Hi. I'm working on a project involving a java program and the micro controller NXP P89v664.
The java program which utilises the RXTX package, outputs to the serial port a string of characters to be deciphered by the micro controller.
My java program is completed and outputs correctly as checked by virtual com ports and a c program.
I have written a keil c program to receive the input but I somehow receive random inputs instead.
I used the _getkey() fuction to receive the input and putchar() function to check the output.
I'm new to keil c can anyone shed some light on this pls?
Thanks.
Hi All. Thanks for the replies. I will test the output from an oscilloscope soon. However i do suspect that my formula for calculating the baudrate is at fault.
I lifted this code for initializing the serial port and setting baudrate to 9600
void com_initialize (void) { /*------------------------------------------------ Setup TIMER1 to generate the proper baud rate. ------------------------------------------------*/ com_baudrate (9600);
/*------------------------------------------------ Clear com buffer indexes. ------------------------------------------------*/ EA = 0; /* Disable Interrupts */
t_in = 0; t_out = 0; t_disabled = 1;
r_in = 0; r_out = 0;
/*------------------------------------------------ Setup serial port registers. ------------------------------------------------*/ SM0 = 0; SM1 = 1; /* serial port MODE 1 */ SM2 = 0; REN = 1; /* enable serial receiver */
TI = 0; /* clear transmit interrupt */ RI = 0; /* clear receiver interrupt */
ES0 = 1; /* enable serial interrupts */ PS0 = 0; /* set serial interrupts to low priority */
EA = 1; /* Enable Interrupts */ }
void com_baudrate (unsigned baudrate) { EA = 0; /* Disable Interrupts */
/*------------------------------------------------ Clear transmit interrupt and buffer. ------------------------------------------------*/ TI = 0; /* clear transmit interrupt */ t_in = 0; /* empty transmit buffer */ t_out = 0; t_disabled = 1; /* disable transmitter */
/*------------------------------------------------ Set timer 1 up as a baud rate generator. ------------------------------------------------*/ TR1 = 0; /* stop timer 1 */ ET1 = 0; /* disable timer 1 interrupt */
PCON |= 0x80; /* 0x80=SMOD: set serial baudrate doubler */
TMOD &= ~0xF0; /* clear timer 1 mode bits */ TMOD |= 0x20; /* put timer 1 into MODE 2 */
TH1 = (unsigned char) (256 - (18432000 / (16L * 12L * baudrate))); //18432000=Crystal freq set in the project options
TR1 = 1; /* start timer 1 */
Thanks for the help everyone!
Check it here: http://www.keil.com/c51/baudrate.asp
Then start with a simple "Hello, World" embedded application sending to the serial port, and check that Hyperterminal (or whatever) received the output correctly...
And pay attention to the clearly-stated instructions for posting source code:
www.danlhenry.com/.../keil_code.png
TH1 = (unsigned char) (256 - (18432000 / (16L * 12L * baudrate))); //18432000=Crystal freq set in the project options.
Interesting line. So you want 16 and 12 to be long constants. But does 18432000 seem like it fits in a 16-bit int?
Hi. I have checked the value and used the value TH1=0xF6 but the results are the same. I'm receiving funny stuff from the micro controller like before.
I used a simple program to test but the results are the same as my other program.
SEND: 0x01 0x02 0x03 0x04 RECEIVE: 0xFD 0xFB 0xFB 0xF7
Yes, it is funny indeed.
Hi. Can you send me more examples of your output that is generated? Send ... Receive...
this thread is so dead.
Hi everyone. Sorry for the late reply. Have been testing with different crystals and baudrate.
Microcontroller: NXP P89v664 Flash Program: Flash Magic
Crystal: 14.74756 Baud: 38400 TH1: 0xFE
Results in hyper terminal:
Input: 0 1 2 3 4 5 6 7 8 9 Output: ðþ ñþ òþ óþ ôþ õþ öþ ÷þ øþ ùþ
Results in another program:
Input(HEX): 01 02 03 04 05 06 07 08 09 10 20 30 40 Output(HEX): E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 E0FE(Sometimes FE) F0FE(Sometimes FE) E0FF(Sometimes FF)
Input(HEX): 81 82 83 84 85 86 87 88 89 90 A0 Output(HEX): E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 E0FE(Sometimes FE)
Input(HEX): D1 D2 D3 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 Output(HEX): F1 F2 F3 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3
Using this code:
/*------------------------------------------------------------------------------ MAIN.C: Interrupt Driver SIO Using printf. Copyright 1995-2002 KEIL Software, Inc. ------------------------------------------------------------------------------*/ #include <reg51.h> #include <stdio.h> #include "sio.h" /*------------------------------------------------------------------------------ _getkey waits until a character is received from the serial port. This may not be the exact desired operation (for example if the buffer is empty, this function hangs waiting for a character to be received). ------------------------------------------------------------------------------*/ char _getkey (void) { int k; do { k = com_getchar (); } while (k == -1); return ((unsigned char) k); } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ char putchar (char c) { volatile unsigned int i; while (com_putchar (c) != 0) { for (i=0; i<1000; i++) { /*** DO NOTHING ***/ } } return (c); } /*------------------------------------------------------------------------------ Note that the two function above, _getkey and putchar, replace the library functions of the same name. These functions use the interrupt-driven serial I/O routines in SIO.C. ------------------------------------------------------------------------------*/ code char message [] = "This is a test to see if the interrupt driven serial I/O routines really work."; void main (void) { com_initialize (); /* initialize interrupt driven serial I/O */ com_baudrate (38400); /* setup for 1200 baud */ EA = 1; /* Enable Interrupts */ //printf ("Interrupt-driver Serial I/O Example\r\n\r\n"); while (1) { unsigned char c; //printf ("Press a key.\r\n"); c = _getkey(); putchar(c); // printf ("\r\n"); // printf ("You pressed '%c'.\r\n\r\n", c); } }
/*------------------------------------------------------------------------------ SIO.C: Serial Communication Routines. Copyright 1995-2002 KEIL Software, Inc. ------------------------------------------------------------------------------*/ #include <reg51.h> #include <string.h> #include "sio.h" /*------------------------------------------------------------------------------ Notes: The length of the receive and transmit buffers must be a power of 2. Each buffer has a next_in and a next_out index. If next_in = next_out, the buffer is empty. (next_in - next_out) % buffer_size = the number of characters in the buffer. ------------------------------------------------------------------------------*/ #define TBUF_SIZE 2 /*** Must be one of these powers of 2 (2,4,8,16,32,64,128) ***/ #define RBUF_SIZE 8 /*** Must be one of these powers of 2 (2,4,8,16,32,64,128) ***/ #define TBUF_SPACE idata /*** Memory space where the transmit buffer resides ***/ #define RBUF_SPACE idata /*** Memory space where the receive buffer resides ***/ #define CTRL_SPACE data /*** Memory space for the buffer indexes ***/ /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #if TBUF_SIZE < 2 #error TBUF_SIZE is too small. It must be larger than 1. #elif TBUF_SIZE > 128 #error TBUF_SIZE is too large. It must be smaller than 129. #elif ((TBUF_SIZE & (TBUF_SIZE-1)) != 0) #error TBUF_SIZE must be a power of 2. #endif #if RBUF_SIZE < 2 #error RBUF_SIZE is too small. It must be larger than 1. #elif RBUF_SIZE > 128 #error RBUF_SIZE is too large. It must be smaller than 129. #elif ((RBUF_SIZE & (RBUF_SIZE-1)) != 0) #error RBUF_SIZE must be a power of 2. #endif /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ static TBUF_SPACE unsigned char tbuf [TBUF_SIZE]; static RBUF_SPACE unsigned char rbuf [RBUF_SIZE]; static CTRL_SPACE unsigned char t_in = 0; static CTRL_SPACE unsigned char t_out = 0; static CTRL_SPACE unsigned char r_in = 0; static CTRL_SPACE unsigned char r_out = 0; static bit ti_restart = 0; /* NZ if TI=1 is required */ /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ static void com_isr (void) interrupt 4 { /*------------------------------------------------ Received data interrupt. ------------------------------------------------*/ if (RI != 0) { RI = 0; if (((r_in - r_out) & ~(RBUF_SIZE-1)) == 0) { rbuf [r_in & (RBUF_SIZE-1)] = SBUF; r_in++; } } /*------------------------------------------------ Transmitted data interrupt. ------------------------------------------------*/ if (TI != 0) { TI = 0; if (t_in != t_out) { SBUF = tbuf [t_out & (TBUF_SIZE-1)]; t_out++; ti_restart = 0; } else { ti_restart = 1; } } } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable void com_initialize (void) { /*------------------------------------------------ Setup TIMER1 to generate the proper baud rate. ------------------------------------------------*/ com_baudrate (1200); /*------------------------------------------------ Clear com buffer indexes. ------------------------------------------------*/ t_in = 0; t_out = 0; r_in = 0; r_out = 0; /*------------------------------------------------ Setup serial port registers. ------------------------------------------------*/ SM0 = 0; SM1 = 1; /* serial port MODE 1 */ SM2 = 0; REN = 1; /* enable serial receiver */ RI = 0; /* clear receiver interrupt */ TI = 0; /* clear transmit interrupt */ ti_restart = 1; ES = 1; /* enable serial interrupts */ PS = 0; /* set serial interrupts to low priority */ } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable void com_baudrate ( unsigned baudrate) { /*------------------------------------------------ Clear transmit interrupt and buffer. ------------------------------------------------*/ TI = 0; /* clear transmit interrupt */ t_in = 0; /* empty transmit buffer */ t_out = 0; /*------------------------------------------------ Set timer 1 up as a baud rate generator. ------------------------------------------------*/ TR1 = 0; /* stop timer 1 */ ET1 = 0; /* disable timer 1 interrupt */ PCON |= 0x80; /* 0x80=SMOD: set serial baudrate doubler */ TMOD &= ~0xF0; /* clear timer 1 mode bits */ TMOD |= 0x20; /* put timer 1 into MODE 2 */ TH1 = 0xFE;//(unsigned char) (256 - (XTAL / (16L * 12L * baudrate))); TR1 = 1; /* start timer 1 */ } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable char com_putchar ( unsigned char c) { /*------------------------------------------------ If the buffer is full, return an error value. ------------------------------------------------*/ if (com_tbuflen () >= TBUF_SIZE) return (-1); /*------------------------------------------------ Add the data to the transmit buffer. If the transmit interrupt is disabled, then enable it. ------------------------------------------------*/ tbuf [t_in & (TBUF_SIZE - 1)] = c; t_in++; if (ti_restart) { ti_restart = 0; TI = 1; /* generate transmit interrupt */ } return (0); } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable int com_getchar (void) { if (com_rbuflen () == 0) return (-1); return (rbuf [(r_out++) & (RBUF_SIZE - 1)]); } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable unsigned char com_rbuflen (void) { return (r_in - r_out); } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/ #pragma disable unsigned char com_tbuflen (void) { return (t_in - t_out); } /*------------------------------------------------------------------------------ ------------------------------------------------------------------------------*/
but what do you see with an oscilloscope?
Hi. I dont think i have done the oscilloscope test correctly. I only get 50Hz at the output.
Anyway I am able to get the correct echo of the characters after i transferred the hex file without pressing the reset button on the microcontroller.
After pressing the reset button, I get the funny characters as shown above.
i have need of this software, so please procede me.
What software?
/*------------------------------------------------ Received data interrupt. ------------------------------------------------*/ if (RI != 0) { RI = 0; if (((r_in - r_out) & ~(RBUF_SIZE-1)) == 0) { rbuf [r_in & (RBUF_SIZE-1)] = SBUF; r_in++; } }
the above looks 'strange' and i think wrong, the 'normal' way is
/*------------------------------------------------ Received data interrupt. ------------------------------------------------*/ if (RI) { RI = 0; rbuf [r_in] = SBUF; r_in++; r_in &= (RBUF_SIZE-1); // works only if RBUF_SIZE is a power of 2 }
Erik
As long as r_in and r_out are integers of size 2^n, and the buffer is of size 2^m where m is smaller than n, you don't need to clip them everytime r_in or r_out are incremented.
That means that (r_in - r_out) == 0 represents an empty buffer. And that (r_in - r_out) != 0 represents a non-empty buffer. And that ((r_in - r_out) & ~(RBUF_SIZE-1)) == 0 represents a non-full buffer. And that ((r_in - r_out) & ~(RBUF_SIZE-1)) != 0 represents a full buffer.
So the code checks if there is room to insert (at least) one more character. Since r_in are incremented without a clip, the insert code must do the clipping instead: rbuf[r_in & (RBUF_SIZE-1)]
The advantage with clipping/masking when indexing the array, instead of when incrementing the indices, is that you can fill the array completely full.
If you do clip r_in and r_out directly when they are incremented, you must never fill the ring buffer 100% full or you get into a situation where r_in == r_out means either full or empty.