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asiklariskostas
Joined: 07 Jul 2013
Posts: 16
Location: Greece
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| PIC18F4550 & HTF3223 |
 Posted: Sun Jul 07, 2013 6:42 am |
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Hello everyone,
It's my first topic in the forum. I have a problem with communication between my PIC18f4550 and the sensor HTF3223. I use the example program by PICC after I made some changes, but my microcontroller doesn't read the frequency from the sensor.
The sensor is ok. I measured the frequency and the measurements were normal. Can anyone help me??? Below i have the program that i have created.
EX_HUMDITY.C:
| Code: |
/////////////////////////////////////////////////////////////////////////
//// EX_HUMIDITY.C ////
//// ////
//// This program displays the relative humity, in percent (RH%), ////
//// read by a Humirel HT3223/HTF3223 Humidity Module. ////
//// ////
//// Configure the CCS prototype card as follows: ////
//// Insert jumpers from output of POT to pin A0 ////
//// ////
//// This example will work with the PCM and PCH compilers. The ////
//// following conditional compilation lines are used to include a ////
//// valid device for each compiler. Change the device, clock and ////
//// RS232 pins for your hardware if needed. ////
/////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,2005 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS ////
//// C compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, ////
//// reproduction or distribution is permitted without written ////
//// permission. Derivative programs created using this software ////
//// in object code form are not restricted in any way. ////
/////////////////////////////////////////////////////////////////////////
#if defined(__PCM__)
#include <16F877A.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#elif defined(__PCH__)
#include <main.h>
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#endif
#include <ht3223.c>
void main(void) {
int8 rh;
printf("\r\n\nRelative Humidity:\r\n");
humidity_init();
enable_interrupts(TRUE);
while (!humidity_ready()) {}
while(TRUE) {
humidity_read();
printf("\r\n%U%%",rh);
delay_ms(1000);
}
}
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main.h:
| Code: |
#include <18F4550.h>
#device adc=10
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT32768 //Watch Dog Timer uses 1:128 Postscale
#FUSES HSPLL //High Speed Crystal/Resonator with PLL enabled
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOBROWNOUT //No brownout reset
#FUSES BORV20 //Brownout reset at 2.0V
#FUSES PUT //No Power Up Timer
#FUSES NOCPD //No EE protection
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOWRT //Program memory not write protected
#FUSES NOWRTD //Data EEPROM not write protected
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES FCMEN //Fail-safe clock monitor enabled
#FUSES NOPBADEN ///PORTB pins are configured as analog input channels on RESET
#FUSES NOWRTC //configuration not registers write protected
#FUSES NOWRTB //Boot block not write protected
#FUSES NOEBTR //Memory not protected from table reads
#FUSES NOEBTRB //Boot block not protected from table reads
#FUSES NOCPB //No Boot Block code protection
#FUSES MCLR //Master Clear pin enabled
#FUSES LPT1OSC //Timer1 configured for low-power operation
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#FUSES PLL5 //Divide By 12(48MHz oscillator input)
#FUSES CPUDIV1 //System Clock by 2
#FUSES USBDIV //USB clock source comes from PLL divide by 2
#FUSES VREGEN //USB voltage regulator enabled
#FUSES ICPRT //ICPRT enabled
#FUSES WRTB
#FUSES NOICPRT
#FUSES LPT1OSC //NO
#FUSES CCP2B3
#FUSES NOCPB
#FUSES NOCPD
#FUSES NOWRTC
#FUSES NOWRTD
#FUSES NOEBTR
#FUSES NOEBTRB
/* systm clock is 48 MHz */
#use delay(clock=48000000,RESTART_WDT)
/* --- BEGIN: changes required for bootloader ------------------------------ */
/* ------------------------------------------------------------------------- */
/* map reset vector and interrupt vector */
/* 0x000-0x7FF is used by the bootloader. The bootloader maps the original */
/* reset vecotr (0x000) to 0x800 and the reset vector (0x008) to 0x800. */
/* ------------------------------------------------------------------------- */
#build (reset=0x800, interrupt=0x808)
/* ------------------------------------------------------------------------- */
/* reserve boot block area */
/* This memory range is used by the bootloader, so the application must not */
/* use this area. */
/* ------------------------------------------------------------------------- */
#org 0, 0x7FF {}
/* --- END: changes required for bootloader -------------------------------- */
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HF3223.h:
| Code: |
//////////////////////////////////////////////////////////////////////////////
//// ////
//// HT3223.C - Driver for Humirel HT3223/HTF3223 Humidity Module ////
//// ////
//// HT3223 has 3 pins: Power, Ground and Output. The Output pin is ////
//// a square wave with the frequency denoting the RH% (relative ////
//// humidty, in percent). ////
//// ////
//// The math equation is: Fout = 9740 - 18*RH ////
//// or: RH = (9740 - Fout)/18 ////
//// ////
//// Connect the HT3223 output pin to the CCP1 pin of the PIC. This ////
//// library will configure the CCP1 to act as a capture, and calculate ////
//// the frequency of Fout based upon the last two captures. ////
//// NOTE: Some PICs let you change the CCP1 timer to TIMER3. Do not ////
//// change this setting, leave the CCP1 timer to TIMER1. ////
//// ////
//////////////////////////////////////////////////////////////////////////////
//// ////
//// HT3223.C Functions: ////
//// ////
//// humidity_init() - Must be called before other humidity functions ////
//// are called. Configures the CCP1 and TIMER1, and ////
//// enables the CCP1 interrupt. ////
//// NOTE: You must enable global_interrupts() in your ////
//// application. ////
//// ////
//// humidity_read() - Returns the RH%, an int8 ranging from 0 to 100. ////
//// ////
//// humidity_ready() - The driver keeps the last 15 frequency counts in ////
//// memory. This function returns TRUE if we have read 15 ////
//// counts. If it returns FALSE wait a little bit longer. ////
//// ////
//////////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,2005 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS C ////
//// compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, reproduction ////
//// or distribution is permitted without written permission. ////
//// Derivative programs created using this software in object code ////
//// form are not restricted in any way. ////
//////////////////////////////////////////////////////////////////////////////
#define HUMIDITY_NUM_SAMPLES 15
int16 humidity_samples[HUMIDITY_NUM_SAMPLES];
int8 humidity_sample_index=0;
int1 __humidity_ready=FALSE;
#define humidity_ready() __humidity_ready
void humidity_init(void) {
setup_ccp1(CCP_CAPTURE_FE); // Configure CCP2 to capture fall
setup_timer_1(T1_INTERNAL);
clear_interrupt(INT_CCP1);
enable_interrupts(INT_CCP1);
}
int8 humidity_read(void) {
int8 i;
int8 num=0;
int32 freq;
int32 freq_sum=0;
int16 ticks;
for (i=0;i<HUMIDITY_NUM_SAMPLES;i++) {
freq=getenv("CLOCK")/4;
freq/=humidity_samples[i];
if ((freq < 9741) && (freq > 7800)) {
num++;
freq_sum+=freq;
}
}
if (num)
freq=freq_sum / num;
else
freq=9740;
i = ((9740 - freq) / 18);
return(i);
}
#define TickGetDiff(a, b) ((int16)(a < b) ? (((int16)0xffff - b) + a + 1) : (a - b))
#int_ccp1
void humidity_isr(void) {
static int8 first=1;
static int16 last;
if (!first) {
humidity_samples[humidity_sample_index++]=TickGetDiff(CCP_1,last);
if (humidity_sample_index >= HUMIDITY_NUM_SAMPLES) {
humidity_sample_index=0;
__humidity_ready=TRUE;
}
}
else
first=0;
last=CCP_1;
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jul 07, 2013 10:34 am |
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| Quote: | void main(void) {
int8 rh;
printf("\r\n\nRelative Humidity:\r\n");
humidity_init();
enable_interrupts(TRUE);
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'TRUE' is not a valid parameter for that function. Look at any CCS
example program that uses interrupts. Besides enabling the specific
interrupt, what parameter is used to globally enable interrupts ?
You can look at this one:
| Quote: | | c:\program files\picc\examples\ex_ccpmp.c |
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asiklariskostas
Joined: 07 Jul 2013
Posts: 16
Location: Greece
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| Posted: Sun Jul 07, 2013 11:13 am |
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| So, first i have to enable GLOBAL interrupts and then interrupts in CCP1, right??? But it didn't work again. My sensor has only one pin for the frequency. So, i connect only this pin to CCP1. Have i to connect the CCP2 to ground??? I 'm sorry that I can't understand the Interrupts. I am beginner with this function... |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jul 07, 2013 12:32 pm |
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I just realized that this code, is actually CCS code. For a while I thought
that you just copied the CCS copyright stuff into your own code. That's
because you said "the program that i have created".
But it's CCS code. This line is CCS's bug in ex_humidty.c:
| Code: | | enable_interrupts(TRUE); |
To me, that puts their whole driver into question.
I'll look at it some more, later this afternoon. I have to go out now. |
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asiklariskostas
Joined: 07 Jul 2013
Posts: 16
Location: Greece
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| Posted: Sun Jul 07, 2013 2:00 pm |
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 I 've changed the default example from CCS, so i can use my microcontroller. It is strange, but i don't know either many things about interrupts and that makes it more difficult to me. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jul 07, 2013 7:30 pm |
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Try this program, which displays the frequency of the HTF3223 signal
that is connected to the CCP1 input (pin 17) of the 18F4550.
I don't have an HTF3223, so I used the CCP2 module in PWM mode to
generate a test signal of 9375 Hz. For testing I connected the CCP2
pin to the CCP1 pin with a jumper wire. I got this output on the
TeraTerm window from the program below.
| Code: |
Start
9375 Hz
9375 Hz
9375 Hz
9375 Hz
9375 Hz
9375 Hz
9375 Hz
9375 Hz
9375 Hz
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The program is correctly measuring the input frequency. I used 9375 Hz
as the test signal, because it corresponds to 20% humidity for the HTF3223.
It's a reasonable test value to use.
Run this program on your board, and see if you get a frequency in the
correct range for the humidity in your room:
| Code: |
#include <18F4550.h>
#fuses HSPLL,NOWDT,BROWNOUT,PUT,PLL5,CPUDIV1
#use delay(clock=48M)
#use rs232(baud=9600, UART1, ERRORS)
// This global variable holds the time interval
// between two consecutive rising edges of the
// input signal.
int16 isr_ccp_delta;
#int_ccp1
void ccp1_isr(void)
{
int16 current_ccp;
static int16 old_ccp = 0;
// Read the 16-bit hardware CCP1 register
current_ccp = CCP_1; // From the PIC's .h file
// Calculate the time interval between the
// previous rising edge of the input waveform
// and the current rising edge. Put the result
// in a global variable, which can be read by
// code in main().
isr_ccp_delta = current_ccp - old_ccp;
// Save the current ccp value for the next pass.
old_ccp = current_ccp;
}
//=======================
void main()
{
int16 current_ccp_delta;
int16 frequency;
printf("Start \n\r");
/*
// This section of code below (3 lines) is for testing only.
// Do not use it with a real HT3223 chip.
// The CCP2 will be used in PWM mode to output a test
// signal that can be connected to the CCP1 pin.
setup_ccp2(CCP_PWM);
setup_timer_2(T2_DIV_BY_16, 79, 1); // 9.375 KHz PWM freq @ 48MHz osc
set_pwm2_duty(40); // 50% duty cycle on pin C1 (CCP2)
*/
// Setup Timer1 and CCP1 for Capture mode so that
// we can measure the input signal's frequency.
// The input signal comes from the CCP2 pin, which
// is connected to the CCP1 pin with a wire.
set_timer1(0);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_1);
setup_ccp1(CCP_CAPTURE_RE);
// Clear the CCP1 interrupt flag before we enable
// CCP1 interrupts, so that we don't get an unwanted
// immediate interrupt (which might happen).
clear_interrupt(INT_CCP1);
enable_interrupts(INT_CCP1);
enable_interrupts(GLOBAL);
while(1)
{
// Get a local copy of the latest ccp delta from the isr.
// We have to disable interrupts when we read a global
// isr variable that is larger than a single byte.
disable_interrupts(GLOBAL);
current_ccp_delta = isr_ccp_delta;
enable_interrupts(GLOBAL);
frequency = (int16)((12000000L + (current_ccp_delta >> 1)) / current_ccp_delta);
// Display the calculated frequency.
printf("%lu Hz\n\r", frequency);
delay_ms(500);
}
} |
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asiklariskostas
Joined: 07 Jul 2013
Posts: 16
Location: Greece
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| Posted: Mon Jul 08, 2013 2:59 pm |
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Thanks a lot...
The program worked. I tried in the kitchen and the frequency is 8843Hz, so it has about 50% humidity according to the htf 3223 datasheet. The outside humidity according to the weather report, Koeln has 42% of humidity, so i believe that measure is correct. It may have a deflection from -5 to +5% but it is ok. I will study carefully the code and then, If i have any questions, I won't hesitate to make them. |
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