Blocking Serial Monitor

Projects Programming
1

Hi,
for Debugging on an ATtiny84 I want to use SoftwareSerial to print to Serial Monitor. For programming the ATtiny I use an USBasp connected to MISO, MOSI, USCK. To save pins SoftwareSerial also shall use MISO and MOSI. On the ATtiny84 pin numbers are 5=MISO=RX and 6=MOSI=TX.
For testing I wrote the following sketch:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(5, 6);  // RX, TX

uint32_t baudrt;
uint16_t lcnt = 0;
uint8_t val8;
uint16_t val16;
uint32_t val32;

void setup() {
 // put your setup code here, to run once:
 baudrt = 38400;
 mySerial.begin(baudrt);
 mySerial.println();
 mySerial.print("Baudrate=");
 mySerial.println(baudrt);
 char vc = ' ';
 char vstrg[24];
 val16 = 134;
 strcpy(vstrg, "hello world!");
 
//  block 1:
//  while (1) {
//    mySerial.print(val16);
//    mySerial.print(vc);
//    mySerial.println(vstrg);
//  }
 
//  block 2:
 for (int i = 0; i < 3; i++) {
   mySerial.print(val16);
   mySerial.print(vc);
   mySerial.println(vstrg);
 }

//  block 3:
//  lcnt = 0;
//  while (1) {
//    if (lcnt == 0) mySerial.println("jetzt while");
//    lcnt++;
//    mySerial.print(val16);
//    mySerial.print(vc);
//    mySerial.println(vstrg);
//    if (lcnt == 5) break;
//  }
}

void loop() {
 // put your main code here, to run repeatedly:

}

Setup() contains 3 blocks of code. With block 1active (the others are commented out) Serial Monitor shows the outputs of this code. Because the screen fills so rapidly, I cannot see if output of baud rate is on the screen.

With only block 2 or alternatively only block 3 active there is no output at all.

When I close the Serial Monitor and show the outputs with a terminal program, e.g. Tera Term, everything is ok with all blocks.

I cannot understand what happens here. Can somebody explain it to me?

2

Curious, how can you interface the TTL serial signals? Did you connect an FTDI to the pins, or something like that?

3

yes, sorry forgot to mention that the pins 5 and 6 are linked via an FTDI back to the PC.

4

Try putting a delay after calling the begin() method.

5

Thank you, a delay(1) is sufficient.

No! A first test was ok with delay(1). Further trials with up to delay(10) failed.
Now, delay(50) seems to be stable.

1 Like
6

@SupArdu, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project.

7

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