12 years ago.

One addition:

Obviously all "packets" start with 0xf9. It would be a good idea to check incoming data in serial_interrupt() for this byte to be the first, and reset i on match. Christians Code would work well if the first incoming byte is guaranteed to be 0xf9, otherwise the buffer will never hold a proper packet, the memcmp will never match and i will never be reset, causing buffer to overflow.

Thus:

unsigned char d;
if(serial.readable()){          // check availability
      d = serial.getc()
      if (d == 0xf9) {
             buffer[0] = d;
             i = 1;
      } else {
             buffer[i] = d;   // copy the serial input to buffer
             i++;              // increment buffer value
      }
}

If it is not your only intention to do that job, it might be a good idea to place the memcmp within interrupt, checking when i becomes 7 and always resetting i in that case, so it will never overflow.

12 years ago.

Christian and Rainer

First off than you for helping me here. I'm not a programmer by trade so please forgive my naiveté. With the code you have provided I keep getting an "identifier "i" is not identified" on the compile

The following communicates fine as a start, meaning reads proper data.

1. include "mbed.h"

Serial pc(USBTX, USBRX); Serial uart(p9, p10); Connect TX to RX (p9 to p10) or can also use USB and type back in the number printed out in a terminal window

DigitalOut uart_activity(LED1); DigitalOut led2(LED2); DigitalOut led3(LED3); DigitalOut led4(LED4); assign led function

int main() { uart.baud(2400); while(1) { if(pc.readable()) { uart.putc(pc.getc()); pc_activity = !pc_activity } uart_activity = 0; turn off rx led if(uart.readable()) { pc.putc(uart.getc()); uart_activity = !uart_activity; wait(0.01); Turn on LED 1 when data recieved void Tx_interrupt(); void Rx_interrupt(); void send_line(); void read_line();

Circular buffers for serial TX and RX data - used by interrupt routines const int buffer_size = 255; might need to increase buffer size for high baud rates char tx_buffer[buffer_size]; char rx_buffer[buffer_size];

} } }

What follows is giving me the problems. The data is garbled, like a baud rate error, and I keep getting errors. What am I trying to do? Receive the commands via RS-232 then turn a set of GPIO functions on/off. In the program I was hoping to print the command on Cool Term and illuminate an LED when the functions occur. The GPIOs will be driving relays which in turn power a 3 axis motor system.

1. include "mbed.h"

Serial pc(USBTX, USBRX); Serial uart(p9, p10); Connect TX to RX (p9 to p10) or can also use USB and type back in the number printed out in a terminal window

DigitalOut uart_activity(LED1); DigitalOut led2(LED2); DigitalOut led3(LED3); DigitalOut led4(LED4); assign led function

int main() { uart.baud(2400); while(1) { if(pc.readable()) { uart.putc(pc.getc()); pc_activity = !pc_activity } uart_activity = 0; turn off rx led if(uart.readable()) { pc.putc(uart.getc()); uart_activity = !uart_activity; wait(0.01); Turn on LED 1 when data recieved void Tx_interrupt(); void Rx_interrupt(); void send_line(); void read_line();

Circular buffers for serial TX and RX data - used by interrupt routines const int buffer_size = 255; might need to increase buffer size for high baud rates char tx_buffer[buffer_size]; char rx_buffer[buffer_size];

} } }

Any help would be welcome , thanks Thom