I have a setup which communicates between PC(windows) and Atmega2560 using UART. On PC side I am using Pyserial. From the PC I am sending a paragraph of text byte-by-byte to Atmega2560. The UART configuration is : 2400 baud rate;8 bit data;1 stop bit; No parity; The pyserial code is as follows:
string = "some sample text"
strobe = serial.Serial('com3',baudrate = 2400)
for x in string:
strobe.write(x)
sleep(0.001)
I used an Oscilloscope to check the UART signal on the RX pin of the MCU, and observed that there was a gap of 15ms between two data frames. My questions are :
- Are the data frames in UART, transmitted successively, i.e. after a stop bit , the start bit of next frame begins?
- If the answer to the above question is yes, then is the data transmission speed same as the baud rate?
- In the data transmission(from PC to MCU), without the 1ms delay, the data is getting corrupted. Why is this happening?How can I transmit successfully without any delay?
Also I am sending data back from MCU to PC. When I probed the TX pin of the MCU using the Oscilloscope, there was negligible delay between data frames. I beleive that this is because I am using interrupts for transmitting on the MCU.
I am adding Atmega2560 Code here:
volatile uint16_t address;
volatile char incoming;
uint8_t in_buffer[2000];
void eeprom_write(uint16_t add,uint8_t val){
while(((EECR)&(0x02)) != 0);//EEPE bit
cli();
EEAR = add;
EEDR = val;
EECR |= 0x04;//EEMPE
EECR |= 0x02;//EEPE
sei();
}
ISR(USART0_RX_vect){
incoming = UDR0;
in_buffer[address]=incoming;
address++;
}
int main(void){
/*initialization of uart*/
address = 0;
incoming = 1;
while(incoming!='#'){}
for(uint16_t i = 0 ;i<address;i++)
eeprom_write(i,in_buffer[i]);
}
The termination of data is indicated by '#'.
