Killing ftdi adapter

Other Hardware General Electronics
1

I’m using an ftdi to usb convertor with a stand alone 328 to program it .
The 328 is powered and the ftdi 5v and Ov are connected too.
The Tx and Rx are only connected to the ftdi . A 0.1uF cap and 10k pull up is used to reset off the DTR line.
I’ve broken a couple of the ftdi devices when programming . They still output 3v3 or 5v , the fault appears to be the rx side has died - no led flash from it when performing a loop back, although the Tx led lights . windows still finds the adapter .

Can’t figure this out , but as a long shot any thoughts ???

2

Is this kind of USB/TTL ?

3

Yes , using the ftdi chipset

4

Look the schematic.

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5

Yep that’s it

6

  • I have use USB to Serial interfaces just like that, never had a problem. :thinking:

  • Please draw a schematic showing the exact connections to the target 328.

BTW

When the target has its own power supply, I always cut the target, FTDI, Vcc pin from the FTDI header.

EDIT

Also, I usually, 90% of the time, add a series resistor to both the target’s TX and RX lines to FTDI header RX TX.

7

I had thought about that - what values did u use ?

The circuit diagram is just Tx to Rx and Rx to Tx . DTR to a 0.1cap, other side to reset with 10k pull-up

8
  • My standard is 240R ( I have 3000 of them :shushing_face: ) but up to 1k should work fine too.
9

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