Serial.println / terminal on tiny88

I try use simple programe, and i accept this messege on terminal windows. what can I do?

> Executing task in folder terminal: C:\Users\User\.platformio\penv\Scripts\platformio.exe device monitor <

--- Available filters and text transformations: colorize, debug, default, direct, hexlify, log2file, nocontrol, 
printable, send_on_enter, time
--- More details at

--- Available ports:
--- Enter port index or full name:

the main.cpp is:

#include <Arduino.h>

void setup() {

  // put your setup code here, to run once:



void loop() {

  // put your main code here, to run repeatedly:




the platpromio.ini is:


platform = atmelavr

board = attiny88

framework = arduino

board_build.f_cpu = 16000000L

upload_protocol = micronucleus

monitor_speed = 9600

Per attiny88.json this uses the GitHub - SpenceKonde/ATTinyCore: Arduino core for ATtiny 1634, 828, x313, x4, x41, x5, x61, x7 and x8 core (with variants/tinyX8). So, Serial maps to software-emulated UART serial

So, no new USB device for USB-Serial will show up. The core not is not capable of doing that. You would have to connect an external USB-Serial adapter (e.g. an FTDI or ch340 or cp2102 based) to the AIN0 pin, which is PD6, along with GND, to read the serial output.

Other cores have USB libraries (VUSB, Digispark etc.), but USB-CDC does not work on modern operatings with these ATTiny chips very well (Digispark CDC library doesn't work · Issue #10 · ArminJo/DigistumpArduino · GitHub). Most interestingly, other USB functionalities work, but not serial.

Thank you for your answare!
for connect external USB-Serial adapter, which adepter you suugest?

FT232R and CP2102 based adapters are good, like e.g.