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Bill_Smith
Joined: 06 Feb 2004
Posts: 26
Location: Curitiba, Brazil
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| #Use I2C() and SSP interrupts not working on PIC16F883 |
 Posted: Sun Aug 17, 2008 11:33 pm |
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I have a really strange I2C problem that I want to share with you all in hopes that someone can shed some light on a solution.
Hardware:
PIC16F883 (On the MCP1631 Multi-Chemistry Battery Charger Reference Design Demo Board)
Compiler:
CCS PCWHD version 4.077
ICD Environment:
MPLAB 8.14 with RealICE debugger
Problem #1:
The #use i2c(SLAVE, SDA=PIN_C3, SCL=PIN_C4, ADDRESS=0x22) compiler directive does not setup the PIC16F883 MSSP module. The following code was compiled and run on the target board.
| Code: |
#include <16F883.h>
#device ADC=10
#fuses INTRC,NOWDT,MCLR,DEBUG,NOPROTECT,NOLVP,NOBROWNOUT,NOPUT,NOCPD
#use delay(clock=8000000) // 8MHz Clock
#use i2c(SLAVE, SDA=PIN_C3, SCL=PIN_C4, ADDRESS=0x22)
#byte SSPSTAT = 0x094
#byte SSPCON2 = 0x091
#byte SSPADD = 0x093
#byte SSPCON = 0x014
#byte PIR1 = 0x00C
#bit GCEN = SSPCON2.7
#bit SSPIF = PIR1.3
#INT_SSP
void ssp_interupt(void)
{
if(SSPIF)
SSPIF = 0;
delay_us(1);
delay_us(1);
delay_us(1);
}// End ISR SSP
void main(void)
{
setup_oscillator(OSC_8MHZ,0); //set oscillator to 8Mhz
set_tris_c (0b00011000); // C3 and C4 are INPUTS
//SSPCON = 0b00110110;
GCEN = 1; // Allow General Calls
//SSPADD = 0x22; // Slave Device Address
enable_interrupts(INT_SSP); // Enable I2C Interrupts
enable_interrupts(GLOBAL); // Enable Global Interrupts
while(TRUE)
{
}
}
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Debugger Watch Window shows:
Address Symbol Name Value
014 SSPCON 00000000
091 SSPCON2 10000000
094 SSPSTAT 00000000
093 SSPADD 0x00
00C PIR1 00000000
013 SSPBUF 0x44
Then I checked to see if I could directly set the register values.
| Code: |
#include <16F883.h>
#device ADC=10
#fuses INTRC,NOWDT,MCLR,DEBUG,NOPROTECT,NOLVP,NOBROWNOUT,NOPUT,NOCPD
#use delay(clock=8000000) // 8MHz Clock
//#use i2c(SLAVE, SDA=PIN_C3, SCL=PIN_C4, ADDRESS=0x22)
#byte SSPSTAT = 0x094
#byte SSPCON2 = 0x091
#byte SSPADD = 0x093
#byte SSPCON = 0x014
#byte PIR1 = 0x00C
#bit GCEN = SSPCON2.7
#bit SSPIF = PIR1.3
#INT_SSP
void ssp_interupt(void)
{
if(SSPIF)
SSPIF = 0;
delay_us(1);
delay_us(1);
delay_us(1);
}// End ISR SSP
void main(void)
{
setup_oscillator(OSC_8MHZ,0); //set oscillator to 8Mhz
set_tris_c (0b00011000); // C3 and C4 are INPUTS
SSPCON = 0b00110110;
GCEN = 1; // Allow General Calls
SSPADD = 0x22; // Slave Device Address
enable_interrupts(INT_SSP); // Enable I2C Interrupts
enable_interrupts(GLOBAL); // Enable Global Interrupts
while(TRUE)
{
}
}
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This time when running the compiled program, I get the expected results.
Debugger Watch Window shows:
Address Symbol Name Value
014 SSPCON 00110110
091 SSPCON2 10000000
094 SSPSTAT 00000000
093 SSPADD 0x22
00C PIR1 00000000
013 SSPBUF 0x44
Problem #2:
INT_SSP never occurs.
With a known GOOD I2C Master, I generated a simple QuickWrite transaction, which essentially sends the following:
i2c_start(); // [START]
ack = i2c_write((address<<1)|0x00); // [ADDRESS + W]
i2c_stop(); // [STOP]
I set a breakpoint on the first delay_us(1); statement in the SSP_ISR and ran the program.
Without any code in the SSP isr I am not expecting it to respond, but i did expect the SSP interrupt to occur and stop at the breakpoint. This did not happen.
I ran this same code on a PIC16F88 target board and everything works as expected.
Does anyone have any suggestions? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Aug 18, 2008 12:32 am |
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| Quote: | | #use i2c(SLAVE, SDA=PIN_C3, SCL=PIN_C4, ADDRESS=0x22) |
You have the SDA and SCL pins reversed. That's why the code
generation is not correct.
| Quote: | i2c_start(); // [START]
ack = i2c_write((address<<1)|0x00); // [ADDRESS + W]
i2c_stop(); // [STOP] |
What is contents of the 'address' variable before it is shifted left ?
I want to check if you are confusing the 8-bit slave address format
used by CCS and Microchip, and the 7-bit format used by Philips. |
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Bill_Smith
Joined: 06 Feb 2004
Posts: 26
Location: Curitiba, Brazil
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| Posted: Mon Aug 18, 2008 11:39 am |
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Wow PCM, sorry about this. I guess I need some sleep. You were spot on with the pins being reversed and the device address. Changing the #use i2c statement to the following loaded all the MSSP registers correctly.
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, ADDRESS=0x44)
Rolling the device address bits 1 position to the left so that I am loading the SPPADD register with [0x44], instead of [0x22], solved the No SSP_INT problem as well. I guess CCS must have recently changed how the compiler interprets the I2C Slave address. I could have sworn it used to be as I first had it.
Anyway everything is working now. Thank you for your help.
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danishamjad
Joined: 28 Apr 2015
Posts: 1
Location: Pakistan
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| Same Issue-- Interrupt is not firing |
| Posted: Tue Apr 28, 2015 9:56 am |
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I am trying simple project to study i2c. I am using PIC18F4550 and CCS PIC C compiler.
Here is a scenario.
Master:
1. Button is connected to PIN_E1.
2. When Button is pressed, it sends code 0x01 to slave.
3. When Button is pressed again, it sends code 0x02 to slave.
Slave:
1. Only one slave is connected. It's address is 0x0a.
2. When it receives 0x01, it should turn LED on connected at PIN_E0.
3. When it receives 0x02, it should turn LED off.
I was observing SCL and SDA on oscilloscope and found correct pattern always, when the button is pressed.
But interrupt in slave is not working at all. I just changed slave scenario:
1. LED is turned off at first.
2. Whenever interrupt is fired it should remain turn on.
Here is my slave code:
| Code: |
#include <18F4550.h>
#device adc=16
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES CPUDIV4 //System Clock by 4
#FUSES XT //Crystal osc <= 4mhz for PCM/PCH , 3mhz to 10 mhz for PCD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#use delay(crystal=20000000, clock=5000000)
#use i2c(SLAVE, sda=PIN_B0, scl=PIN_B1, address=0x0a, force_hw)
BYTE address, buffer[0x10];
#INT_SSP
void ssp_interupt (){
BYTE incoming, state;
state = i2c_isr_state();
if(state < 0x80) //Master is sending data
{
incoming = i2c_read();
if(state == 1) //First received byte is address
address = incoming;
if(state == 2) //Second received byte is data
buffer[address] = incoming;
}
if(state == 0x80) //Master is requesting data
{
i2c_write(buffer[address]);
}
output_high(PIN_E0);
}
void main()
{
setup_timer_3(T3_DISABLED | T3_DIV_BY_1);
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
set_tris_B ( 0b01111111 );
set_tris_e(0x06);
output_low(PIN_E0);
while(1){}
}
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Kindly, tell me if I'm doing something wrong. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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