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Jim
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| Problem when modify the rs485 driver rs485.c |
 Posted: Sat May 27, 2006 11:19 pm |
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hi,
I am modifying the CCS driver rs485.c so that instead of having the Format: source | destination | data-length | data | checksum, it will have the following modified format:
Start-of-TX-char| source | destination | data-length | data | checksum
I defined the Start-of-TX-char as '^'.
The problem that I don't see the Start-of-TX-char as the first received character for a giving TXed, but I see the "source". Do you guys have any pointer? Here is the modified code from rs485.c. I am using PCH 3.228 and PIC16F876 and PIC16F628A ( the CCS RFID development kit)
| Code: |
#ifndef RS485_DRIVER
#define RS485_DRIVER
#ifndef RS485_ID
#define RS485_ID 0x10 // The device's RS485 address or ID
#endif
#ifndef RS485_USE_EXT_INT
#define RS485_USE_EXT_INT FALSE // Select between external interrupt
#endif // or asynchronous serial interrupt
#if(RS485_USE_EXT_INT == FALSE)
#ifndef RS485_RX_PIN
#define RS485_RX_PIN PIN_C7 // Data receive pin
#endif
#ifndef RS485_TX_PIN
#define RS485_TX_PIN PIN_C6 // Data transmit pin
#endif
#ifndef RS485_ENABLE_PIN
#define RS485_ENABLE_PIN PIN_B4 // Controls DE pin. RX low, TX high.
#endif
#ifndef RS485_RX_ENABLE
#define RS485_RX_ENABLE PIN_B5 // Controls RE pin. Should keep low.
#endif
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, errors, stream=RS485)
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, force_sw, multi_master, errors, stream=RS485_CD)
#if getenv("AUART")
#define RCV_OFF() {setup_uart(FALSE);}
#else
#define RCV_OFF() {setup_uart(FALSE);}
#endif
#else
#ifndef RS485_RX_PIN
#define RS485_RX_PIN PIN_B0 // Data receive pin
#endif
#ifndef RS485_TX_PIN
#define RS485_TX_PIN PIN_B3 // Data transmit pin
#endif
#ifndef RS485_ENABLE_PIN
#define RS485_ENABLE_PIN PIN_B4 // Controls DE pin. RX low, TX high.
#endif
#ifndef RS485_RX_ENABLE
#define RS485_RX_ENABLE PIN_B5 // Controls RE pin. Should keep low.
#endif
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, errors, stream=RS485)
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, multi_master, errors, stream=RS485_CD)
#define RCV_OFF() {disable_interrupts(INT_EXT);}
#endif
#define RS485_wait_time 20 // Wait time in milliseconds
#bit rs485_collision = rs232_errors.6
#ifndef RS485_RX_BUFFER_SIZE
#define RS485_RX_BUFFER_SIZE 40
#endif
int rs485_state, rs485_ni, rs485_no;
int rs485_buffer[RS485_RX_BUFFER_SIZE];
[b]static int8 msg_hearder = '^'; /* start of the message char */[/b]
// Purpose: Enable data reception
// Inputs: None
// Outputs: None
void RCV_ON(void) {
#if (RS485_USE_EXT_INT==FALSE)
while(kbhit(RS485)) {getc();} // Clear RX buffer. Clear RDA interrupt flag. Clear overrun error flag.
#if getenv("AUART")
setup_uart(UART_ADDRESS);
setup_uart(TRUE);
#else
setup_uart(TRUE);
#endif
#else
clear_interrupt(INT_EXT);
enable_interrupts(INT_EXT);
#endif
}
// Purpose: Initialize RS485 communication. Call this before
// using any other RS485 functions.
// Inputs: None
// Outputs: None
void rs485_init() {
RCV_ON();
rs485_state=0;
rs485_ni=0;
rs485_no=0;
#if RS485_USE_EXT_INT==FALSE
enable_interrupts(INT_RDA);
#else
ext_int_edge(H_TO_L);
enable_interrupts(INT_EXT);
#endif
enable_interrupts(GLOBAL);
output_low(RS485_RX_ENABLE);
}
// The index for the temporary receive buffer
int8 temp_ni;
// Purpose: Add a byte of data to the temporary receive buffer
// Inputs: The byte of data
// Outputs: None
void rs485_add_to_temp(int8 b) {
// Store the byte
rs485_buffer[temp_ni] = b;
// Make the index cyclic
if(++temp_ni >= RS485_RX_BUFFER_SIZE)
{
temp_ni = 0;
}
}
// Purpose: Interrupt service routine for handling incoming RS485 data
#if (RS485_USE_EXT_INT==FALSE)
#int_rda
#else
#int_ext
#endif
void incomming_rs485() {
int16 b;
static int8 cs,state=0,len;
static int16 to,source;
[b]static int1 header_find = FALSE;[/b]
b=fgetc(RS485);
[b] if (!header_find)
{
if (msg_hearder == b)
{
header_find = TRUE;
}
return;
}[/b]
cs^=(int8)b;
switch(state) {
case 0: // Get from address
temp_ni=rs485_ni;
source=b;
cs=b;
rs485_add_to_temp(source);
break;
case 1: // Get to address
to=b;
#if (getenv("AUART")&&(RS485_USE_EXT_INT==FALSE))
setup_uart(UART_DATA);
#endif
break;
case 2: // Get len
len=b;
rs485_add_to_temp(len);
break;
case 255: // Get checksum
if ((!cs)&&(bit_test(to,8))&&(bit_test(source,8))&&((int8)to==RS485_ID))
{ // If cs==0, then checksum is good
rs485_ni=temp_ni;
}
#if (getenv("AUART")&&(RS485_USE_EXT_INT==FALSE))
setup_uart(UART_ADDRESS);
#endif
header_find = FALSE;
state=0;
return;
default: // Get data
rs485_add_to_temp(b);
--len;
break;
}
if ((state>=3) && (!len)) {
state=255;
}
else {
++state;
}
}
// Purpose: Send a message over the RS485 bus
// Inputs: 1) The destination address
// 2) The number of bytes of data to send
// 3) A pointer to the data to send
// Outputs: TRUE if successful
// FALSE if failed
// Note: Format: source | destination | data-length | data | checksum
int1 rs485_send_message(int8 to, int8 len, int8* data) {
int8 try, i, cs;
int1 ret = FALSE;
RCV_OFF();
#if RS485_USE_EXT_INT
disable_interrupts(GLOBAL);
#endif
for(try=0; try<5; ++try)
{
rs485_collision = 0;
[b] fputc(msg_hearder, RS485_CD);[/b]
fputc((int16)0x100|rs485_id, RS485_CD);
fputc((int16)0x100|to, RS485_CD);
fputc(len, RS485_CD);
for(i=0, cs=rs485_id^to^len; i<len; ++i) {
cs ^= *data;
fputc(*data, RS485_CD);
++data;
}
fputc(cs, RS485_CD);
if(!rs485_collision) {
ret = TRUE;
break;
}
delay_ms(RS485_ID);
}
RCV_ON();
#if RS485_USE_EXT_INT
enable_interrupts(GLOBAL);
#endif
return(ret);
}
// Purpose: Wait for wait time for the RS485 bus to become idle
// Inputs: TRUE - restart the watch dog timer to prevent reset
// FALSE - watch dog timer not restarted
// Outputs: None
void rs485_wait_for_bus(int1 clrwdt)
{
int16 i;
RCV_OFF();
for(i=0; i <= (rs485_wait_time*20); ++i)
{
if(!input(RS485_RX_PIN))
i = 0;
else
delay_us(50);
if(clrwdt)
restart_wdt();
}
}
// Purpose: Get a message from the RS485 bus and store it in a buffer
// Inputs: 1) A pointer to a buffer to store a message
// 2) TRUE - wait for a message
// FALSE - only check if a message is available
// Outputs: TRUE if a message was received
// FALSE if wait is FALSE and no message is available
// Note: Data will be filled in at the pointer as follows:
// FROM_ID DATALENGTH DATA...
int1 rs485_get_message(int* data_ptr, int1 wait)
{
while(wait && (rs485_ni == rs485_no)) {}
if(rs485_ni == rs485_no)
return FALSE;
else {
int n;
n = rs485_buffer[(rs485_no+1)%sizeof(rs485_buffer)] + 2;
for(; n>0; --n)
{
*data_ptr = rs485_buffer[rs485_no];
if(++rs485_no >= sizeof(rs485_buffer))
{
rs485_no = 0;
}
++data_ptr;
}
return TRUE;
}
}
#endif
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Jim
Guest
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| Posted: Sat May 27, 2006 11:21 pm |
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Hi,
I tried to highed the code that I added in, but somehow it did not work.
Please look for the variable: "msg_hearder".
Thank |
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