Re: [avrdude-dev] attiny10 with ftdi and bitbang

[Darell Tan]

Hi Matt,

Basically the reset line would only go down once, and will not be
released until the programming is done. The 2 other lines are the CLK
and DATA. Since the DATA line is only used by one party at a time, if
the tiny10 tried to transmit while avrdude was transmitting, it would
go into an error state and wait for a break. If you could probe the
lines with a logic analyzer, I'd be happy to take a look.

This problem of yours is quite a puzzle, especially if both tiny10s
responded the same way. If the tiny10 can properly frame the zeroes
and respond with the TPIIR correctly, it sounds like some protocol
error occurred somewhere in between.

Well if you have any further thoughts or do get it to work, I'd like
to hear about it.

--
Regards,
Darell Tan


On Sat, Jun 30, 2012 at 7:23 PM, matthew venn <address@hidden> wrote:
> Dan, thanks for this.
>
>> If it's stuck in that loop, it's basically calling program_enable,
>> which sends CMD_SKEY and expects the NVMEN bit in the TPISR register
>> to be set.
>
>
> Yes what I'm seeing is the program enable section (detailed in that Atmel
> pdf) called 64 times before avrdude gives up.
>
> So am I right in that the tiny10 is responding at some points? It's been
> harder than usual to trace because all the comms happens on 1 wire. I'm
> wondering if I could use some diodes on mosi and miso so I could scope
> before they are merged.
>
> Someone at the hackspace I'm at (Bristol) has an avrisp mk2 which can do
> TPI. So I'll try that. I've had exactly the same thing with another attiny10
> so I think it must be my wiring or the software/pc side of things.
>
> One really odd thing I noticed about avrdude and the dasa config was that
> when I was testing the outputs of the ftdi cable to check that I was getting
> clock etc, was that if I had
>
> reset = 7
> sck = 3
>
> that would work (both lines generated pulses), but with
>
> reset = 3
> sck = 7
>
> only one of them would then generate signals. I've written those from memory
> so I'm not entirely sure which way round they are but it seemed like a bug
> to me at the time and now I'm wondering if there is something similar with
> mosi and miso. Except that the mosi miso link check tests OK...
>
> Oh well, I'll get there in the end I imagine!
> Thanks again,
>
> Matt
>
> --
> Matthew Venn
> mattvenn.net