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UART slow speed

 
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nuclear__



Joined: 24 Jan 2015
Posts: 63

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UART slow speed
PostPosted: Tue Feb 09, 2021 11:43 am     Reply with quote

After making a big program that uses rs232, I found out that something is wrong with rs232. I realised that when i tried to send more bytes than my buffer is. I will try to print only things that matters since its big.

I split my payload into 230 bytes pieces, and i use
dbg_printf("\r\nbuffer1 : %u", tx_buffer_bytes());
between pieces to see how quickly buffer draws. 1 byte every 100ms!

Code:
#include "18F47J53.h"
#use delay(internal=8MHz, clock=48MHz, restart_wdt, USB_FULL, act=USB)
#pin_select U2TX = PIN_D4
#pin_select U2RX = PIN_D5
#define USE_TX_ISR
#use rs232(UART2,baud=57600,RECEIVE_BUFFER=250, TRANSMIT_BUFFER=256,parity=N,bits=8,xmit=PIN_D4,rcv=PIN_D5,stream=GSM,TXISR,ERRORS) //xmit=PIN_D4,rcv=PIN_D5,

void main();
   setup_adc_ports(sAN6|sAN5|sAN4|sAN2);
   setup_adc(ADC_CLOCK_INTERNAL|ADC_TAD_MUL_0);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_256);  // 1 sec
   setup_timer_1(T1_INTERNAL|T1_DIV_BY_8);      //262 ms overflow
   setup_timer_2(T2_DIV_BY_16,61,5);      //1,0 ms overflow, 5 ms interrupt
   setup_timer_3(T3_INTERNAL | T3_DIV_BY_8);
   enable_interrupts(int_timer0);
   enable_interrupts(int_timer1);
   enable_interrupts(int_timer2);
   disable_interrupts(int_timer3);
   enable_interrupts(INT_EXT1);
   enable_interrupts(INT_RDA);
   enable_interrupts(GLOBAL);



I have no problem receiving ( by manually checking kbhit() ). The problem is below.
Code:

dbg_printf("\r\nbuffer0 : %u",tx_buffer_bytes());
do{
      if ((log_send)<(total_logs)) 
      {
         memset(body,0,250);
         read_log(log_send); // it creates body
         fputs(body,GSM);
         log_send++;
         dbg_printf("\r\nbuffer1 : %u",tx_buffer_bytes());
         delay_ms(1000);
         dbg_printf("\r\nbuffer2 : %u",tx_buffer_bytes());
         delay_ms(500);
         dbg_printf("\r\nbuffer3 : %u",tx_buffer_bytes());
         delay_ms(100);
         dbg_printf("\r\nbuffer4 : %u",tx_buffer_bytes());
      }
   }  while (log_que==1);


This is what i get in my usb output:

buffer0 : 1
body part1 ..........
buffer1 : 226
buffer2 : 217
buffer3 : 212
buffer4 : 209
next body part.......
buffer1 : 248
buffer2 : 239
buffer3 : 234
buffer4 : 231
next body part.......
buffer1 : 15
buffer2 : 6
buffer3 : 1
buffer4 : 0

So in this example i lost part 2.

I've read many examples and approaches about uart but what is the problem here?
nuclear__



Joined: 24 Jan 2015
Posts: 63

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PostPosted: Tue Feb 09, 2021 12:54 pm     Reply with quote

Well that was probably bad use of delay,
i wrote this code to replace my delay_ms and now its super fast..

Code:
dbg_printf("\r\nbuffer1 : %u",tx_buffer_bytes());
         do{
            delay_cycles( 200 );
         } while (tx_buffer_bytes()>=5);
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