Re: [avr-chat] Dragon: mega slow at dumping Flash, normal ?

[Joerg Wunsch]

Vincent Trouilliez <address@hidden> wrote:

> I have done a programming test, and with JTAG the
> Dragon can program the target very fast, about 6 times faster than
> using ISP (regardless of programmer type and clock speed).

This is basically known for the AVR Dragon.  If you want really fast
ISP (which only makes sense if your AVR clock speed is high), get an
AVRISPmkII: optimum (i.e., AVR clocked with 16 or even 20 MHz), it's
twice or more as fast as JTAG.

Apart from that, JTAG is pretty fast.  On the plus side, the JTAG
programming speed is completely independent of the target's clock
speed (the target is not even required to have a working clock at
all), as JTAG has its own clock.  (Only when debugging through JTAG,
the JTAG clock must (again) not exceed fCPU/4.)

Even though the ISP implementation that is embedded into the JTAG ICE
and AVR Dragon is basically the same as an AVRISPmkII, for some reason
it cannot reach the ISP speed of the AVRISPmkII.  My guess is this is
due to wrapping the AVRISPmkII protocol within the JTAG ICE mkII
protocol, causing additional overhead.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)