[sebhc] H8-5

Carroll Waddell carrollwaddell at sc.rr.com
Mon May 22 19:06:15 CDT 2006

William Elkins wrote:
> Carroll
> This is a guess!
> On the H8-5 card the clock for the serial uart and the 4800hz clock
> for the modulator were from the same source. Sounds like the PC serial
> port is not in phase with your 4800hz clock. As a test, I think you
> can change the data rate to 300 baud on the H8-5 and you PC and it
> would be more likely to work.
> Bill Elkins
>> But what I want to do is to connect the serial port on my PC to an FSK
>> modulator to create the 1200 Hz and 2400 Hz audio tones that can be 
>> fed into
>> the H8-5 tape input jack. The device should convert the serial data 
>> to audio
>> tones for the H8-5 and they should be identical to the tones  from an 
>> actual
>> tape.
>> I built up an FSK modulator that is just like the one on the H8-5 
>> board. I
>> feed a 4800 Hz square wave to 2 J-K flip flops (74LS131 I think). At any
>> rate I am using the same circuit that Heath put on the H8-5 card. I am
>> watching the audio on my scope, and it looks identical to the wave 
>> shown on
>> the Heath waveform drawings.
>> Only 1 time in my trials did it even start to load. The rest of the 
>> time it
>> does nothing.
> -- 
> Delivered by the SEBHC Mailing List
At this point, all I'm trying to do is make the H8-5 think something 
else is a cassette player.
I'm trying to feed the H8-5 AUDIO INPUT with tones just like the sound 
coming from a cassette player.
The audio from an actual cassette is not sync'd to anything. The PLL on 
the H8-5 creates the clock from the audio coming from the cassette player.
I haven't started to try to create the WRITE half of the project yet. 
I'm still just trying to make the H8 think I have an actual cassette 
player with a tape to load in it.
Delivered by the SEBHC Mailing List

More information about the Sebhc mailing list