[HH] arduino help: write protect, USB FTDI, ICSP, all connect to reset

[Greg London]

> Greg London wrote:
>>> ...the designer is using AC coupling. Perhaps that's obvious. When DTR
>>> goes low, it'll briefly pull down the micro's reset pin.
>>
>> The AC coupling I understand.
>
> OK, good. Just to flesh out the rest of the thought to anyone for whom

20 years as a digital engineer...
Most of that time spent on crazy, highly complex cores that
were part of an even larger, crazy complex ASIC/SOC.

This is the first time I've fiddled with an Arduino.
I got a starter kit and ran through a bunch of sketches
and breadboarded some proof of concept things.

It's also the first time that I needed to understand serial.
I've work a lot with 32 or 64 bit wide internal busses that
handle out-of-order pipelined arbitration. Just never got
around to learning serial.

;/


>> I have read some people disconnectiong the USB FTDI DTR/RTS
>> pin from the atmega reset...
>
> Did they say why? Given lots of people are using these FTDI chips with
> the DTR attached this way, there should be plenty of reports of flaky
> behavior, if that's what is happening.


I can't remember. I've been cramming through websites trying
to soak up everything I need to know to put an unprogrammed
atmega into my own design and turn it into something that
can be programmed as if it were an arduino.

It might have been because they had RTS connected to reset
instead of DTR. Maybe? Can't remember for sure.

Connecting DTR to the reset of the atmega chip via a surface
trace that can be cut with exacto knife would be cheap insurance.
If it works, no sweat. If it has a problem, a quick cut should
fix it.

Greg