12F683 - basic code not working

[Scampy]

Hi Guys,

Playing about with a 12F863 chip for a small project, but to start with thought I would do the basic LEDs flash to ensure programming and that the PIC runs. The code compiled, and ran, flashing the LED on RA0 (on the EasyPIC5 board, which corresponds to GPIO.0). I then added a simple "if then" statement so that if a switch was pressed taking GPIO.1 low the code would jump to the section to flash the LED. But when compiled and loaded to the chip the LED still continues to flash regardless if the switch is pressed or not. I've enabled the pull up on the development board which has no effect

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %11111110
ANSEL = 0   		
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:
If Switch1 = 0 then 
goto demo
else 
goto main

demo:
high Motor
pause 1000
low Motor
pause 1000
goto main
endif
Goto main

Any ideas why ?

[Scampy]

Interestingly this works

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %11111110
ANSEL = 0   		
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:
If Switch1 = 1 then 
gosub demo
endif 
goto main

demo:
high Motor
pause 1000
low Motor
pause 1000
goto main
REturn

[Acetronics2]

Hi, Malc

I would have written ...

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %00111110
ANSEL = 0           
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:

If !Switch1 then 

demo:
  high Motor
  pause 1000
  low Motor
  pause 1000
endif

goto main

but it's just me ...

at least, your "endif" should be placed just before the " demo " label ...

cause the " IF " condition never sees the " ENDIF " condition reset ....

tadaaaaaa ...

Alain

[AvionicsMaster1]

I'm assuming your using PBP3 and to do configs you need to do them like this and both "config" lines need to be in caps. I know PBP2.6 was different but with either version both "config" lines need to be in caps.

#CONFIG
;configuration directives in Assembly Language
#ENDCONFIG

TRISIO on the 12F683 is only 6 bits wide so I'm wondering if you need to change it to TRISIO = %111110. I think when you set the TRISIO and the GPIO as input and low respectively you'll always have a low at GPIO.0. When you set the pin low and told it to wait for a low it did what you told it to do. That is go to the demo subroutine. Since you changed it to =1 you had a state change and the chip could sense that. The reply by Acetronics2 did that by using the ! sign.

Your second take on the subroutine and endif look better.

As usual I'll await for someone to tell I'm wrong.

[Scampy]

I'm assuming your using PBP3 .

Sorry, wrong assumption - using 2.60

Quick question and slightly off topic, but related to this project... I'm using an H-bridge to control the motor as I need it to be bi-directional. I've been experimenting with some NPN and PNP transistors that I had in my hobby box, BC639 and BC640 and have had a small low current motor running from the PIC. However the actual motor I will be using is a 540 type with a 6:1 gearing. Even though it will be running from a 3v supply (separate to the 5v pic supply) my guess is that the current might be too high for the BC639 / 640 transistors. Can anyone advise if using these transistors would be OK for such a motor, or should I use something like the TIP220 transistors ??

[wdmagic]

I would use FET's, or a L298 chip. the 298 works great. the FET's i use are a bit overkill for what your doing but you can get lower values.
some that work well for all hobby motors from the old style that were in tape decks to modern RC racecars is
RFP12N10L
IRF540
IRF9530

[Scampy]

Following suggestions I've ordered a module from e-bay based on an L298N controller, which should work as under testing the 540 motor was drawing 0.7A and these things are rated at 2A.

I'm now working on the light detection side of the circuit. Basically the idea is to automatically open a door at dawn (wife now keeps chickens !). So when the light level reaches or exceeds a threshold, the motor runs, opening the door until the door hits a micro switch which then changes a pin status which then turns off the motor.

I've purchased a 16k-33K LDR from Maplin ( http://www.maplin.co.uk/p/16k-33k-oh...resistor-n57ay ) and connected that from the 5v line to GPIO.0 and covering the LDR makes the associated LED on my development board go out, and increase in brightness due to ambient light or when a bright torch is shon on the LDR. So the resistance is varying based on the light level, so far so good. Now the issue I'm having is that having set the ACD to 8 bits this should give me a 0 - 254 range of values... but in testing to get the motor to run at various values, these are not what I would expect.

Here's the test code:

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

' Hardware configuration
' ======================



TRISIO = %001111 
ADCON0 = %10000001 
ANSEL = %00110011 
DEFINE ADC_BITS 8
DEFINE ADC_SAMPLEUS 50 
CMCON0=7

Motor1 var GPIO.4
Motor2 var GPIO.5
ADChannel0 var word

GPIO = 0 ' clear all output
Pause 50 ' internal oscillator settle time

main:
low Motor1
low Motor2
adcin 0,adchannel0 ' Read AN0

If adchannel0 >2 then
  high Motor1
  Low Motor2
  pause 5000
low Motor1
low Motor2
endif

goto main

If I put in <1 for the argument, the motor runs even with the LDR covered. If I put in >1 the motor won't run unless I shine the torch directly on the LDR. I'm sitting here in ambient light with the sun shining in the window so the motor should be running.

Any ideas as to what I'm doing wrong ?

[Demon]

Do you use a word for 8 bit as well?

Motor2 is never going on by the way.

Robert

[Scampy]

OK corrected that (original example code must of been for higher resolution...) but still no joy in setting the thresholds

Motor two is always off in this example as its the other terminal to the H bridge

[aratti]

You should post the schematic of your project in order to get proper help. Very likely your problem is in the hardware arrangement.

Cheers

Al.

[Scampy]

Al,

The PIC is on an EasyPIC5 development board, but basically this is the schematic. I've also tried replacing the LDR with a 10k pot and whilst the LED on the dev board dims in brightness the threshold values still have the same effect. Placing the LDR between +5 and GPIO.0 gives a better range of brightness in the LED (not shown in the schematic) from off when the LDR is covered, to bright when an LED torch is placed directly over the LDR.

I don't program much, so often feel like a newbie when I dust off the development board, and ADC is something I've only once played with. As far as I can understand, the voltage on GPIO.0 should be converted into a byte value between 0 and 254, so I could set the threshold at which point GPIO.4 is made high ?

[Demon]

Shouldn't there be protective diodes "somewhere" whenever a motor is used?

I don't really get how that motor is wired. I would expect a pulse method, but the code is constant on for 5 seconds.

Admittedly confused.

Robert

[Scampy]

Robert,

I grabbed the h-bridge circuit from a web site, which using pnp / npn transistors works ok for the test motor (see above). I will be using an H-bridge chip for the larger motor.

Yes for testing I have the motor running for 5 sec once the threshold has been breached

[AvionicsMaster1]

I think you need a voltage divider network for the LDR. As it is the voltage on your ADC input line will always be 5VDC.

I also wonder about the capacity of your transistors. The stall current on the some of the motors I found was 46 Amps. If the motor were to stall, your transistors would burn out with unknown consequences. If you want to use this motor I'd put a fuse in the supply line to limit current during stalls.

Typically motors make alotta noise when running. I think it's a great idea to separate the power supplies. Just make sure to make the low side connected between the two systems.

My intimation of TRISIO is relevant to PBP2.6 also. I'm not sure if PBP starts with LSB when reading the TRISIO and quits after 6 bits or starts at the MSB and quits after 6 bits. I do know the 12F683 only has 5 I/O pins and one I only pin so your TRISIO statement should be 6 bits wide.

[Scampy]

Thanks for the comments:

I've tried using the LDR in series with a 10K pot between 5v and GND, connecting GPOI.0 to the junction between them and still can't get anything meaningful for the value of the variable that stores the ADC readings.

I've corrected the code thus:

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

' Hardware configuration
' ======================



TRISIO = %001111 
ADCON0 = %10000001 
ANSEL = %00110011 
DEFINE ADC_BITS 8
DEFINE ADC_SAMPLEUS 50 
CMCON0=7

Motor1 var GPIO.4
Motor2 var GPIO.5

ADChannel0 var byte

GPIO = 0 ' clear all output
Pause 50 ' internal oscillator settle time

main:
low Motor1
low Motor2
adcin 0,adchannel0 ' Read AN0

If adchannel0 >10 then
  high Motor1
  Low Motor2
pause 5000
low Motor1
low Motor2

endif


goto main

[aratti]

Check the risistence of your LDR in both condition (dark and light). Since the lowest resistance should be found in light, use this value for your devider network. In this way you should have a value in volts near to zero in dark and near to Vdd/2 in light, more than enough to be sure to trip the system at the right time.

By the way the schematics of your Hbridge is wrong! NPN should be connected on the low side, while PNP should be connected on the high side.

Follow the wise suggestion given above, always use freewheel diodes when using inductors!

Cheers

Al.

[Scampy]

Al,

My fault, I drew the schematic the wrong way round (I was rushing ). I've now placed diodes between the collector and emitters of each transistor as suggested.

Measuring the LDR I get a few hundred ohms when the torch is directly into the face of the LDR and around 2.1m ohms when I place my finger over it. Under the ambient light in the room it was averaging 16K - 18K. I've tried placing the LDR and an 18k resistor in series between +ve and GND and then connecting GPOI.0 to the junction between the two. The LED on the development board was lit quite bright and covering the LDR had no effect. I then used a 200 ohm resistor based on the fact that in light the resistance was a few hundred ohms when tested.

With the 200 ohm resistor in place as a voltage divider with the LDR, under normal room light with a value of adchannel0 >2 in the if then statement the motor runs. If I change that to adchannel0 >3 and re-compile the motor won't run regardless of bright light or darkness.

With the divider made up as the LDR between +5v and GPOI.0, and the 18K between GPIO.0 and GND I get 0.6v on GPIO.0 when the ldr is covered, and around 3.5v with the torch shone directly at the ldr. So I would assume this voltage range of 3v should be enough for the ADC to read ? so why is it that the ADC is acting more like a switch with a value of 1 rather than 255 steps ?

[aratti]

Add the following defines on top of your code:

DEFINE ADC_BITS 8
DEFINE ADC_CLOCK 2
DEFINE ADC_SAMPLEUS 50

Cheers

Al.

[Scampy]

Hi Al,

I've modded the code so I can see what's going on.

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %001111 
ADCON0 = %10000001 
ANSEL = %00110011 
DEFINE ADC_BITS 8
DEFINE ADC_SAMPLEUS 50 
DEFINE ADC_CLOCK 2
CMCON0=7


Tx              var GPIO.5         
ADChannel0 var byte

GPIO = 0 ' clear all output
Pause 50 ' internal oscillator settle time

main:
adcin 0,adchannel0 ' Read AN0
Serout2 Tx,84, ["val: ",#adchannel0,10]
pause 5000

goto main

The divider made up as the LDR between +5v and GPOI.0, and the 18K between GPIO.0 and GND.

Compiled the code and loaded it to the chip. Opening the serial tool in Micro-studio I get a value of 1 when the LRD is in ambient light or covered and 2 with the torch shone directly on it.

Ideas ??

[Scampy]

As a postscript, i wired a 10K pot between +5v and GND with the wiper to GPIO.0 and got the same results - seems the ADC isn't working

[Scampy]

OK I'm going to throw this thing out the window in a moment

I downloaded a sample code from this forum written by Bruce

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50
number VAR word

'CMCON = 7 ' Comparators off
ANSEL = %00000001 ' GPIO.0 A/D in, rest digital
ADCON0.7 = 1 ' Right justify for 10-bit
GPIO = %00000000 ' Initialize outputs
TRISIO = %00000001 ' GPIO.0 = input, rest outputs
Tx              var GPIO.5


main:
adcin 0,number ' Read AN0
Serout2 Tx,84, ["val: ",#number,10]
pause 5000
goto main

With the 10K pot wired between the supply with the wiper to GPIO.0 and get readings between 437 and 440 !!!!!!!!!!!!!! - still just three digits between min and max.
I had to rem out the CMCON line - presumably the 12F683 has no comparators, would that be the case.

[Archangel]

Hi Malcolm,
Comparator register for this chip is CMCON0 set CMCON0=7 to turn off as per data sheet 8.3
It compiles. You might have to set the CCP1CON to zero too , not sure about that though.

[HenrikOlsson]

Hi,
I haven't been following this thread but why do you say presumably the 12F683 has no comparators, would that be the case ?

Why not simply open the datasheet and have a look? Sure enough, the 12F683 DOES have a comparator and it's control register is CMCON0 - which you had got correct in your previous snippets of code but not in the latest one. I'm not saying this is the problem though.

Verify that ALL your grounds/commons are connected, as you move the wiper of the pot measure the voltage right at the PIC, between pins 8 (Vss) and 7 (AN0) to verify that it's not a loose connection or floating ground etc.

/Henrik.

[Scampy]

OK, I've removed the breadboard connection from the EasyPic5 and configured the board to use the 10K pot on the EasyPic5. I have the USB/Serial breakout board connected to +5v, GND and GPIO.5 and confirmed the communications were OK in the serial monitor window. I've added the correct setting for the comparators (must of removed the 0 at the end of the statement when editing the file- my bad ).

Loading the code I can get 0 - 1023 by moving the wiper on the EasyPic5 board, so the chip is reading 0-5v and converting that to a digital value.

I then added back the lines for the motor control, making them GPIO.2 and 4, and hooked up the H-Bridge on the breadboard - I added the trigger of 100 in the line "if number >100 then turn on the motor" and watched what happened when I turned the pot on the easyPic5 board and low and behold, when the value hit 101 the motor came on......

I'm going to pull all the connections off the breadboard and re-check the wiring - seems that the issue is external and not the code. One possible cause could be the resistance / capacitance nature of the breadboard causing the issue ??

Anyway, thanks guys for your comments and input.... as always it's nice to receive assistance and helps with the learning curve

Malcolm

[Scampy]

Hi again,

I'm stumped on what's happening when I run the following code, and having gone over it time and time again I might be overlooking the obvious.

I have a motor connected to the H-bridge module that arrived yesterday - making pins 1 high and 2 low makes the motor run one way and reversing which pin is high and low makes the motor run the opposite way. I'm using a separate 9v supply for the motor.

When first turned on, the threshold set means that the code is set to night mode. I then shine a light on the LDR and the motor runs until I connect GPIO.5 to 5v to simulate the door closing the micro-switch at the end of its travel. So far so good. However, if I remove the connection between GPIO.5 and +5v to simulate the door in the close state GPIO.5 remains latched high. Grounding the pin momentarily has no affect, and disconnecting the H-bridge has no affect. Only way to clear this is to turn off and on the EasyPic5 board.

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

DEFINE ADC_BITS 10              ' ADC resolution
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50
number VAR word                 ' Variable to store ADC result
day var byte                    ' Variable to indicate day or night

CMCON0=7
CCP1CON=0
ANSEL = %00000001               ' GPIO.0 A/D in, rest digital
ADCON0.7 = 1                    ' Right justify for 10-bit
GPIO = %00000000                ' Initialize outputs
TRISIO = %101011                ' GPIO 0,1,3,5 = input, 2 & 4 outputs


Motor1          var gpio.2      ' H-Bridge pin 1
Motor2          var gpio.4      ' H-Bridge pin 2
SW1             VAR gpio.5      ' Door open limit switch


low sw1                         ' Ensure limit switch is 0 (door is closed)
low Motor1                      ' Turn off H-Bridge pin 1
low Motor2                      ' Turn off H-Bridge pin 2
day=0                           ' Initialise unit to check if day time

main:
if sw1=0 then day = 0           ' If limit switch is open, and mode is night then
adcin 0,number                  ' Read AN0
if day=0 then                   ' Day 0 = night, Day 1 = Day
  If number >660 then           ' If ACD result is above a threshold
  low SW1                       ' Set state of limit switch to off
  high Motor1                   ' Turn on H-Bridge pin 1
  Low Motor2                    ' Turn off H-Bridge pin 2
endif
endif
if SW1 = 1 then                 ' Door closes limit switch and applies 5v to GPIO.5
  low Motor1                    ' Turn off H-Bridge pin 1 }  Stop motor
  low Motor2                    ' Turn off H-Bridge pin 2 }
  day = 1                       ' Set variable to day to indicate the door is open
endif

goto main

The logic behind this project is that when the light level increases at dawn past the threshold it drives the motor which by use of a threaded rod slides open the door on the coop. When the door closes a micro-switch at the end of the travel the power to the motor is turned off and the unit placed in day mode. At the end of the day a switch will be pressed directly applying 5v to pin2 of the H-Bridge thus reversing the motor, opening the door and opening the switch, changing its state from 1 to 0.

Any ideas ??

Malcolm

[HenrikOlsson]

Hi,
First you configure GPIO.5 as an input by setting the TRISIO.5=1 - OK, that's fine since you're going to be monitoring a switch connected to that pin.
Then you set up an alias so that SW1 accesses GPIO.5 - perfectly fine.
Then you go and do LOW SW1 - which turns the GPIO.5 into an output and pulls it low - not OK, the pin is no longer an input so it can't read the state of the switch.

Keep GPIO.5 as an input and make sure it has a pullup resistor to Vcc if the switch pulls it low or a pulldown resistor do Vss if the switch pulls it high.

/Henrik.

[Scampy]

Cheers Henrik,

I've removed all reference to SW1 =1 or LOW SW1 and it now no longer latches. - Thank you.

Now to actually turn this into a working door

[Scampy]

I've been playing about with the code and have now tested it on the development board over and over again, simulating the process of the door actuator being manually closed, and then opened triggered by the increasing light levels at dawn. Next step will be to transfer the PIC to a bit of strip board and add the regulators etc and then test it for real and monitor the current drawn to close the door on the coop. I plan on using a motorcycle battery 12v /4Ah which should be plenty. If funds permit I may add solar charging as a project at a later date.

Anyway, thanks guys for the assistance with this...

Malc

[AvionicsMaster1]

I did a project similar to this and had to account for something blocking door travel. I ended up with .1 ohm, I think, in series with the motor to monitor load by measuring the voltage across the resistor to determine current flow.

If motor is free running then current will be high initially but should be lower once friction and inertia are overcome. But if it's blocked/hampered/whatever the stall current will stay relatively high. I think I set it up to try to open and if blocked wait some time and then try again. Another ADC input if you've got a free port. Just a thought.

[Scampy]

Well that version of the project didn't work so well in the field...

I'm now working on a second version which uses a RTC. Basically I already have half the code written for one of my other projects so most of this will be a cut and paste. But something is really puzzling me and would welcome your advice.

I'm using a 16F690 (20 pin DIP) because it has both a basic UART and IC2 interface, and I happened to have a sample in my project box. I could be cleaver (yeah right) and use the full capabilities of the DS1307 and program the times for each month so it takes care of BST and GMT etc, but for now I thought the easiest way would be to use a serial utility to set the time and trigger value as required. Using PicMultiCalc to get the coms values I am able to connect and receive data, however the time is shown as 00:00 in the following code. Now like I mentioned , I've cut and pasted the section and same variables in a previous project so there should be no reason for it not to work. To prove the DS1307 is working on the breadboard (it hasn't been removed since I took a break from the previous project) I removed the 16F690 and replaced it with the 18F4580 and connected the jumper to the EasyPIC5 board - clock was displaying the time set by the code. Noted the correct clk and dta pins, powered down the EP5 board and mapped the connections to the pins used by the 16F690. Replaced the 16F690 and tested again - the serial monitor in Microcode Studio connected and displayed "Time : 00:00"

I've looked at the data sheet, but not sure if I am missing anything (probably some register needs setting but I'll be dammed if I can see it) so hopefully someone here might be able to assist.

Here's the code

'****************************************************************
'*  Name    : Chicken Coop Door Control                         *
'*  Author  : Malcolm Crabbe                                    *
'*  Date    : 30th January 2014                                 *
'*  Version : 1.0                                               *
'*  Notes   : Uses PBP 2.60c                                    *
'*          : 16F690, int osc 4MHz                              *
'*          : Program uses RTC  to turn                         *
'*          : on an electric motor and open a sliding door.     *
'*          : Door travel controlled by limit switches          *
'****************************************************************


ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF  
endasm

ANSEL=%00000000
ADCON1=7
ADCON0 = %00000000                      'AD converter module disabled
ADCON1 = %00001111 

TRISA=%00000011                         'set PORTA as all output 
TRISC=%00000001                         'set PORTC as all output apart from RC0
TRISB=%00000011

DEFINE HSER_RCSTA 90h                   'Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h                   'Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 25                    '9600 Baud @ 0.16%
DEFINE HSER_CLROERR 1                   'Clear overflow automatically

day             var byte 
RTCMin          var byte		        'RTC Minutes
RTCHour         var byte	            'RTC Hours
RTCsec          var byte                'RTC Seconds

TimeH           var byte                'variable to store Hours
TimeM           var byte                'variable to store Minutes
SS              VAR Byte                'variable to store Seconds

CounterA        var byte	            'General purpose Variable
CounterB        var byte	            'General purpose Variable

Counter1        var word                'used to store the current time as a digit.  Counts minutes from 0000 at midnight (to be added later)

Relay           var PortA.5             'used to activate relay and thus reverse direction
Motor           var PortA.4             'used to drive the motor
SW1             VAR PortA.0             'Door open limit switch
SW2             VAR PortA.1             'Door closed limit switch
Tx              var PortB.7             'used for sending time value in testing
Rx              Var PortB.5             'used for receiving time value in testing

SetMN           var byte		        'Used to set time Minutes
SetHR           var byte	            'Used to set time Hours
SetSS           var byte                'Used to set time Seconds 

RCIF            VAR PIR1.5              'USART receive flag
GIE             VAR INTCON.7
RCIF=1

SCLpin          var PORTB.6             'RTC pin - clk
SDApin          var PORTB.4             'RTC pin - data

setHR = 08                              'initial time to 8am 
setMN = 00

'convert initial time to BDC and write it to the DS1307
CounterA=SetMN
Gosub ConvertBCD
RTCMin=CounterB

CounterA=SetHR
Gosub ConvertBCD
RTCHour=CounterB

I2Cwrite SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour] 


test:

I2CREAD SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour]  ; read DS1307 chip

timeH=(RTCHour>>4)                        'convert the BCD format of the hours register and store in variable timeH
timeH=(timeH &$03)*10
timeH=timeH+(RTCHour&$0F)

timeM=(RTCMin>>4)                         'convert the BCD format of the mins register and store in variable timeM
timeM=(timeM &$07)*10
timeM=timeM+(RTCMin&$0F)    

ss=(RTCSec>>4)                            'convert the BCD format of the sec register and store in variable ss
ss=(ss &$07)*10
ss=ss+(RTCSec&$0F)                     

Counter1 = (TimeH *60)+ TimeM             'take hours and multiply it by 60 then add odd minutes to get the total minutes into counter1

Hserout["Time: ",#TimeH DIG 1,#TimeH DIG 0,":",#TimeM DIG 1,#TimeM DIG 0,10]
pause 1000


goto test



'*******************************************************************************
' convert BDC format to decimal
 ConvertBCD:
	CounterB=CounterA DIG 1                        ' CounterA is the entry variable
	CounterB=CounterB<<4                           ' CounterB holds the converted BCD result on exit
	CounterB=CounterB+CounterA DIG 0
	Return
'*******************************************************************************

[AvionicsMaster1]

Well, just the first part of the post I'm not sure what state you want ADCON1 set to. Initially you have it set to 7 then 15. That one extra bit appears to significantly effect your ADC conversion cycle.

I also think you need to set OSCCON and put a DEFINE OSC ? in your code. I know the default is 4MHz but isn't the RC oscillator in your config the low low frequency oscillator? Could be wrong about that without reading further.

TRISA is only 6 ports and I think PBP starts with the LSB so you'll have bits 0 and 1 as input. TRISB doesn't look to have RB0 to RB3 so only 4 bits needed to set as output. TRISIC is indeed 8 bits but you've got TRISIC.0 set to input not as described in comments.

I don't often do serial so you'll have to let someone else chime in. I didn't look at rest of code. Hopefully I'm correct on at least one of these items and it will solve your problem.

[Scampy]

Thanks for the assistance

I've just sat down with a large mug of coffee and some toast and run through the datasheet... I think I've covered most things (I still find these datasheets a struggle, but hopefully picking things up). I've set the registers as follows (with comments), and the code compiles

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF  
endasm

DEFINE  OSC 4
DEFINE HSER_RCSTA 90h                   'Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h                   'Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 25                    '9600 Baud @ 0.16%
DEFINE HSER_CLROERR 1                   'Clear overflow automatically

ANSEL  = %00000000                      'Set all pins digital
ANSELH = %00000000                      'Set all pins digital
ADCON0 = %00000000                      'AD converter module disabled
OSCCON = %01100101                      'bit7 not used, bits 6-4 4mhz default, bit3 int osc, bit2 HS stable (ignored - at 4Mhz), bit1 not stable, bit0 int osc used for system clk 
CCP1CON= %00000000                      'Turn off CCP module
SSPCON = %00001011                      'Ic2 master

TRISA=%00000011                         'set PORTA as all output apart from RA0 and RA1( bits 7&8 unimplimented read as 0)
TRISB=%11110000                         'set PORTB as all input ( bits 0-3 unimplimented read as 0)
TRISC=%11111111                         'set PORTC as all input (default for POR)

Having compiled and loaded the code, pleased to say it all works now !!

OK I might of gone overboard on configuring registers, but at least it's helped me get some understanding with the datasheets.

[HenrikOlsson]

Hi,
Glad you've got it going! Just a quick note: The I2CREAD/I2CWRITE commands does not use the (M)SSP module in the PIC. You're enabling the (M)SSP module for I2C mode so I'm actually a bit surprised that it works because I thought that when enabled it (the (M)SSP module) takes control over the I/O-pins - I'm obviously mistaken there.

However, the PBP I2C commands are bitbanged, they don't use the I2C hardware in the PIC so there's no need to enable the hardware for it. It might lead to problems.

/Henrik.

[Scampy]

Thanks Henrik,

So I can remove the SSPCON line ?

[HenrikOlsson]

Yes, according to the datasheet the POR default of the SSPCON register is 0. Looking at the register definition it shows that as long as bit 5 is 0 the SSP module is disabled and its pins functions as normal I/O. This is probably also why it works the way you currently have it - you do have it configured for I2C mode but it's not actually enabled since bit 5 is cleared. Had you enabled it I don't think the I2C commands would've worked since the SSP module then would've been in control of the pins.

/Henrik.

[Scampy]

Guys,

I've been resting my code using a DC motor driven by a simple transistor circuit as per attached which works well, with the intention of using a double pole change over relay to switch the polarity to the motor (throw off from my old model railway days as that's how we used to make the loco go backwards or forwards). The think is I can't get my head round how to use the transistor to turn the power on / off.

I came up with the attached, but not sure if this would work, or if I should have the transistor between the relay and GND (ie C to relay, E to GND). I've left the Diode out as the motor is bi-directional

Advice welcome before I blow up a handful of transistors trying

[pedja089]

I use this for motor driver:

[Scampy]

Thanks you..

[HenrikOlsson]

Hi,
Regarding your first schematic, generally you need to put the transistor on the low side. Otherwise you need a higher voltage on the base than you've got on the collector. Put the relay "on top", then on to the motor and finally the transistor at the bottom, emitter to ground. Yes, the motor is biderectional but the current thru the transistor is always the same so put the diode back across is, cathode facing "up" of course.

/Henrik.

[Scampy]

Quick questions guys, I've been developing the hardware further and need to swap the 2930 transistor for something more powerful for driving the 540 type motor. I have a TIP126 PNP darlington, which works, but with reverse logic on the base. IE instead of turning on when the base is high it's high when the pic pin is low. I could change the code so that the output is constantly high and goes low when the conditions are met, but was wondering if there was a simple way of making the transistor fire with a positive voltage on its base ?