mind when writing my
>>software and controlling the Samsung KS0066U LCD driver?
>
>The init phase of the Hitachi chips is VERY picky.

Aparently the samsung ones that i have do all that stuff themselves with
the busy flag set, then clearing it when its all ready for its first command.


>Do one thing slightly wrong, and nothing happens. :(

Strange that lots of people claim to have theirs work first time,
especially when connecting it to LPT ports for MP3 based projects. I have
been trying to fix this for weeks with no success. I started with LPT ports
and writing my own C program, and thought it more reliable to use fixed
timing of a PIC, and thats where i am now still with no luck.

>When in doubt, add delays.

I will keep this in mind when updating my software.

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2001\05\23@021236 by David VanHorn

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>
>I have only one power supply and one ground, connect everything that needs
>grounding to the -side of the power supply, everything that needs +5v to
>the +side of the power supply.  My power supply is a home brew rectifier,
>could it be that because there is a delay between when i actually plug the
>supply in (because of the electrolytic capacitors i use) and when the pic
>gets fully powered up that the initialisation of the LCD Driver dies?

You should tie the xtal caps to the pic's ground pin.
Homebrew power supplies can cause trouble too, if the voltage isn't within
spec ALL the time during operation. Of course all power supplies ramp up,
but once you're there, you should stay there all the time.
Another place where even a cheap scope will help a lot.


>Strange that lots of people claim to have theirs work first time,
>especially when connecting it to LPT ports for MP3 based projects. I have
>been trying to fix this for weeks with no success. I started with LPT ports
>and writing my own C program, and thought it more reliable to use fixed
>timing of a PIC, and thats where i am now still with no luck.

The delays of doing it on a PC may be a key factor there.
I rather doubt you can get the I/O lines to move as fast as in a
microcontroller.

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inability of sysadmins at TELOCITY to differentiate a signature line from
the text of an email, I am forbidden to have it.

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2001\05\23@022154 by Kashif Ali

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Mr. Dylan.

First of all remove PF capictors from crystal 4 Mhz and then check the lcd
work.

If still lcd does'nt work tell me I can give you the complete routines for lcd
"HD44780" which is compatible of Hatachi.

Kashif ali

Dylan wrote:

{Quote hidden}

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2001\05\23@022615 by David VanHorn

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At 11:20 AM 5/23/01 -0700, Kashif Ali wrote:
>Mr. Dylan.
>
>First of all remove PF capictors from crystal 4 Mhz and then check the lcd
>work.

Now why would you tell him to do that?

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2001\05\23@062742 by michael brown

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----- Original Message -----
From: "Dylan" <dylanspamKILLspamFAST.FUJITSU.COM.AU>
To: <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU>
Sent: Tuesday, May 22, 2001 11:19 PM
Subject: Re: [PIC]: PIC16F84A + Ampire AC162B Rev E LCD (KS0066U Driver)
Wont Work?


> >How is the 10K pot hooked up?
>
> The Pots hooked up middle pin to LCD Pin for Vee (3), one pin to Vss, the
> other to Vdd. Contrast works fine, LCD powers up as i can see faint blocks
> when i tweak the Pot.

That sounds pretty good.  The Hitachi types power up with dark blocks on the
first line.  If you are only getting faint blocks then possibly this Samsung
type may need to be pulled below Vss (-voltage) to obtain best contrast.
But if you get faint blocks you should still be able to see faint characters
when it is working.

>
>
> > > PIC RA3 => 470 Ohm Resistor => Red LED => Grounded.
> > > PIC RA4 => 470 Ohm Resistor => Red LED => Grounded.
> >
> >You can't do this.  RA4 is open collector, meaning it can't source
current.
{Quote hidden}

You would have to pull /MCLR up with a pullup and use a button to pull it to
ground to do the reset

>
> >The datasheet is the correct way.  It looks like you have it wired
> >correctly.
>
> Ok, sounds like im on the right path..
>
> > > 3) I dont have access to an oscillascope and im not sure if the
crystal is
> > > actually working, or if the PIC is actually running so i connected a
> > > resistor to RA4 to and LED, and added code to my program to light up
the
> > > LED if the LCD is busy and it didnt come on at all. I then cut out all
my
> >
> >See above comment about open collector output.  Turn the LED around and
use
> >Vdd instead of ground.  BCF PORTA,4 will turn it on and BSF PORTA,4 will
> >turn it off.
>
> Thats a mighty fine idea, i will try that tonight.
> So being an Open collector it can take in current but not put out.
> You mentioned setting and clearing bits of port A... this is ofcourse with
> pic PortA pins RA3->4
> set to input with the using TRIS register?

No, they should still be set to output using the TRIS.  Writing a zero to an
output pin pulls it to ground.  Writing to an input pin does nothing
usefull. (in this case)

>
> > > 4) Is there an easy way of checking things are all working without
having
> > > to spend hours wiring up a test circuit?
> >
> >A frequency counter to see if the clock is running.  An oscilloscope
would
> >really be handy; beg, borrow or steal one.
>
> That could mean a day trip to my uni to use their equipment.... i wonder
if
> you can hire them.. hrmm..
>
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> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>

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2001\05\23@064046 by michael brown

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> >
> >I have only one power supply and one ground, connect everything that
needs
> >grounding to the -side of the power supply, everything that needs +5v to
> >the +side of the power supply.  My power supply is a home brew rectifier,
> >could it be that because there is a delay between when i actually plug
the
> >supply in (because of the electrolytic capacitors i use) and when the pic
> >gets fully powered up that the initialisation of the LCD Driver dies?

I want to see the code.

>
> You should tie the xtal caps to the pic's ground pin.

Dave,
I didn't know this could be a problem.  I kind of figured that at four Mhz,
the wavelength is so long that unless my ground was more than about 50 feet
away from the pics ground that it couldn't hurt.  Why does it need to be
hooked so close to the pic's ground pin?

> Homebrew power supplies can cause trouble too, if the voltage isn't within
> spec ALL the time during operation. Of course all power supplies ramp up,
> but once you're there, you should stay there all the time.
> Another place where even a cheap scope will help a lot.

When I am testing, I keep the power supply on all the time and just use a
clip lead to hook it to the pic circuit.  Instant ramp up.  I haven't hurt
anything yet. ;-)

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2001\05\23@074306 by Dylan Hillier

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I have seen the LIGHT!!!!!!!!!!!!!!!!!!!! !  See below...

> > >See above comment about open collector output.  Turn the LED around and
>use
> > >Vdd instead of ground.  BCF PORTA,4 will turn it on and BSF PORTA,4 will
> > >turn it off.
> >
> > Thats a mighty fine idea, i will try that tonight.
> > So being an Open collector it can take in current but not put out.
> > You mentioned setting and clearing bits of port A... this is ofcourse with
> > pic PortA pins RA3->4
> > set to input with the using TRIS register?
>
>No, they should still be set to output using the TRIS.  Writing a zero to an
>output pin pulls it to ground.  Writing to an input pin does nothing
>usefull. (in this case)

Ok, turned the LED around, added a 470 Ohm resistor, programmed the pic
with the following code:


LIST P=16F84A, F=INHX8M
        __CONFIG _CP_OFF & _WDT_OFF & _XT_OSC

#include <d:\programs\mplab\p16f84a.inc>

BUSY_BYTE       EQU     0x0F

START
        CALL    SELECT_BANK1_RFM        <-- this just selects as it says
Bank 1 of the RFM.

        MOVLW   0x00    ; RB0-7
        MOVWF   TRISA

        CALL    SELECT_BANK0_RFM
START_LP
        CLRF    LCD_CTRL                ; Port A
        CALL    Delay
        CALL    Delay
        CALL    Delay
        MOVLW   0xFF
        MOVWF   LCD_CTRL        ; Port A
        CALL    Delay
        CALL    Delay
        CALL    Delay
        CALL    Delay

        GOTO    START_LP


Delay
    clrwdt
    movlw d'255'
    movwf    BUSY_BYTE
loop
    decfsz    BUSY_BYTE,F
    goto    loop
    return

END



The Result is:

My Red LED is flasshing away prominantly on my prototype board.



IMPORTANT THINGS I HAVE DISCOVERED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- The LED does NOT flash as smoothly as it probably should on and off. I
figure its got something to do with the fact the time delays are very short.

-HOWEVER, if i move my board around a bit it seems to change the speed of
the LED flashing ??????? So perhaps my wires arent soldered on correctly or
there is a huge amount of interference from the crystal on the wires causin
th epic to run erratically ?

- My wires are probably too thick for use with IC's, i have seen some
circuits wired up with nice looking thin wires apposed to my thick wire
strand covered in thick plastic covering. Which is better, thick or thin
for this application.

- This erratic behavour of my prototype board and pic would without a doubt
stuff up my attempts to correctly control the Samsung LCD driver... bummer.


Can anyone else think of things that cause this type of erratic, fast
flashing, slow flashing to occur or the pic to run at variable speeds?

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2001\05\23@090306 by Dylan Hillier

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For those of you watching this thread, there was talk about grounding pins
earlier.

I found some good information (although not directly related to PIC's) on
grounding and decoupline capacitors at the following URL:

http://mechsys2.me.berkeley.edu/ME235/LabFiles/index.html


Very interesting indeed.

Enjoy..

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2001\05\23@124448 by David VanHorn

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>
> > You should tie the xtal caps to the pic's ground pin.
>
>Dave,
>I didn't know this could be a problem.  I kind of figured that at four Mhz,
>the wavelength is so long that unless my ground was more than about 50 feet
>away from the pics ground that it couldn't hurt.  Why does it need to be
>hooked so close to the pic's ground pin?

It's not a wavelength thing.
First, it's not nice to radiate tons of EMI.
Second, if you make that ground return path longer than it needs to be,
then any EMI that it intercepts can affect your crystal operation.
When you're prototyping, you already have enough problems, no?


>When I am testing, I keep the power supply on all the time and just use a
>clip lead to hook it to the pic circuit.  Instant ramp up.  I haven't hurt
>anything yet. ;-)

No, and I wouldn't expect damage.  However, a non-monotonic rise can leave
you with the CPU or peripherals in a non-recoverable confused state, till
power goes away again.
As before, you already have enough problems.
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2001\05\23@124646 by David VanHorn

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At 11:07 PM 5/23/01 +1000, Dylan Hillier wrote:
>For those of you watching this thread, there was talk about grounding pins
>earlier.
>
>I found some good information (although not directly related to PIC's) on
>grounding and decoupline capacitors at the following URL:
>
>http://mechsys2.me.berkeley.edu/ME235/LabFiles/index.html
>
>Very interesting indeed.


I didn't see anything specifically on grounding, but there is a lot of good
info here.

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2001\05\23@131401 by michael brown

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----- Original Message -----
From: "David VanHorn" <EraseMEdvanhornspam_OUTspamTakeThisOuTCEDAR.NET>
To: <PICLISTspamspam_OUTMITVMA.MIT.EDU>
Sent: Wednesday, May 23, 2001 11:43 AM
Subject: Re: [PIC]: PIC16F84A + Ampire AC162B Rev E LCD (KS0066U Driver)
Wont Work?


> >
> > > You should tie the xtal caps to the pic's ground pin.
> >
> >Dave,
> >I didn't know this could be a problem.  I kind of figured that at four
Mhz,
> >the wavelength is so long that unless my ground was more than about 50
feet
> >away from the pics ground that it couldn't hurt.  Why does it need to be
> >hooked so close to the pic's ground pin?
>
> It's not a wavelength thing.
> First, it's not nice to radiate tons of EMI.
> Second, if you make that ground return path longer than it needs to be,
> then any EMI that it intercepts can affect your crystal operation.
> When you're prototyping, you already have enough problems, no?

OK, I see.  I wonder why they put the Vss pin on the other side of the chip
then.  How long is too long? 1cm? 1inch?  Or, just make it as short as
possible?

>
>
> >When I am testing, I keep the power supply on all the time and just use a
> >clip lead to hook it to the pic circuit.  Instant ramp up.  I haven't
hurt
> >anything yet. ;-)
>
> No, and I wouldn't expect damage.  However, a non-monotonic rise can leave
> you with the CPU or peripherals in a non-recoverable confused state, till
> power goes away again.
> As before, you already have enough problems.

I probably should have been more clear.  The circuit has a regulator with a
big cap on the output.

{Quote hidden}

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2001\05\23@145849 by David VanHorn

flavicon
face
>
>OK, I see.  I wonder why they put the Vss pin on the other side of the chip
>then.  How long is too long? 1cm? 1inch?  Or, just make it as short as
>possible?

The practice that I follow, is that this track gets #1 priority to get to
the CPU ground.
The components are placed as close to the chip as practical.
I don't allow any other "ground" connection to the caps, or ground lead of
a resonator.


>I probably should have been more clear.  The circuit has a regulator with a
>big cap on the output.

That's probably monotonic then.
Another gotcha is rise time.
The on-chip brownout detectors often have a spec for minimum risetime.
Too much C, and the chip isn't guaranteed to wake up.
Isn't it fun?
:)


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2001\05\23@194255 by Dylan

flavicon
face
>First of all remove PF capictors from crystal 4 Mhz and then check the lcd
>work.

What will this do to the waveform that the crystal produces?
I believe MicroChip recommends the capacitors because it helps to produce a
nicer sine wave for the pic to run off.

>If still lcd does'nt work tell me I can give you the complete routines for lcd
>"HD44780" which is compatible of Hatachi.

I would still like to see your routines, specifically writing to the LCD.

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2001\05\24@042005 by Alan B. Pearce

face picon face
>I probably should have been more clear.  The circuit has a regulator with a
>big cap on the output.

How big a cap? Part of your problem may be that the cap is too big, and
because the regulator goes into current limit the rise time becomes too
slow. I would say that a cap of 10 to 100uF would be heaps.

The other gotcha that you should be aware of is when disconnecting the
power. 7800 series regulators do not like having volts on the output, and no
volts on the input. Other regulators also have this problem. If you have a
capacitor on the output that will hold up the voltage for a significant time
after input power is removed it pays to put a diode across the output to
input of the regulator (reverse biased in normal operation) so the input is
never less than 0.6V below the output.

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