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Guest
Guest
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| DMX problems receiving characters |
 Posted: Thu Oct 26, 2006 6:11 pm |
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I am using an 18F6520 at 16Mhz to receive DMX. I am using a hardware UART and an SN75176 level convertor. I am not getting valid level data. I am not attempting to detect the start of a DMX packet yet I am only resetting the port (cycling CREN) when I get an Overrun. I always get 0x82 as the level data no matter what level I send. The rcsta byte changes with different levels, ie. when sending 1>512@0 I get FERR (0xD4 for rcsta), when sending levels above zero I get 0xD1. Does anyone have any ideas what I am doing wrong or how to trouble shoot this further?
Below are relavent sections of code
| Code: |
#use rs232(baud=9600,parity=N,xmit=PIN_G1,rcv=PIN_G2,bits=8, ERRORS, STREAM=Serial)
#use rs232(baud=250000,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=9, STREAM=DMX)
#int_rda //DMX receive interupt service routine
void DMX_isr()
{
while (PIR1bits.RCIF)
{
fputc(DMX_rcsta, Serial);
fputc(data, Serial);
if (rcsta.OERR) //Overrun
{
rcsta.CREN = 0;
rcsta.CREN = 1;
}
}
return;
}
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Oct 26, 2006 9:06 pm |
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| You code never reads the data value from the uart. You also can't transmit those data byte inside the ISR. You will always get an overrun error. |
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Guest
Guest
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| reading data from uart |
| Posted: Fri Oct 27, 2006 8:41 am |
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| So do I need to use fgetc to read from the uart? Then put read data into a buffer and send from the buffer between interrupts? Thank you for the help. |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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Guest
Guest
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| Thanks |
| Posted: Fri Oct 27, 2006 6:37 pm |
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| Thanks Mark! Its funny how it works when you actually read the value from the uart! Better a stupid mistake than a hardware problem. Thank you again for your help. |
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spradecom.rnd
Joined: 27 Apr 2010
Posts: 16
Location: Mumbai
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| DMX receiving problem |
| Posted: Wed Aug 11, 2010 12:13 am |
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I wrote a code like the others based on Mark's code found in this forum, following the same ideas, but it doesn't work. The first problem is that the usart never generates a FERR error to detect the break. Second problem is about baud rate. Is this | Code: | | #USE RS232(baud=250000,rcv=PIN_C7,xmit=PIN_C6) |
enough for setting baud rate or do we have to separately initialize using SPBRg reg ?
Here is my code
| Code: |
#include <16F1938.h>
#device adc=8
#FUSES NOWDT //No Watch Dog Timer
//#FUSES INTRC_IO //Internal RC Osc, no CLKOUT
#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES MCLR //Master Clear pin enabled
#FUSES NOCPD //No EE protection
#FUSES NOBROWNOUT //No brownout reset
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES FCMEN //Fail-safe clock monitor enabled
#FUSES WDT_SW
#FUSES NOCLKOUT
#FUSES NOWRT //Program memory not write protected
#FUSES NOVCAP
#FUSES PLL
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES BORV19
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NODEBUG //No Debug mode for ICD
#use delay(clock =16000000)
#USE RS232(baud=250000,rcv=PIN_C7,xmit=PIN_C6)
//-----------Register Definition---------------------
//----------------------------------------------------
/************************************************************************
* Registrers USART *
************************************************************************/
#word SPBRG = 0x19B
//#word MCU_SPBRG = 0x19B
#byte RCSTA = 0x19D
//#byte MCU_RCSTA = 0x19D
#byte TXSTA = 0x19E
//#byte MCU_TXSTA = 0x19E
#byte RCREG = 0x199
//#byte MCU_RCREG = 0x199
#byte PIR1 = 0x011
//#byte MCU_PIR1 = 0x011
#byte PIE1 = 0x091
//#byte MCU_PIE1 = 0x091
#byte INTCON = 0x00B
//#byte MCU_INTCON = 0x00B
#bit SPEN = RCSTA.7 //Serial port enable bit
#bit RX9 = RCSTA.6 // 9-bit receive enable
#bit SREN = RCSTA.5
#bit CREN = RCSTA.4 // Continuos receive enable bit
#bit ADDEN = RCSTA.3
#bit FERR = RCSTA.2 //Frame error bit
#bit OERR = RCSTA.1 //Overrun error bit
#bit RX9D = RCSTA.0
#bit BRGH = TXSTA.2
#bit SYNC = TXSTA.4
#bit RCIF = PIR1.5
#bit RCIE = PIE1.5
#bit GIE = INTCON.7
#bit PEIE = INTCON.6
//----------------------------------------------------
#byte BAUDCON = 0x19F
#bit ABDEN = BAUDCON.0
#bit WUE = BAUDCON.1
#bit BRG16 = BAUDCON.3
#bit SCKP = BAUDCON.4
#bit RCIDL = BAUDCON.6
#bit ABDOVF = BAUDCON.7
/************************************************************************
* Function Decleration *
************************************************************************/
void Interrupt_USART_Rx(void);
void togglea1(void);
void togglea0(void);
//---------------------------------------------------------------------
/************************************************************************
* Global Variables *
************************************************************************/
#define MAX_PWMS 3
/*Rx Buffer for dmx stream */
//int8 Rx_Buffer[512];
int8 Rx_Buffer[MAX_PWMS];
/*Current levels -0 to 255 */
int8 DMX_Levels[MAX_PWMS];
int1 Check_levels=0;
#include <main.h>
#int_RDA
void RDA_isr(void)
{
//void Interrupt_USART_Rx(void)
//{
#define WAIT_FOR_NEXT_BYTE 0
#define WAIT_FOR_BREAK 1
#define WAIT_FOR_START 2
#define RECEIVE_DATA 3
static int8 Rx_State = WAIT_FOR_BREAK;
int8 data;
union
{
unsigned char fullbyte;
struct {
unsigned char RX9D:1; //bit0
unsigned char OERR:1;
unsigned char FERR:1;
unsigned char ADDEN:1;
unsigned char CREN:1;
unsigned char SREN:1;
unsigned char RX9:1;
unsigned char SPEN:1; //bit7
} bits ;
}rcsta;
static int8 *ptr_Rx;
static unsigned int DMX_512_Count = 0;
while(RCIF)
{
//togglea1();
rcsta.fullbyte = RCSTA;
// read data - reading data also clears 'rcif' flag
// and reading 'rcreg' will cause the second 'rcsta' to be loaded if there is one
data = RCREG;
if (rcsta.bits.OERR) //check for overrun
{
//If there Overrun then reset the reception
CREN = 0;
CREN = 1;
// received a buffer overun so, wait for a good data byte before looking for
// a break signal
// togglea1();
Rx_State = WAIT_FOR_NEXT_BYTE;
return;
}
switch (Rx_State)
{
case WAIT_FOR_NEXT_BYTE:
if (!rcsta.bits.FERR)
//togglea1();
Rx_State = WAIT_FOR_BREAK;
break;
case WAIT_FOR_BREAK:
/* If we did receive a framing error, make sure that the data is 0.
This means that we did Receive the break signal for at least 44us. */
if (rcsta.bits.FERR) // frame eror bit
{
togglea1();
if (!data)
//togglea1();
Rx_State = WAIT_FOR_START;
}
break;
case WAIT_FOR_START:
// check for a framing error. if we receive one we will have to wait
// until we receive a good data byte before we begin looking for our break signal
if (rcsta.bits.FERR)
// togglea1();
Rx_State = WAIT_FOR_NEXT_BYTE;
/* The start code for our data packet should always start with 0. */
else
{
if (!data)
{
/* Initialize our index to our reception buffer */
ptr_Rx = Rx_Buffer;
Rx_State = RECEIVE_DATA;
}
}
break;
case RECEIVE_DATA:
if (rcsta.bits.FERR)
{
if (!data)
Rx_State = WAIT_FOR_START;
else
Rx_State = WAIT_FOR_NEXT_BYTE;
}
else
{
/* Store the data received in the reception buffer */
*ptr_Rx=data;
ptr_Rx++;
if(ptr_Rx > &Rx_Buffer[MAX_PWMS-1] )
{
Check_levels=1;
Rx_State= WAIT_FOR_BREAK;
}
}
break;
}
}
return;
//}
}
void main()
{
int8 i;
SPBRG=0x03;
BRG16 = 0 ;
BRGH=1;
SYNC=0;
SPEN=1;
RX9=1; // 9 bit reception
//RX9D=1;
CREN=1; // enable reception
ADDEN=0;
FERR=1;
OERR=1;
delay_ms(3000);
setup_adc_ports(NO_ANALOGS| VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2);
setup_spi(SPI_SS_DISABLED);
setup_lcd(LCD_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DIV_BY_16,255,1);
setup_ccp1(CCP_PWM);
setup_ccp2(CCP_PWM);
setup_ccp4(CCP_PWM);
set_pwm1_duty(0);
set_pwm2_duty(0);
set_pwm4_duty(0);
setup_comparator(NC_NC_NC_NC);// This device COMP currently not supported by the PICWizard
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
//TODO: User Code
//set_pwm1_duty(127);
//set_pwm2_duty(127);
//set_pwm4_duty(127);
delay_ms(1000);
GIE=1; // enable all interrupts
PEIE=1; // enable peripheral interrupts
RCIE=1; // enable receive interrupt
while (TRUE)
{
// set_pwm1_duty(700);
//set_pwm2_duty(700);
//set_pwm4_duty(700);
//--------------------------------------
if (Check_levels)
{
Check_levels=0;
DMX_Levels[0]=Rx_Buffer[0];
DMX_Levels[1]=Rx_Buffer[1];
DMX_Levels[2]=Rx_Buffer[2];
set_pwm1_duty(DMX_Levels[0]);
set_pwm2_duty(DMX_Levels[1]);
set_pwm4_duty(DMX_Levels[2]);
}
//----------------------------------------
}
}
//----------------------------
void togglea1(void)
{
output_high(PIN_A1);
delay_ms(200);
output_low(PIN_A1);
delay_ms(200);
}
void togglea0(void)
{
output_high(PIN_A0);
delay_ms(100);
output_low(PIN_A0);
delay_ms(100);
} |
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