my project Capacitive Sensing LED dimmer 12F1822 via PWM

[Heckler]

Just wondering if anybody has taken the time to bread board up the circuit and see how it works?

If you do build the circuit I suggest you lower the value of the Resistor in the Zener ckt to around 4700 ohms.
(Assuming you are trying to drive it with 12 Volts)

I still need to learn about how to best design a small circuit board with an included touch pad. I still am unsure if I need a surrounding ground to make the touch sense work better.

My testing shows that it does not seem to make much difference.


Here is a link to a video of my circuit working

(the video is in my drop box so I am not sure how this will work, its about 8 meg)

https://dl.dropboxusercontent.com/u/...LED_dimmer.m4v

[Aussie Barry]

Hi Dwight,

Are you looking to make these Camping/Emergency lights as a commercial venture or just for your own use?
If it is the latter, you would probably be best served (from a purist aspect) to throw a bit more coin at an LDO voltage regulator.

From my own curiosity standpoint, what have you used for the capacitive touch sensor in your prototype and how do you plan to implement the sensor in your production unit?

Cheers
Barry
VK2XBP

[RWright]

Hello!
I'm new here, but I like your capacitive touch program example. The only difference I would like to be able to do is have 3 touch pads, one for brightness up, brightness down, and one for on/off. I just wonder where
I would put the code that would scan the three cps inputs, would it be in the main program area, or in the interrupt itself? I'm also driving 5 leds that indicate what brightness I am at. Currently, I have the scan code in the main program area, and the determination of which switch is pressed in the interrupt portion. However, I keep having problems with the touch working intermittently. Can you see where I am having problems?
I am using a PIC16LF722A for the micro.


'************************************************* ***************
'* Notes : Copyright (c) 2016 *
'* : Editor MicroCode Studio Plus PBP 3.0.6.0 *
'* : LS1236-A Startrol Touch Controller *
'* : MUST BUILD PROJECT WITH MPASM ASSEMBLER *
'* : Device = 16LF722A-I/SO *
'* Version : 1y.0 *
'* Name : LS1236_1y.BAS *
'* Author : R. WRIGHT *
'* : *
'************************************************* ***************

'SET CONFIGURATION FOR INTERNAL OSCILLATOR WITH PLL MULTIPLIER ON
#CONFIG
__config _CONFIG1, _INTRC_OSC_NOCLKOUT & _WDTE_OFF & _BOR_OFF & _PLLEN_ON
#ENDCONFIG


define OSC 4


INCLUDE "DT_INTS-14.bas" ' PBP interrupt routines (MUST BE IN SAME FOLDER)
INCLUDE "ReEnterPBP.bas" ' Include if using PBP interrupts
' Courtesy of Derryl Taylor, PBP Wizard!

OSCCON = %00010000 'SETS INT OSC TO 4Mhz
ANSELB = %00000111 'SETS INPUTS B0-B2 AS ANALOG
TRISB = %00000111 'SETS INPUTS B0-B2 AS INPUTS
WPUB = %00000000 'DISABLES WEAK PULL-UP BITS
'TRISC = %00001000 'SETS INPUT C3 AS INPUT

OPTION_REG = %10000111
'1 = All weak pull-ups are disabled (except MCLR, if it is enabled)
' 0 = Interrupt on falling edge of RB0/INT pin
' 0 = Timer0 clock is internal cycle clock (Fosc/4)
' 0 = Increment on low-to-high transition on RA4/T0CKI pin
' 0 = Prescaler is assigned to the Timer0 module
' 111 = 1:256 Timer0 prescaler rate

T1CON = %11000001 'enable timer 1 (bit 0) & source the clock from the CPS module (bit 6 & 7 =11)
'set the CPS module highest frequency availabe (for vcc mode) + timer0 clock sourced from CPS module. (BIT 1)


CPSCON0 = %10001100 '1 = CPS module is enabled
' 000 = unused
' 11 = Oscillator is in High Range. Charge/Discharge Current is nominally 18 µA
' 0 = Capacitive Sensing Oscillator Status bit (only readable)
' 0 = Timer0 clock source is controlled by the core/Timer0 module and is FOSC/4

CPSCON1 = %00000001 '0001 = channel 1, (CPS1)


' Software variables

CPSX_PRESENT var WORD 'VARIABLE FOR BUTTON CURRENT VALUE
CPSX_THRESHOLD var WORD 'VARIABLE FOR BUTTON THRESHOLD VALUE
CPSX_LAST var WORD 'VARIABLE FOR PREVIOUS BUTTON VALUE
Duty VAR WORD 'VARIABLE FOR DUTY CYCLE
stepp var byte 'VARIABLE FOR BRIGHTNESS LEVEL
incnt var byte 'BUTTON PUSH INCRIMENT
LOCLEV VAR BYTE 'LOCAL MODULE BRIGHTNESS LEVEL
REMLEV VAR BYTE 'REMOTE MODULE BRIGHTNESS LEVEL
IOTOG VAR BIT 'TOGGLE BIT FOR I/O BUTTON

' variables used by interrupt handler, comment out as per assembler
wsave VAR BYTE $20 SYSTEM ' location for W if in bank0
'wsave VAR BYTE $70 SYSTEM ' alternate save location for W
' if using $70, comment wsave1-3

' --- IF any of these three lines cause an error ?? ------------------------
' Comment them out to fix the problem ----
' -- Which variables are needed, depends on the Chip you are using --
wsave1 VAR BYTE $A0 SYSTEM ' location for W if in bank1
'wsave2 VAR BYTE $120 SYSTEM ' location for W if in bank2
'wsave3 VAR BYTE $1A0 SYSTEM ' location for W if in bank3





' SET DEVICE I/O PINS


LED1 VAR PORTA.1 ' SET LED LEVEL INDICATORS
LED2 VAR PORTA.2
LED3 VAR PORTA.3
LED4 VAR PORTA.4
LED5 VAR PORTA.5


' Software/Hardware initialization

PAUSE 50 ' OSC settle delay
Duty = 255 ' SET INITIAL BRIGHTNESS TO FULL ON
stepp = 5 ' SET INITIAL LOOKUP TABLE TO 5
incnt = 1 ' set input counter to input 1
iotog = 1 ' SET I/O BUTTON TOGGLE TO high
hpwm 1,DUTY,1000 ' INITIALIZE HARDWARE PWM TO SELECTED LEVELS
HIGH LED5 ' TURN ON OUTPUT FOR LED 5
pause 1000 ' LET EVERYTHING SETTLE

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
INT_Handler TMR0_INT, _Timer0_Int, pbp, yes
endm
INT_CREATE ; Creates the interrupt processor
ENDASM

TMR0 = 0 'clear TIMER0
@ INT_ENABLE TMR0_INT 'enable timer0 interrupts
PAUSE 100


'************************************************* **********************
'------------------------------< Main program >-------------------------

'SCAN INPUTS UNTIL FINGER DEPRESSION IS DETECTED
Main:

incnt = 2
cpscon1 = %00000001 ' 0001 = channel 1, (CPS1), DOWN BUTTON
ANSELB = %00000010 ' SETS INPUT B1 AS ANALOG
TRISB = %00000010 ' SETS INPUTS B1 AS INPUTS
PAUSE 100
INcnt = 3
cpscon1 = %00000010 ' 0010 = channel 2, (CPS2), UP BUTTON
ANSELB = %00000100 ' SETS INPUT B2 AS ANALOG
TRISB = %00000100 ' SETS INPUT B2 AS INPUT
PAuse 100
incnt = 1
cpscon1 = %00000000 ' 0000 = channel 0, (CPS0), 1/0 BUTTON
ANSELB = %00000001 ' SETS INPUT B0 AS ANALOG
TRISB = %00000001 ' SETS INPUT B0 AS INPUT
Pause 100 ' WAIT FOR INTERRUPT

Goto Main

'************************************************* ****************************
Timer0_Int:
@ INT_DISABLE TMR0_INT ; stop timer0 interrupts while we're in here
pause 100

' store away the present timer0 count for the next time we come into the interrupt routine
CPSX_PRESENT = TMR1 ' take a snapshot of Timer1's present count.
CPSX_THRESHOLD = CPSX_PRESENT - ((CPSX_LAST/10)*5) ' this sets the 'trigger' up for a 50% diversion (finger press)
CPSX_LAST = CPSX_PRESENT

'DETERMINES WHICH BUTTON HAS BEEN PRESSED
IF CPSX_PRESENT < CPSX_THRESHOLD THEN
if (incnt = 3) AND (STEPP > 1) then ' down button pressed so decriment stepp
stepp = stepp - 1
GOTO SKIP1
ENDIF
If (incnt = 2) AND (STEPP < 5) then ' up button pressed so incriment stepp
stepp = stepp + 1
GOTO SKIP1
endif
IF (INCNT = 1) AND (iotog = 0) THEN ' 1/0 button pressed for off
STEPP = 0
IOTOG = 1
GOTO SKIP1
ENDIF
IF (INCNT = 1) AND (iotog = 1) THEN ' 1/0 button pressed for on
STEPP = 5
IOTOG = 0
ENDIF


' lights appropriate leds according to the current lookup table value
SKIP1:
IF STEPP = 5 THEN
HIGH LED5
ENDIF
IF STEPP = 4 THEN
HIGH LED4
ENDIF
IF STEPP = 3 THEN
HIGH LED3
ENDIF
IF STEPP = 2 THEN
HIGH LED2
ENDIF
IF STEPP = 1 THEN
HIGH LED1
ENDIF
if stepp = 0 THEN
LOW LED1
endif



' SETS HARDWARE PWM OUTPUT 1 TO DESIRED LEVEL
lookup stepp, [0,16,32,64,128,255],duty ' choose level, 5 levels plus OFF
hpwm 1,duty,1000 ' set new level
' pause 100

ENDIF


pause 100
TMR0 = 0 ' clear TIMER0
TMR1 = 0 ' clear TIMER1
@ INT_ENABLE TMR0_INT ; re-enable timer0 interrupt
@ INT_RETURN

resume