How to enable serial Forwarding with Arduino as ISP


This is my setup

PC <=Link1=> Arduino Uno as ISP <=Link2=> Custom Board with Attiny

Link1: Normal USB cable
Link2: consists of:

  • 6 wires following that tutorial. Can successfully program and debug with leds (painful)
  • 2 wires Tx/Rx driven by SoftwareSerial from Attiny, and connected to Uno pins 0/1 in a cross manor

Although the Uno runs as a ISP as intended, I need to extend its functionality to forward the serial link to the Arduino Serial monitor for more productive debugging abilities.

Can anyone give me some directions here?

Once you have programmed the ATTINY you need to change the sketch on the UNO and need to involve such as the SOFTWARESERIAL type libraries.

And change the pins on the UNO to the ones you call in software serial.

That will give you the passthrough you are looking for.

Do you think I can extend the Arduino as ISP sketch? I do not want to replace sketches .. as in debugging, I always upload new edits to the target.

I am sure you could and maybe somebody already did but it is waaaay above my skills.

Maybe a search variation on "arduino as isp" with some extra key words might find something.

This may help…

IMHO it is very useful to have a USB-TTL cable. With it you can connect directly to the Rx and Tx pins on the Attiny


Thanks @ballskrewbob and @Robin2

@Coding Badly, Great find .. that's exactly what I was looking for!

Many thanks guys!

Also if you ground the reset pin on the Arduino, you can use it as a USB/serial converter since the RX/TX pins remain active.

tarekeldeeb: Great find .. that's exactly what I was looking for!

Excellent. This is a good place to post follow up questions if you have some.