Re: [avrdude-dev] avrftdi TPI support

[Joerg Wunsch]

As Hannes Weisbach wrote:

> as of SVN r1156, avrftdi now supports TPI (and I hope I didn't break
> anything else in the process).

Thanks!

> Page read and write operations should speed up these operations
> somewhat, but TPI requires to poll a bit (NVMBSY) after each written
> word, so don't expect too much.

I don't see any real option for paged writes in the memory programming
description of these devices.

> Cabling looks like so (monospace font!):
> SCK------------TPICLK
> MISO---R---+
>            +---TPIDATA
> MOSI---R---+

I think a resistor between MOSI and TPIDATA is enough; MISO is an input
only anyway, so it cannot drive any output against the TPIDATA output.

A cabling like that is also used for other selfmade bitbang TPI
programmers.

> Flashing with RSTDISBL fuse programmed is not (yet)
> supported. Unfortunately Atmel does not give a voltage range for
> HV-programming for ATtiny4/5/9/10 or a current on the HV-rail (Maybe
> Joerg can comment on that?). My current idea is to use a voltage
> doubler (Dickson charge pump) driven from TPICLK to generate 9-ish
> volts and switch those to the /RESET pin, somehow. This works,
> because the ATtiny always have to be flashed from 5V.

Other AVRs require the HV on /RESET to be in the range of 11.5 through
12.5 V.  You have to measure the current consumption, but after all,
this is a MOS input only, so I wouldn't expect it to draw much beyond
of about 1 µA.  I think a chargepump voltage tripler with a 12 V Z
diode to limit the resulting voltage ought to be enough.

If you look into the STK500 schematics, they use a chargepump doubler
starting at VIN (which must be at least 7.5 V on the STK500), followed
by a TL431 stabilizer.
-- 
cheers, Joerg               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)