TZXDuino 1.16 In TZXDuino 1.15.3 I added a bug that lowered the volume of some Spectrum TZX files and all ZX80/81 TZX, O, and P files so they didn't work for many people. I fixed this for 1.16. You can download TZXDuino 1.16 from here. TZXDuino 1.17 The MAXDuino team added ORIC TAP playback functionality to their firmware which I have adapted to TZXDuino. I don't have an Oric Atmos to test it on so I have been recording the playback and loading on Oricutron and everything I have tried has worked. Obviously things may be different on a real machine. Team MAXDuino have also added a speed up function for Oric TAP files which I will add to TZXDuino 1.18 but so far I have been unable to get it to work correctly. You can download TZXDuino 1.17 from here. And finally there is the updated instruction manual which now tells you how to access Turbo mode for the Electron, ZX80, and ZX81. It also says for Oric but that has not been implemented yet. You can download the pdf of v1.2 fo
Hope to try this next weekend on my ZX81 (and Spectrum 48k). I modded v1.3 to work on my Arduino Mega with LCD Keypad shield - need to add the amplifier but for now it works with a headphone;)ReplyDelete
Nice. Do you have any photographs? It's always good to see other peoples versions.Delete
I made a short video of the Ardiuno with shield working:ReplyDelete
When I manage to test it with my spectrum I'll take more pics!
That looks great.Delete
The amp will be needed I suspect but I do know that many have tested theirs with the ZX81 and have had good results.
Sure I have a few audio Amp ICs lying around (TL081 LM741 etc) - I will add one with adjustable gain (I have a small pcb somewhere which I used as headphone preamp) - will post my results.Delete
Excellent. Can't wait to see your results.Delete
Hi Duncan, I managed to load all the games I threw at it successfully without an additional amplifier. I just added a 2.2uF decoupling cap - here's my 48K loading a couple of games (with composite output mod):Delete
How did you connect the cap? That could be an interesting way to make things easier for people. I have to try that myself.Delete
The 2.2uF cap is connected in series with the digital output of the Arduino - positive on the Arduino pin which drives the output. I chose a rather small cap as the audio frequency of the output is in the 1-2 KHz range and this will definitely assure the signal. The Arduino Mega (as the Mini and Nano) outputs a 5V max "square" wave which is somewhat integrated by the cap smoothing it off slightly - this is a very high peak to peak amplitude, more than double than a headphone one (2.2V peak to peak on 600 Ohms around 1 milliWatt). The input of the Spectrum is in any case decoupled by a much smaller ceramic 100nF cap in series with a 10K resistor to ALU pin 28 so even connecting it directly should supposedly work though I have not tried it. One important aspect could be line noise or ground loops: if you power the arduino with USB and you don't have a good ground you could be introducing noise. I suggest using a battery powered Arduino (I use any LiPo 2 or 3S I have around) to avoid any ground loop related issues if you are in doubt, at least initially anyhow.ReplyDelete
Interesting. Definitely going to have to give that a try to see if it will work on my Speccies and MSX.ReplyDelete