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Hi Travis,
I'm assuming that you've just
connected pins 2 & 3 (and ground) from the PC to your circuit and not any of
the handshaking lines such as RTS, DTR and CTS. If this is true, in the
properties dialog for hyperterm where you configure the baudrate, there is a
field titled flowcontrol which normally defaults to "Hardware". Set it to none.
When set to hardware, Hyperterm will not transmit unless it sees the the CTS*
active.
Scott Kellish
----- Original Message -----
From: Travis L. F Bailey
To: p...@yahoogroups.com
Sent: Tuesday, January 27, 2004 11:45 PM
Subject: [piclist] Help with usart receive
Help,
I am missing some obvious
mistake. I just don't see it.
I am using a pic18f452 chip
and a max232 chip to communicate to my
laptop's serial
port. I can send data from the pic to the pc, but, I
can not
receive data from hyperterm to the pic chip. I am also connected
to a
ds1620 digital thermometer (That bit works fine).
I have attached the
MPLAB c18 c code that I am using. Let me know if
you see the error.
It is driving me crazy,
Thanks,
TravisCODE ******
#include <p18f452.h> /* for TRISB and PORTB declarations
*/
#include <delays.h>
#include <usart.h>
#include
<stdlib.h>
/* Port Defines */
#define RST PORTDbits.RD0
#define CLK PORTDbits.RD1
#define DQ PORTDbits.RD2
/*ds1620
Functions */
unsigned char write_config = 0x0c;
unsigned char
start_conv = 0xee;
unsigned char read_temp = 0xaa;
unsigned char DQin
= 4;
unsigned char DQout = 0;
void write_ds1620_bit (unsigned
char b)
/* This function sends a data bit to DS1620 */
{
DQ = b;
CLK = 0;
CLK = 1;
DQ = 1;
}
unsigned char read_ds1620_bit()
/*Reads a data bit */
{
unsigned char b;
TRISD = DQin;
CLK =
0;
b = DQ;
CLK = 1;
TRISD = DQout;
return (b);
}
void write_to_ds1620(unsigned char
ds1620_function, unsigned char
ds1620_data, unsigned char bit_count)
/* This function writes data/config to ds1620 */
{
unsigned
char i, this_bit;
RST = 1;
/* Send function */
for (i=0;i<8;i++)
{
this_bit =
ds1620_function >> i;
this_bit = this_bit &
0x01;
write_ds1620_bit(this_bit);
}
/* Send data */
for (i=0;i<bit_count;i++)
{
this_bit = ds1620_data >> i;
this_bit = this_bit & 0x01;
write_ds1620_bit(this_bit);
}
RST = 0;
}
unsigned int read_from_ds1620 (unsigned char ds1620_function, unsigned
char bit_count)
/*Reads data, conf from ds1620 */
{
unsigned char i, this_bit;
unsigned int ds1620_data;
ds1620_data = 0;
RST = 1;
/*send function
*/
for (i=0;i<8;i++)
{
this_bit = ds1620_function >> i;
this_bit =
this_bit & 0x01;
write_ds1620_bit(this_bit);
}
/*read data */
for
(i=0;i<bit_count;i++)
{
ds1620_data =
ds1620_data | read_ds1620_bit() << i;
}
RST =
0;
return (ds1620_data);
}
void main (void)
{
char temperature[4];
char triscout[4];
unsigned int temp;
unsigned long temp2;
int shorttime;
int longtime;
int
counter;
char data;
TRISB =
0; /*
configure PORTB for output, LED Bank */
LATB = 0;
shorttime = 5; /* Delay for loop */
longtime = 1000; /* Longer Delay for loop */
TRISD =
DQout; /* For ds1620 start */
LATC = 0;
TRISC = 0b10111111;
OpenUSART
(USART_TX_INT_OFF & USART_RX_INT_OFF &
USART_ASYNCH_MODE
& USART_EIGHT_BIT &
USART_CONT_RX
& USART_BRGH_LOW, 25);
/*config ds1620 for
continous operation */
write_to_ds1620(write_config,2,8);
Delay10KTCYx(longtime);
/* start conversion */
write_to_ds1620(start_conv,0,0);
Delay10KTCYx(longtime);
PORTB = 1;
data = 0;
while (1)
{
if
(DataRdyUSART())
{
/******************************
Problem is in here. I never get here,
never see input
*******************************/
data = ReadUSART();
putrsUSART ("Input: ");
WriteUSART ( data );
putrsUSART (" \r\n");
PORTB = 24;
Delay10KTCYx(longtime);
PORTB = 0;
Delay10KTCYx(longtime);
}
/* Start temp grab and convert */
temp = 0;
temp2 = 0;
temp =
read_from_ds1620(read_temp,9);
temp2 = temp / 2;
temp2 = temp2 * 1.8;
temp2 = temp2 + 32;
/* Output temp and other in put to screen */
ultoa(temp2,temperature);
putrsUSART ("
Temperature: " );
putsUSART ( &temperature );
putrsUSART (" F \r\n");
itoa(temp,temperature);
putrsUSART (" Temperature: " );
putsUSART ( &temperature );
putrsUSART (" C
\r\n");
itoa(TRISC,triscout);
putrsUSART (" TRISCOUT: ");
putsUSART ( &triscout );
putrsUSART (" \r\n");
putrsUSART ("
Data Input: ");
putsUSART ( &data );
putrsUSART (" \r\n");
putrsUSART ("
\r\n");
/* Show raw temp on LED bank */
PORTB = temp;
Delay10KTCYx(longtime);
Delay10KTCYx(longtime);
}
}
*****************************
Sample OutputTemperature: 73 F
Temperature: 47 C
TRISCOUT: 191
Data Input:
Temperature:
73 F
Temperature: 47 C
TRISCOUT: 191
Data Input:
Temperature: 73 F
Temperature: 47 C
TRISCOUT: 191
Data
Input:
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