Message Edited by jarin on 2008-07-17 10:51 AM
Added p/n to subject.
Ten years later and this became a problem for me while having a need to hack a 68HC908AB32 micro.
Even though this thread is long dead, my post might help someone else who ends up here.
I tried Jaromir's idea of extending the 'Break' length, but it didn't help at all. I used an Atmel micro bit banged in ASM.
I'm convinced that break length is not the problem at all. I tried varying it from the standard 11 bits up to milliseconds in length.
Good news though, I did find the solution ! After writing the Atmel code and wiring up the hardware and wasting shitloads of time, as you do when you're obsessed, I then discovered that all I needed to do was change the algorithm I was using. to the high speed '908_AB32_HighSpeed.08P' rather than the regular 908_AB32.08P. Problem solved !
This worked under both Windows XP SP3 32bit and Windows 7 64bit on two separate machines.
Prolific PL2303TA was the most reliable USB -serial converter. The FTDI FT323R worked OK too, but only if 'Latency Timer' setting was changed from default 16ms to 1ms in both the above operating systems. I had no luck with CP2102 converter.
The only other hardware needed was 2 gates of a 74HC125 IC and 9.1v zener etc arrangement as per the 68HC908AB32 data sheet. So instead of the data sheet's MC145407 in the schematic, the PL2303TA is used instead.
When trying an RS232 com port using a MAX3232 instead of a USB-Serial converter, the high speed algorithm wouldn't work at all. It needed the regular 908_AB32.08P.
Software used by the way was PROG08SZ freebee from PEMicro.
I do have to ask myself: Why did PEMicro never offer this as a solution all those years ago when people were asking them for help ? The answer is clear. They didn't have a f.u.c.k.i.n.g.clue ! Typical low paid help desk employees and not an engineer in sight.
Hope this post helps someone in the future. Cheers Jim