On 10 Mar 2005, at 22:28, Ralph Corderoy wrote:
That's good. (I'd explained to Matt that this was what had been achieved with the E3; the suspension of its booting while its EXP port was being tickled.) Matt, did you achieve this with that exp program out of interest?
I didn't - was just sending ESC codes through some dumb mac terminal program; I'll be trying minicom, then the exp program, over the weekend when I get a mo.
The E2's at 9600 baud. Have you a scope that could monitor the E2's TXD? Lastly, was this using the same wiring as on the site for the E3's EXP port, i.e. TXD on the E2 is tip.
PC pin 2, RXD o----------o TXD o-----v | | Emailer 9-pin pin 3, TXD o----------o RXD o-------^ | | 3.5mm stereo D-type pin 5, GND o----------o GND o---------|__| jack plug
It is indeed at 9600 :) Unfortunately, no scope. Seriously considering picking one up these days... So, yes, the wiring is the same in terms of Tx and Rx pins. I 'confirmed' this by measuring a voltage of 5.17V (the same as Vcc5V) on the 'tx' pin which is consistent to a driven pin sitting at dormant '1' (as serial/RS232 usually does), and the Rx pin was at 4.5ish, consistent with probably being a weakly pulled-up input.
Although with JTAG it should be possible to put a little EXP-port downloader into RAM, run it, that pulls down a bootloader which in turn is happy to run the code in Smart Media card inserted in the side of the E2 which would avoid having to flash during development.
Aye yeah; the tiniest possible loader would be good.
Another possibility (that'll be a bit more convenient than JTAGging it each time) would be - if the /WE pin is wired on the board (which I suspect it is) - to reprogram the PBL rom in-situ after downloading a little JTAG loader. We could patch PBL to accept code over serial... Or if we're going to go this route, just replace it. So many options! ;) (I'm still hoping for some sort of buff. ovf. in PBL so we can keep it unmodified - so much safer, easier, less time consuming (in some ways).)
Cheers,
Matt