Do you mean decoupling capacitors?
Do you mean decoupling capacitors?
It is deleted.
I intended it this way. Both the DAC audio channels (stereo?) are available at J9. But if somebody wants to use the DAC for something else than audio then he can disconnect the audio connections and use J11. In that case a change of the voltage level does not appear on the speaker.hoglet wrote: ↑Fri Mar 15, 2019 10:38 pm- The order of the J14/J15 and C13/14 should be swapped so the capacitors are directly connected to the DAC. Then the connections to J11 should come from after the capacitor, but before the jumper. Otherwise there is a big DC offset on the audio signals on J11.
Yes, they come from the original Atom diagram. And I just copied and pasted them. I have changed them.hoglet wrote: ↑Fri Mar 15, 2019 10:38 pm- I'm not sure that C5/C13/C14 need to be so large. The capacitor forms a high pass filter to block DC. The impedance it is driving is ~10Kohms. Which gives a cut-off frequency 0.7Hz. It doesn't need to be this low. I would use something like 0.47uF polyester film type. Electrolytic capacitors are best avoided this type of application . (large values like 22uF make more sense when driving an 8R speaker directly - is there where the value came from?)
I don't know where it came from. I think I had looked at the wrong place when I putted it there. In the cassette-in there is a similar capacitor. That might have confused me. In the Atom 2k14 diagram there is no C8 equivalent, so I removed it.
You are welcome.
Is there a way to do this only for the current schema? I don't want to mark pins as unconnected in the symbol because that will give other issues, like nc pins connected (in case of a 74*244)....
Yes, there is.
It just makes it easier to connect the logic analyzer with the usual 15cm fake "Dupont" cables if all the connections are in close proximity to each other. But if these signals are difficult to route, the forget about it. Getting good ground routing with relatively thick traces is far far more important!roland wrote: ↑Mon Mar 18, 2019 10:02 pmRegarding the debugging, Hoglet asked to add a small header with RDY and SYNC, is that really necessary because those signals are already available at the I/O connectors. I don't mind in adding them, but there has to be a good reason. The board is complicated enough
I had a look at the design and it is quite complicated.hoglet wrote: ↑Wed Mar 13, 2019 8:54 amCould you make a small carrier PCB to adapt it to a 32-pin DIP footprint, then socket it?
Edit: There is a design here:
https://www.retrobrewcomputers.org/foru ... &#msg_4823
I don't believe there are any issues with swapping address and/or data lines on fast SRAMs. Use whatever order makes the routing easier.
Be careful with the SOJ footprint that's in KiCad. I used the default one (Package_SO:SOJ-36_10.16x23.49mm_P1.27mm) on my 1MHZ Bus FPGA adapter board. I found yesterday it's not very suitable for hand soldering, because the pads don't extend at all beyond the edge of the device. I was able to solder it, using lots of flux, but it was not as easy as I had expected. Really a custom footprint should have been used here, with longer pads.
That's correct. Just like the Godil this Atom will only have TX and RX, no handshake. I did run out of pins on the FPGA module because of other nice features such as six VGA colour outputs which gives this Atom more colours (although not simultaneously). But if you leave out the ADC then you have a few pins available for hardware handshake at the serial port. It's just a matter of adjusting the FPGA.
Thanks for the warning. I looked at your design which footprint to use, so I have the same one. I will enlarge the pads. I moved the SOJ to the other side of the board because that makes soldering easier if it's ever necessary to replace the RAM. The headers of the FPGA module won't be in the way.hoglet wrote: ↑Sun Mar 24, 2019 1:20 pmBe careful with the SOJ footprint that's in KiCad. I used the default one (Package_SO:SOJ-36_10.16x23.49mm_P1.27mm) on my 1MHZ Bus FPGA adapter board. I found yesterday it's not very suitable for hand soldering, because the pads don't extend at all beyond the edge of the device. I was able to solder it, using lots of flux, but it was not as easy as I had expected. Really a custom footprint should have been used here, with longer pads.
Thanks, that's also a nice project - such as all projects with 6502 processors
Oh that would be nice...
It should be easy in KiCAD to add two new layers, one for ground, the other for 5V/3V3.roland wrote: ↑Sun Apr 07, 2019 8:39 pmThe size of the board is about 367 x 112mm. Most of my boards were made by MakePCB but because their website does not work correctly I ordered my last Yarrb boards at AllPCB.com. They are cheaper but I don't know their quality yet. The Yarrb board have been shipped today.
What would be the best practise if I want to add two layers? Or should I just take a chance and order five boards and we'll see what happens?
Should these power and ground layers be on the outer or inner layers? Are these only for eliminating noise from the environment and not for interference between two tracks?