COUNT is not counting again

[jellis00]

Bruce,
OK, I am using PBP compiler via MicroStudio that uses MSPM assembler. So I made the config change. Now I get a different, but single assembler error: " Error[118]: Overwriting previous address contents[2007]" When I click on it, it points to the @__config statement.
Again I don't know what this is telling me...can you advise.
BTW, is there anywhere that you can get error listings for the MSPM assembler so you know what they mean?

[mister_e]

http://www.picbasic.co.uk/forum/showthread.php?t=11116

[jellis00]

Thanks, Mister e, for the link. The article by Melanie on how to set configuration fuses answered my error question and also a lot of others I have had about the subject. I edited my .incl file per her instructions to eliminate overwrite by the @__config statement and it now compiles without errors.
Now that it finally runs, I have another question for Bruce. The Non-interrupt code runs fine, but I am not seening any pulse counts show up in TMR0 value when I write it during execute and then use READ in PICKkit2 to read the memory address....it is continuously zero. I thought maybe it was because my simulation mode for pulses wasn't working so I put a voltmeter on the RA2 pin while running the program and depressing the switch button to simulate pulses. What I saw was that RA2 was at 1.8 volts when the switch was open and of course it went to ground when I depress it. Isn't the 1.8 volt transition enough to trigger the TMR0 to count the pulses?

[jellis00]

Bruce, I see now in 16F690 data sheet that for TTL the minimum Vih threshold is 2.0 volts and for Schmidt trigger it is 0.8 volts. Would my switch grounding interface appear to RA2 as TTL or Schmidt trigger? Since the RA2 input is 1.8 v when open and I am grounding it to create a simulated pulse, I don't know whether this is enough downward transition or not. If not, what can I do about it. I thought the open circuit voltage level of RA2 would be over 2.0 volts.

[Bruce]

Do you see where it states TMR0 = 0 ' clear TMR0 count

This clears the timer0 count. If you need to write the timer0 count value to EEPROM first,
then simply move the TMR0 = 0 below where you have WRITE 7, TMR0. Then you will clear
the TMR0 count after you write it to EEPROM.

It's not rocket science...;o}

A TTL input requires 2V to VDD. As long as power is 4.5V ≤ VDD ≤ 5.5V, which just means
VDD is greater than or equal to 4.5V and less than or equal to 5.5V. Then it meets the Vih
logic 1 threshold.

A Schmitt Trigger tytpe input requires 0.8V * VDD to VDD.

If you were operating from a 5V supply, then 0.8 * 5V = 4V, which is what you'll need to
apply as a minimum to the input for it to recognize a logic 1.

Ground is ground. Your switch is for sure taking the input to ground.

With 4.5V ≤ VDD ≤ 5.5V, Vil is met when the input is at Vss, up to 0.8V. But check the
column under Conditions to be sure. It varies a bit with different VDD levels.

Look at PINOUT DESCRIPTION – PIC16F690. Now look at RA2 for what type of input T0CKI
is under the Input Type column.

Now look at RA5. When you use RA5 as a general purpose I/O-pin, it only needs TTL level
voltages. When you flip the switch to make it the Timer1 clock input, now it's a Schmitt
Trigger input.

Check out the BLOCK DIAGRAM OF RA5 to find out why.

It's all right there. Just takes time to learn how to find & decipher it all...;o}

And, when that doesn't work, download the latest Errata sheet for the PIC you're using.
Microchip screws up once in a while, and makes changes to datasheets....;o}

[jellis00]

Bruce, I moved the TMR0 = 0 clear statement after the WRITE statement. However, that is not the problem. I can see while running the code that the TMR0 value is never exceeding the value of K so it never enters the ELSE block and therefore never gets to the WRITE statement which leaves the EEPROM address at inital value of FF continuously.
All this is telling me that my approach to simulating the input pulses by momentarily grounding the RA2 port with my switch closure is not triggering the TMR0 count, but not quite sure what to do about that...I don't yet have access to the meter so I can use real pulse inputs from the sensor.
I understand what you are saying about the threshold value for Vih. However, my 16F690 is running off 5.0 volts, so I would have expected the voltage at RA2 to be near 5.0 volts when the switch is open (not grounded). Yet what I see is 1.8 volts, which is obviously not enough for Vih. This doesn't make sense to me, but explains why the TMR0 value is not incrementing. Any ideas why the RA2 port voltage would be at 1.8 vdc rather than 5.0 vdc when it is unloaded?
I also didn't quite understnd your comments about RA5. My code is a close modification of the Non-interrupt version code you posted above and doesn't even mention RA5 (see current code posting below). Are you saying I have to use RA5 somehow in generating the "clock" input to RA2??

@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
  K CON 15     ' Calibration factor for flow meter = # pulses per gal
  
' Setup Timer0 as an 8-bit counter with the clock input on RA2.
' 1:1 TMR0 prescaler
' TMR0 counts on high-to-low transitions
  OPTION_REG = %00111000
  
' A/D & Comparators disabled
  ANSEL=0           ' all digital
  ANSELH=0          ' analog module disabled
  CM1CON0=0
  CM2CON0=0
  
' Port setup
  PORTC = 0         ' LEDs off, PULSOUT RC3 provides a high-going pulse
  PORTA = 0
  TRISC = %11110000 ' lower 4 pins outputs
  TRISA = %11111111 ' RA2 = 2TMR0 clock input for simulated meter pulse inputs
  TMR0 = 0          ' clear TMR0 count       
  
Main:
  IF TMR0 < K  THEN
    ' Keep the valve open...do nothing..let water flow
    HIGH PORTC.0    ' Light LED continuously while water is flowing
  ELSE
    WRITE 7, TMR0   ' write before TMR0 cleared
    TMR0 = 0        ' clear TMR0 count
    Low PORTC.0     ' Blink LED on each clear after TMR0 >= K
    PAUSE 500
    HIGH PORTC.0    
    PAUSE 500
    LOW PORTC.0
    PULSOUT PORTC.3,1000  ' Generate required 10 msec pulse to RC3 
  ENDIF
  GOTO Main
  END

[jellis00]

Bruce, I may have stumbled onto part of my problem. I checked the switch interface more closely and discovered that the wire I was inserting into a female header that was connected to RA2 from the switch was not making good contact. Now when I check the voltage on RA2 pin when it is open output it reads 3.2 vdc. Still a long ways from VDD or Vih, but yet when I now depress the switch I am getting TMR0 count values. However, I notice that only 3-4 depressions of the switch causes TMR0 to obviously exceed the K value and trigger the ELSE block where it is written to memory and then cleared. I presume that this means there is a lot of switch bounce on the momentary switch depressions, each bounce being counted as a pulse by TMR0. Yet I can't figure out why it even works when the RA2 voltage transitions are only from 3.2 volts to ground. Any ideas?
Maybe Interrupts would still be the better approach to do the counting, where the interrupt would trigger on the first switch closure and should ignore the switch bounces while further interrupts are disabled during the Int-handler. What do you think?

[Archangel]

However, my 16F690 is running off 5.0 volts, so I would have expected the voltage at RA2 to be near 5.0 volts when the switch is open (not grounded). Yet what I see is 1.8 volts, which is obviously not enough for Vih. This doesn't make sense to me, but explains why the TMR0 value is not incrementing. Any ideas why the RA2 port voltage would be at 1.8 vdc rather than 5.0 vdc when it is unloaded?

RA2 is set as an input by the tris register, so the impeadence is relativly high, your meter MAY be enough load to reduce the voltage read, install a pull up resistor from RA2 to VDD to bring it up to the 5v level or enable WPUA (sect 4.3) data sheet.

[jellis00]

Joe, I enabled a WPUA.2 = 1 on RA2. However, with this change the voltage on RA2 when open circuit output is still at 3.2 vdc rather than Vih or close to Vdd. My code now looks like below. Interestingly the WRITE 7, TMR0 in the IF block never shows a value other than zero. However, just a couple of momentary switch activations will enter into the ELSE block where the WRITE 9, TRM0 statement shows a value of greater than K each time. So it looks like a lot of switch bounce going on, but the thing I don't understand is why the WRITE 7, TMR0 statement isn't showing any TMR0 values< K.
I also notice that if I comment out the LED blink statements in the IF block, the WRITE 7 statement doesn't write anything because the memory address shows a continuous FF value. Strange things that I don't understand. But at least it looks like the TMR0 is counting whether the value shows up correctly or not.
Tomorrow I am going to try to generate another method of simulating the external sensor input pulses to eliminate the switch bounce problem. I thought this might be possible by using one of the I/O pin outputs in a similar blink sequence loop as I am using for the LED, and then route that output into RA2. Do you think this would work? I will try to use one of the I/O pins that has a CMOS output.