1K resistors on TX/RX between FTDI and AVR, what for ?

Using Arduino General Electronics
1

Hello,

Could someone explain me why there are 1K resistors on serial lines between AVR and FTDI chip ?

Would the reason have to do with "TTL level", "CMOS level", "RS232 level" ?

Would that mean that to connect a

Regards,

G.

2

It is to allow you to use pin 0 and pin 1 without the FTDI chip over riding the signal level you put in.

3

It is to allow you to use pin 0 and pin 1 without the FTDI chip over riding the signal level you put in.

If I understand your answer, it means that my AVR will be able to use its serial port on the PINs without being disturbed by the powered-on FTDI chip, correct ?

If correct, won't the 1K resistors "lower" the signal between AVR and FTDI when "talking together" ?

Regards,

4

without being disturbed by the powered-on FTDI chip

Yes, well it allows your signals to over ride them.

won't the 1K resistors "lower" the signal between AVR and FTDI

A series resistor by itself does not lower a signal, for that you need a potential divider.
So 1K as the top of a potential divider with the input impedance of an arduino pin as the bottom leg changes the signal lever only a very little, it's no worth bothering about.

5

Many thans for your answer!

Regards,

G.